FUNDAMENTALS OF PACKAGING GRAPHECS ARE} DECORATKON: Fifi DEVELOPMERT OF AN UNEMRAWATE LEVEL CQURSE EN PACKAGING GRAPHICS Than-En go» Hm Dogma of M. S. MICHlGAN STATE UNIVERSITY John R Heudee £9136 MWfi‘J‘TIBCO '35? Mi] ABSTRACT FUNDAMENTALS OF PACKAGING GRAPHICS AND DECORATION: THE DEVELOPMENT OF AN UNDERGRADUATE LEVEL COURSE IN PACKAGING GRAPHICS by John.R. Hendee In response to the need orpressed by the faculty of the Michigan State University School of Packaging for an undergraduate level course in.pcckaging graphics, a survey of the fundamentals of package printing. its marketing inportenoe. printing and platennking tech- niques, and application to packaging materiel: was com» piled. The survey is supplemented with e course out- line. lecture schedule and suggested laboratory exer- ciees. FUNDAMENTALS OF PACKAGING GRAPHICS AND DECORATION! THE DEVELOPMENT OF AN UNDERGRADUATE LEVEL COURSE IN PACKAGING GRAPHICS By John R. Hendee A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Forest Products School of Packaging 1966 PREFACE Since its inception in 1952. the Michigan State University School of Packaging has constantly endeavored to maintain and improve its curriculum offerings to its students. Until a few years ago, the majority of courses offered were oriented toward the general concepts of pack- aging materials, systems, machinery and others of use to the packaging engineer. As the enrollment and faculty increased, new courses designed to educate the student in package deveIOpment and management were established. In addition, it was realized that a complete, undergraduate level course in the area of packaging graphics would be a worthwhile addition to the curriculum. This paper was written to fulfill this need. The course is not intended to be an extensive study of all aSpects of packaging graphics, but is, instead, designed to introduce packaging students to the fundamenp tale of packaging graphics as should be understood by the packaging engineer. Its scape is limited to consumer. or retail. packaging graphics with particular emphasis on the printing methods used for packages and packaging materials. photomechanics and platemaking. and color process print- 11180 11 This paper is designed to be used by the instructor of a packaging graphics course as a guide to lecture and laboratory preparation. It is also hoped that it will be used as a student reference to supplement the text book or books chosen by the instructor of the course. To Dr. H. J.Baphael. Professor, Michigan State University School of Packaging. I am greatly indebted for the continued guidance, encouragement and assistance pro- vided during the preparation of this paper. His advice and suggestions for reference materials and course some tent were valuable contributions. I am also indebted to the many manufacturers and suppliers of packaging materials and graphic arts supplies, too numerous to mention. from whom much information some tained in this paper was gleaned. To my wife Nicki. I also extend my heartfelt gratitude for many months of patience and encouragement. without which this paper would not have been.possible. 111 TABLE OF CONTENTS Page PREFACE O O O O O O O O O O O 0 O O O 0 O O O I O O 11 PART I. INTRODUCTION TO PACKAGING GRAPHICS Chapter I. PACKAGING GRAPHICS DEFINED . . . . . . . . . 2 II. PACKAGING GRAPHICS: A NEW MARKETING ELEMENT 4 Traditional Marketing Disciplines The Evolution of Packaging As A Marketing Tool The Role of Packaging Graphics In The Retail Market PART II. PACKAGE DECORATING PROCESSES III. INTRODUCTION TO PACKAGE PRINTING . . . . . . 13 Packaging Decorating Techniques Package Printing IV. LETTERPRESS PRINTING . . . . . . . . . . . . 16 Invention and Early Developments Description and Operation of Letterpress v. FLEXOGRAPHIC PRINTING . . . . . . . . . . . 23 Modified Letterpress Printing DeveloPment of Flexographic Printing Description and Operation of Flexography VI. OFFSET LITROGBAPHIC PRINTING . . . . . . . . 29 History of Lithography Description and Operation of Offset Lithography VII. ROTOGRAVURE PRINTING . . . . . . . . . . . . 34 History of Rotogravure Rotogravure and Gravure Description and Operation of Rotogravure iv VIII. IX. X. XI. XII. XIII. XIV- XV. XVI. SCREEN PROCESS PRINTING . . . . . . . . . . Screen Process Defined History of Screen Process Screen Process Printing for Packages Screen Process PreSses ELECTROSTATIC PRINTING O O O O O O O O O 0 History and Related DevelOpments Description and Operation of Electro- static Printing HIBRID PRINTING PROCESSES . . . . . . . . . Dry Offset Printing Wrap-around Letterpress Xographio Printing TRANSFER PROCESSES e e e e e e e e e e e Hot Stamping and Roll Leaf Decalcomania Heat Transfer Printing Labeling HYBRID TRANSFER PROCESSES . . . . . . . . Electronic Transfer Decalcomania Multi-colcr Heat Transfer Inpthe-mold Heat Transfer COATING OR INPREGNATING PROCESSES . . . . . Painting Dyeing PART III. ORIGINAL ART AND PLATEMAKING PREPARATION AND CARE OF ORIGINAL COPY . . . Line Cepy Halftone Cepy Color Cepy Care and Handling of Original Cepy INTRODUCTION TO PHOTOMECHANICAL PLATEMAKING PLATEMAKING FOR LETTERPRESS AND FLEXOGRAPHY Line and Halftone Photoengraving Duplicate Plates Flexographic Rubber Printing Plates Plates For Wrap-around Letterpress and Letterset Page 39 #6 52 57 6b 67 7O 77 79 XVII. XVIII. XIX. XXI. XXII. PLATEMAKING FOR OFFSET LITHOGRAPHY . . . . . Surface Plates Deep-etch Plates Multi-metal Plates Step and Repeat Photooomposing PLATEMAKING FOR ROTOGRAVURE . . . . . . . . Conventional Gravure Platemaking Lateral Hard Dot or Half Tone Gravure Platemaking PLATENAKING FOR SCREEN PROCESS . . . . . . . PART IV. COLOR PRINTING COLOR THEORY, MATCHING AND MEASUREMENT Light, Pigment and Color Color Identification Color Matching Color Measurement COLOR PROCESS PLATEMAKING AND PRINTING Original Color Copy Preparation Color Separation Negatives Color Correction Color Halftone Negatives Color Plates Color Printing Presses PRINTING INIXS O O O O O O I O O O O 0 O O 0 Composition of Printing Inks Printing Ink Vehicles Printing Ink Pigments Miscellaneous Printing Ink Elements Printing Ink For Packaging Papers Printing Ink For CelIOphane, Plastics and Metal Letterpress Inks Flexographic Inks Offset Lithographic Inks Rotogravure Inks Screen Process Inks PART V. DECORATING PACKAGES AND PACKAGING MATERIALS XXIII. INTRODUCTION TO DECORATING ON PACKAGE SUBSTRATES . . . e . . . . . . . . . . . vi Page 89 9b 98 10% 113 123 136 Page XXIV. DECORATING PAPERBOARD AND CORRUGATED CONTAINERSOOOeeeeeeeeeeeee 138 Folding Carton Printing Corrugated Container Printing XXV. DECORATING FLEXIBLE PACKAGING MATERIALS . . 14“ Paper Wrap, Bag and Label Printing Cellophane Printing Foil Printing Plastic Film Printing XXVI. DECORATING PLASTIC, GLASS AND METAL CONTAINERS 15o Plastic Container Printing Metal Container Printing Glass Container Printing APPENDIX I. COURSE CONTENT . . . . . . . . . . . . 156 APPENDIX II. SUGGESTED LABORATORY EXERCISES . . . 168 BIBLIOGRAPHYeeeeeeeeeeeeeeeeeee173 vii PART I INTRODUCTION TO PACKAGING GRAPHICS CHAPTER I PACKAGING GRAPHICS DEFINED For a package to eerve ae an effective eelling device for a product in today‘e aarketplace. it aunt be a hand- eoae. attenticnpgetting, interest-holding and convincing ealeenan. The deeign and creation of such a package doee not occur aerely by chance. but is a direct result of an ex- tensive, well-planned and preciecly executed prograa of packaging graphice. The artist muet pool hie recourcee with thcee of the motivational paychclogiet. the ink laker. the printer and the package eupplier alike to aeeure that all of the graphic elenente on the package-othe brand iden- tification. the illuetraticne. internaticn. inetructicne. directionan~are acting as a teaa to provide aaxiaua impact and ealee etfectiveneee at the loveet pceeible coat. The etudy or packaging graphics, then. is the etudy or package decorations why it ie neceeaary, how it ie done. who dcee it and hue it ie evaluated. In chart. the etudy of packaging graphice. or package decoration, includes all proceeeee, aethcde and techniquee. mechanical or ctherviee. directly or indirectly neceeeary to prepare. create and evaluate the surface deeign of a package. It can be easily eeen that a complete work on packaging graphice could easily r111 several voluaee without even touching upon the technical anecte of de- eign. plateaaking. printing or testing. Purtheraore. such a work would be of little use ae no one person.eould be expected to know all there is to know about packaging graphics. Each area of packaging graphice is a highly epecialized field employing creative artiete. skilled tech- nicians and highly trained craftsmen. As such, thie dissertation.ie written an a primer. an RABc'e of packaging graphics. with epecial enphaaie on the aechanical processes used to decorate coneuaer packages. CHAPTER II PACKAGING GRAPHICS: A NEW MARKETING ELEMENT Selling a product on today's retail market is a _.___....__ M ”_._.__,____...— complex. overwhelming. aulti-dimensional task. The factors _.__.———--- _.__.—-_.._._..- contributing to the ultimate success of a product are vir- _,_ ._._, _"h-——-—"“’— -”—~'—'H——m_ ‘ __ ....__ _ tually without number. Failure to recognize any one of the W -‘—__M factors spells disaster to the success of the product, given that competition has done a acre thorough Job of preo senting the product for sale. And this is true not only for a new product. An old, established product also aust be constantly re-evaluated and its marketing strategy changed to meet the dynaaio needs of the market place. d Ma k so aoFortunately. how- over. the multitude of crucial variables involved in sue. cessful marketing have been classified and categorized into a relatively small nuaber of disciplines. within which the marketing nan can center'his activities. The disciplines receiving the greatest amount of attention. although aany tines somewhat nebulous and abstruse, have traditionally been concerned with the develOpment of the product itself. production, transportation and distribution. pricing. adver- tising and promotion. 5 As eaphas is has been constantly placed on the develop- aent, analysis, working and reworking of advanced product research and developaent methods: production aanageaent and scheduling techniques; transportation and distribution acdelsc and pricing and advertising strategies, each dis- cipline has taken its turn at the forefront of aarketing theory and practice. A acre recent analysis of corporate aarketing practices will reveal. however. that packaging, which has traditional- ly been an after-thought. is today in the aarketing spot- light. Progressive and forward-thinking corporation exec- utives are realising for the first tiae in the history of contemporary retail aarketing that packaging is a crucial. all-iaportant factor contributing to the ultimate success of a particular aarketing plan. They have been shown re- peated instances in which even a slight, seemingly insig- nificant change of a package design sent sales figures scar- ing upward to new heights. or plunged them to all-time lows. no as i asaarkei «But why this sudden interest in packaging as a aarketing tool? The increased focus of attention on packaging as a vital link in retail marketing can possibly be best understood through a brief analysis of the gradual change occurring in retailing practice and organization over the years. For purposes of analysis, the house-toohouse sales- cam-descendant of the early traders and wandering peddlers «can be considered the earliest retailer regularly Operating in the United States. His Job consisted. and still does, of selling himself. The quality of the prod- uct and of the packageo-if indeed there was a package--was not nearly,as important as the personality, dynamism and aggressiveness of the salesman. A good sales pitch would usually result in.a sale. Preceeding the Civil War, the general store took on the burden of retailing in this country, as it was almost the only existing type of retail outlet at that time.1 Selling most of their commodities from bulk containers such as the old, familiar cracker and pickle barrels. the qual- ity of the product certainly was a greater factor than it was previously. but packaging as we think of it today still did not exist. Throughout the next several decades, many limited-line retail outlets emerged, specialising inla single or single class of commodity such as dry stuffs. groceries, produce. meat, furniture or apparel. It was not until the late 1800's and early 1900's. however, that large-scale retail- ing, so common to us today. came inmo general acceptance. Mail-order. department and chain stores mushroomed prac- tically overnight. Packaging was beginning to emerge as a functional necessity to protect and contain the various 1E. Jerome McCarthy. Rana erial A roach (Homewood. Illinois: 3 chard D. Irw . Inc.. 9 o P0 357° products marketed. but the lack of a great variety of products and the retention of personal service kept pack- aging in the marketing background. During the past several decades. large-scale super- markets and discount houses entered the retailing scene. These stores, stressing the concept of self-service. and selling a large variety of a greater number of increasingly differentiated.products. have been the major factors cone tributing to the wide-spread growth of packaging in.recent times. In.l956. following an extensive review and analysis of current trends in supermarkets and drug. variety. depart- ment. discount. hardware and apparel stores. it was pro. dicted that by 1966 the self-service retail market in the United States would account for nearly $100 billion in sales.2 Although today we see that Fladager's estimate was somewhat Optimistic. there is no doubt that the practice of self-service is reaching new heights daily. and has become one of the predominant themes of contemporary retail market- ing. In supermarkets alone. which in l96h accounted for nearly ho percent of the total $110 billion retail sales, the square foot selling area per store employee rose from hh6 in 1963 to 5&2 in 196“. a 22 percent increase.3’“ 2Vernon Fladager. e Sel Powc 0 ac (New York: HcGraw-Hill Book Co.. Inc.. I933}. pp. 25-3E. 3"The True Look/1963.“ Supcrflarket Herchggdisigg. Vol. 29. No. 7 (July. 1963). “'The True Look of the Supermarket Industry. l96h.‘ Super 597:5» gegchaggisigg. Vol. 30. No. A» (April. 1965). pp. 9~7 - Occurring concurrently with the rise of self-service is the phenomenon that many modern sheppers use the superb market organisation to plan.meals in lieu of using the traditional shopping list. It has been.estimated recently that nearly 70 percent of all supermarket purchase decis- ions are made by the consumer while actually in the store shopping. The 'average.'or "normal” or “typical“ superb market customer spends less time in the store while choos- ing from a greater number of products than.ever before. She no longer relies heavily on shopping lists. and when she does. the list is usually short and contains only gene eral categories of products.5 As previously mentioned. a greater number and variety of products are being offered to the consumer at the retail level than ever before. Every month. hundreds of new or improved products are being placed on the market. Techno- legical advances in product development. foods research. and food processing; improved handling and distribution techniques; new and improved packaging materials and.methods3 and increased consumer demand for more variety and choice are but a few of the factors involved in this trend. It is a common occurrence in marketing and advertising circles to hear the prediction that as many as 90 percent of all the products to be feund on the market within the next decade or two have not even been developed yet. 5'Supermarket Buying Decisions in the U.S..' g¥e 2th out Consumers Bu i Habits Stu (Wilmington. De aware: E. . DuPont de Nemours and Co.. Inc.. Film Department. 1965). Partially contributing to the vast number of products on the market is another important factorb-product differu entiation. As an increasing number of similar products are placed on the market. pagkagigg~gften;diffegentiatag”one _ggg§uot~frogfigngther. Although there are no generally pub- lished figures available to substantiate this assertion. quickly walking past the cereal. cosmetics or laundry-aids aisle in any supermarket. or listening to any cigarette or new automobile commercial will provide more than sufficient evidence of attempted product differentiation. In view of these recent develOpments in large-scale. self-service merchandising of a great number of differenp tiated products. it becomes quite clear why consumer pack- astns. 1..., packaginsjgnthe_rctai1___mkgt. numbness- increasingly important to the marketing strgtggist. Today. with our advanced technology as a tool. it is a relatively simple matter to develop a new or better product. Taking advantage of advances in distribution and pricing techniques. the product can be made available to the consumer when he (ituk wants it and at the best possible price for the manufacturer féifb and consumer alike. But. ivnmthegjinal mlysjgfl_ggyi ”\g W13133.,_9d:°r£1g£9§g__d1'tr1but1°n when: drab. poorly designed package. Product success in today's marketplace can be possible only if the consumer sees the m ~~~~ 10 package._retainswhgr~intgrest in it. selects it from many other oompgumrogsgtgngzukiseuz-P152931 it“ in“ h” —~—~.— .._..___..__....... --. shepping cart. e Bo e acka Gra h cs The Retai arkct-o The package is often more_important than the product itself. It must perform the function of its predecessor-the door» to-door salesmanpubut with the added burden of having to sell visually. It must be_intricately planned to 8°ll‘ quickly and effectively. and must be able to creatc_rspcg£; sales. It must prgzidg_thg*purchaser‘with product identity. functional and psychological information. and a cgmBlete _____,___\\=__ 4_r7 sales talk in the absence of an onethe-Spot salesman or clerk. The packagewmust be. in the true sense of the some- what overworked. but accurate phrase[gigilggt_§glg§man£' Because of the critical role of the package as a visual selling force. packaging graphics today has become of paramount_importance to the marketing*organization. N _____ Just as the door-tc-door salesman must take extreme care in presenting a well-groomed. well-clothed. healthy appear- ance. so must the package fulfill an important function of (\gocd “9335533233 And. Just as modern packaging has only recently become a maJor factor in.marketing strategy. ap- pearance of the package has only recently become a major function of good packaging. Historically. the primary function of packaging was protective in nature. All that was necessary was to 11 contain and protect the product through distribution from the manufacturer to the seller. Very little, if any, idenp tification was deemed necessary. Later, as products were merchandised in.a more competitive environment, it was recognized that convenience in;a;package was also desirable. The package that sold was one easy to hold, easy to handle, easy to store, easy to open, easy to use, easy to close. easy to reuse and easy to dispose of. The salgsgappeal_of 8 package wagwrecognizedaasua,don nt function of packag- ing only within the past decade or two with the rise of the self-service retail outlet. Although packaging appearance, or packaging graphics, is involved in both functions of convenience utility and sales appeal, it is commonly classified as most importantto the sales appeal of the package. Thus, great emphasis has been placed on the importance of packaging graphics by manufac- turers, suppliers, buyers and sellers alike. As Robert P. Long has so aptly written: Yesterday the printing on.a package served only to label the product; today it iden, tifies, describes, pictures, merchandises, ties the product in with national advertis- ing, and handles the entire selling Job at the point of sale. Today's package, through its graphics, has become an advertising medi- um with the largest circulation ever known.6 6Robert P. Long, Packs e inti (Garden City, New York: Graphic Magazines, Inc.. 9 , p. 11. PART II PACKAGE DECORATING PROCESSES CHAPTER III INTRODUCTION TO PACKAGE PRINTING Package Decorating gechniguesa-Generally speaking:\\ all processes used to decorate packages or packaging mate- rials can be classified into three major divisions: (l)printing, (2)transferring, and (3)coating or impregu”’ mating. Printing, the first major division, involves the application of ink, or an ink substitute, from a printing plate or screen, directly onto the surface of the package or material. Since most paper, paperboard and flexible packaging materials are decorated by printing, most packag- ing decoration is included in this division. In addition, the most well-known.major decorating processes-clatterpress, offset lithography and rotogravure-oare all examples of printing processes. Transfer processes, the second major division, involve application of ink, pigment or other decorating media indir— ectly onto the package or material surface. The decoration is "transferred” to the surface via a material that has been printed prior to the application. Used extensively for "unp printable“ materials such as glass, plastics and ceramics, 13 11+ transfer processes also have limited application on paper and paperboard packages. The third major division of package decorating proces- ses includes coating or impregnating packages for decoration purposes. It is used very little for package decorating, as it is limited primarily for painting, dyeing or otherwise color-coating rigid plastics. Package 2;intigg-In 1&50, Gutenberg first utilized a printing press to make multiple cepies of books, previously reproduced only by hand. Not long after, commercial print~ ing for purposes of package decoration.was formally ini- tiated as paper labels were printed and then glued to glass bottles or similar containers in the 15th century.1 From that time on, printing has been utilized to reproduce hun- dreds, thousands and even.millions of labels and packages, each one identical; exactly the same as the preceding one and exactly the same as all the following ones. ‘Almost all modern printing presses used for package printing today contain the same basic elements. First, an ink or other pigment source, is necessary to make the image upon the material to be printed. Second, a printing plate or screen must be used. The plate contains the image to be printed and serves to transfer the inked image to the print- ing material. Third, an ink distribution system is needed to carry the ink from its source to the printing plate. lLong, OBeOite, p. 1“. 15 Finally, a solid surface is usually necessary to support the material to be printed or to provide pressure between the material and the printing plate or screen. All of these elements, of course, are not included in every type of printing press. Indeed, it is the modifi- cation or absence of one or more of the components which makes one printing process differ from another. For discus- sion purposes in this dissertation, the printing processes have been divided into three functional classifications: (1)printing by pressing ink from a plate onto the printing material, (2)printing by forcing ink through a plate onto the printing material and (3)printing using powdered ink and electrostatic forces to apply the ink. CHAPTER IV LETTERPRESS PRINTING If asked to explain how things were printed, the layman.would typically describe the process known in the graphic arts field as letterpress printing. Of all the major printing processes included in the category of print- ing from a rigid plate.letterpress is probably the most universally known and is, without a doubt, the oldest. Any development dating far back into history is bound to be clouded in dispute, uncertainty and conjecture, and letterpress printing is no exception. Many historians feel that letterpress printing was conceived as early in.histcry as the 5th century A.D. when.'jade, ivory, and metal seals and carved blocks of wood were inked and stamped on paper” by the Chinese and Japanese.1 Others point to the year 712 A.D. as the origin of “relief printing from blocks," and to the date thl A.D. for the development of “movable type characters made from wood and clay" by the Chinese.2 It has also been noted that "the use of separate characters 1David Hymes, Arts (New Icrk: Holt, )3. IbZe 2Long, 22s2$299 P' 23° 16 17 in printing was probably invented by Pi-Cheng, a Chinese. between the years thl and th9,’ using type made of per. celain.3 But whatever the correct names and dates, it can be reasonably assumed that the beginnings of printing using blocks to transfer an inked image to a printing surface, i.e., relief printing, took place somewhere in.the Orient between the 5th and 15th centuries A.D. Iggenpioniand Early Devglgpmentso—Letterpress print- ing as it is known today, however, lay dormant for many centuries until the leO's when.Johann.Gutenberg of Mains, Germany, rediscovered the art of prrnting from movable type. Viewed as the ”Father of Modern Printing” by most graphic arts historians, Gutenberg was the first to envis~ ion the “commercial and cultural possibilities of printing as a process of graphic reproduction,'“ as he printed the first book “impressed from movable metal type and bound with hard covers.'5 This book was the famous Qutenberg giblg. By today's standards, Gutenberg's press was quite crude. It consisted of a modified wine press having a wooden.platen.that screwed down.from above. The hand-cast metal type or wood out illustrations and borders were placed below the platen, the type and blocks were inked, a damp piece of paper or parchment was placed on top of the inked __a_..__ 3 ock (eighth edition; New york: International Paper Company, I96h), p. 8. h m.- 5Elwin E. McCray, ”Graphic Arts For’Journalisms An Introduction? (second edition; East Lansing, Michigan: Hichigan State university Press, 196“), p. 71 (himeographed.) 18 type, and the platen was then screwed down, pressing the paper onto the type. Although slight modifications were gradually made, Gutenberg's press and methods of letterpress printing underwent little change or development for nearly #00 years. Printing as a trade was officially licensed in England in the lh70's and an Englishman, william Caxton, became England's first printer. within a year, Caxton published the first English-language book-«gistogies o; 133;. Follow- ing Caxton's publication, letterpress printing spread rap- idly throughout Europe and was introduced to the American colonies by Stephen Days of Cambridge, Massachusetts, in 1638. Soon.after, Daye, or his son Matthew Daye, published the first book printed in the United Stateso-Tge Whglg _=..ok _-5 ea 'a_ h _.. - 1 neat 1.: a; sh - re, or more commonly known as the g2; gsalm §22§.6 Subsequently, developments in letterpress type-making and presses furthered the commercial popularity and use of this method of printing. In 1620 a Dutchman, William Blasu, developed a method of rolling the type bed.under a stations ary platen to eliminate the need for screwing down.the movable woodenplaten.7 Metal stereotypes, used to make dup~ licate beds of type from an.original hand-set type bed, "were introduced by William God 1:117:25."8 ‘gpie.. p. 1h. 78"... 22.2;t" pe 1h3e 8Lang, loc.ci§. 19 In the early 1800's, the first all-metal relief press was invented in England by the Earl of StanhOpe, followed by the develOpment of steam Operated rotary presses by Frederick Konig in 1800 and 18h6 by Richard Hoe of New York.9 Advances in the past century have been limited pri- marily to deve10pments in improved versatility, platemsking techniques and higher speed presses. Ineline die cutting and creasing methods have been coupled to the presses to ins crease efficiency, and present speeds of up to 1200 feet per minute for web-fed presses and from 1500 to 7500 impressions per hour for sheet-fed presses are easily obtainable.1° Qescgiptiog and 92eratio§ of Lattegpress—oLetterpress, or relief, printing, as the name implies, is a method of printing from raised surfaces, or from a relief. Ink rol~ lers travel over the surface of the printing plate and de- posit thick, viscous ink only on the raised portions of the plate which contains the image to be printed. By pressing the inked plate onto the printing material, or substrate, the ink is transferred from the printing plate to the sub- strate. This process can be repeated time and time again as long as the plate is serviceable. As was pointed out earlier, all printing systems can , be broken down.into separate functional components. Six 9Pocket gal, cp. cit., pp. l7~18. 10"What You Should Know About Package Printing," hode Packs En -clo edia ssue 66 (New York: MoGraw-Hill, Inc.. 19 5 . pp. 55- 5 e 20 components generally are necessary for the basic letter- press system. These are: (l)a supply of ink, usually con» tained in.a receptacle called s fountain or trough, (2)a form or cylinder which holds the (3) metal printing plate containing the raised printing surface, (b)inking rollers to transfer the ink from the fountain to the printing plate, (5)the substrate and (6)a solid surface, either a cylinder or a flat plate, which presses the paper between.it and the printing plate. Although all letterpress systems are, in principle, conceptually identical, various modifications and combinations of the basic ccnponents have led to the development of three major types of letterpress presses- platen, flat-bed cylinder and rotary. The platen press is the oldest and simplest type of letterpress printing equipment in.aperation today. In crude fora, it was the type used by Gutenberg in Geranny in the 15th century and it is still being used extensively today for short runs in.sany small printing establishments. The p1aten.press operates by bringing two flat surfaces to. gathern-the printing plate and the platen, or impression plate-etc make an.impression on the substrate. The ink is transferred from the ink supply via the inking rollers to the raised surfaces of the printing plate. The substrate is placed between the plate and the platen, and an.impres- sion is made when the platen.and plate are pressed together. The substrate is then removed, the plate re-inked, another 21 piece of substrate inserted, and another impression is made. Because of this operating sequence, the platen press can.be utilized only for sheet substrates, and operates at a rela- tively slow pace. The flat—bed cylinder press differs from the platen press in two principal ways. First, instead of utilizing a flat platen to initiate the impression, an.impressicn cylinder is used. Second, the plate is placed in or on.a flat bed, or form, which moves either horizontally or ver- tically under or along the side of the impression cylinder and the inking rollers. The operating cycle of the flat- bed cylinder press follows the following general sequence: (l)the substrate is attached to the inpressicn.cylinder, (2)the bed containing the printing plate moves to one side to be inked, (3)the bed returns, and the cylinder rolls the substrate over the plate, thus making the impression and (b)the substrate is removed as the plate returns to be roe inked. The impression cylinder, therefore, makes two revs. luticns per impressionu-one to print and one to clear the bed and to accept another substrate-othus allowing only sheet-fed Operation to be economical. Press speed is cons siderably greater than.for the platen press. To eliminate the drawbacks of limited versatility and speed inherent in both the platen and the flat-bed cylinder, ’the rotary press was perfected. The single-impression, one- color rotary press consists primarily of two cylinders-can 22 impression cylinder and a plate cylinder. It is similar to the flat-bed press except that the printing plate must be oirved to fit the plate cylinder and only one revolution of the impression cylinder is necessary for each impression. The substrate is fed between the two cylinders and the in» pression is made. An inking roller, located adjacent to the plate cylinder, provides a constant source of ink. CHAPTER V FLEXOGRAPHIC PRINTING godigied Letterpress g;intigg-—Flexogrsphy is thought of by many people in the packaging and printing fields as merely an extension.of letterpress printing. primarily because of the fact that flexography is based on the same general principles of letterpress but uses rubber printing plates instead of metal. Although flexe- graphy is a letterpress system conceptually, there are enough differences between the history and application.or the two processes to warrant separate discussion. En addition. flexegraphy holds a somewhat vested interest in package printing as it “is unique among the printing pro. icesses in.that it was developed primarily for the printing of packaging materials."1 Develgpment o; Elexogggphic gringigg-orhis develOpment took place in.Liverpcol. England. in 1890. The paper bag making firm of Bibby. Baron e Sons, Ltd.. obtained a British patent in.that year for their method of rotary print- ing using rubber printing plates. Although quite a rudi- mentary contraption often referred to as 'Bibby's Folly.” *4 110113, 020 Bate. p0 1190 23 2% this central impression-type press was, never-the-less, a beginning for flexography. or aniline printing. Following several years of development work with inks. rubber plates and presses, in 1905 an English printer, C.A. Holweg, perfected what has been called the first true flexe- graphic press. Patented in 1908. Holweg‘s specific develop- ment was 'a method of printing paper bags . . . on a rotary printing machine which is . . . provided with elastic blocks or type, characterized in that the impression is made with aniline colors dissolved by alcohol.'2 Thus was born the name of the process-aniline printingo-printing with water- soluble basic coal tar dyestuffs ink from rubber plates. For the next two decades, the aniline process under- went little change. either in.aethod. inks or presses. The presses were often hand made and run on.a make-shift basis. This "dealt-yourself” age has been seen by some as a “time many converters not only made their own.presses, but also dyestuffs inks, and usually their rubber plates as well.'3 and printing on.paper bags was the only material utilized in.flexcgraphy. 2Douglas E. Tuttle and O.C. Holland, “Aniline Print- -I,' Modern.Pack , Vol. 23, No. 10 (June, 1950). p. lb . (From Br tish Patent No. 16.519. NOvember 7. 1908). 3Flexographic Technical Association. Inc.. flaggp ra h a nci lee and etices (New Iork: Flexogrephic Technical Association, Inc.. 19 2), p. 3. 25 Some idea of the nature of the aniline printing process at this stage of develcpment is given by Robert Zuckerman in.a paper presented at the 22nd National Pack- aging Forum of the Packaging Institute in.l960: Early equipment was crude, production slow, and press techniques bordered on the verge of witch. craft. The completion of a roll of collaphane was equivalent to a coffee break. The press was stopped, at which time ink and solvent were added to each fountain, all of the plates were thorough- ly scrubbed, surgery not serious enough to stop the press during printing was performed, and as a final gesture before starting the press again, the pressman went through some mysteriousurituals whose significance was known only to him. Just as the aniline process was developed solely for printing on paper bags, it was another flexible packaging material-«cellophanee-which contributed most to aniline printing'e wide spread acceptance and development as a major printing medium. When.cellophane was originally introduced into the United States in the middle 1920's and early 1930‘s, a method of printing was desperately needed. Letterpress and lithcgraphy were unsatisfactory for printing on cells- phane at that time and grayure, although technically feasible, was ruled out as being uneconomical except for long runs. Following developments in.cpaque inks. better presses and more efficient drying systems, the Milwaukee Printing Company (now Hilprint, Inc.) became the first company to print cellsphane by the aniline process in the “Long, OEe OAte. p. 12°e 26 1920's. Coupled with the increased use of cellophane as a flexible packaging material and, in later years, with the rise of new plastic films such as polyethylene and polypropylene, flexography finally became a recognised element of importance in the package printing field. But one obstruction.lay in the path of full accept- ance-onomenclature. Although the coal tar dye aniline inks were rarely used anymore, the name had a harmful connota- tion due to the toxic nature of aniline substances. Thus. many food packagers-prime users of flexible packaging mate- rialso-refused to use film printed by the aniline process. After years of debate and argument on how best to resolve this situation, a drive by the Packaging Institute, and spearheaded by Franklin hoes of the Moestype Corporation. was conducted to coin a new. more appropriate name for aniline printing. Finally. industry members voted on.aev- eral suggested names, and on October 21. 1952, at the Pack- eging Institute's lhth national Packaging Forum. the name flexography was adapted as the "method of rotary letter- press printing which employs flexible rubber*plates and rapid drying fluid inks.'5 Descri t on and oration o exo ra ~~Plexography, then is basically a method of rotary letterpress printing . with slight modifications. As such, the basic design of a flexographio press is quite similar to that of a rotary 5Flexographic Technical Association. Inc.. 22. cit., 1). 2e 2? letterpress press. In its simplest form, the basic flexe- graphic printing unit is made up of three functional sec- tions. consisting of four cylinders or rollers. The first section is the inking section. designed to contain a supply of ink in a fountain. In.addition. the inking section generally contains an inking. or fountain. roll. and a transfer roll. The fountain roll, usually made of rubber. is partially submerged in the ink and transfers ink to the transfer roll. The transfer roll. in.turn. transfers a uniform deposit of ink onto the raised surfaces of an adjacent printing plate. The transfer roll today is usually an Aniloxéroll made of chrome plated etched steel. whereas in the past it was either smooth chrome plated steel or rubber. The Anilox roll is engraved with thousands of tiny cells which contain the ink and provide a regulated amount of ink to be transferred to the printing plate. The inking section may be further improved or sedi- fied with the addition of a doctor blade to level-off the amount of ink on the transfer roll or to clear ink from the nonsengraved portions of the Anilox roll. A doctor blade is also used when only a single, combination fountain- transfer roller is utilized in the inking system. The second section of a basic flexographic printing unit consists primarily of the plate cylinder and the rub- ber printing plate. The engraved rubber relief plate is 6Anilox is a trademark of Interchemical Corporation. N0" York e 28 attached to the plate cylinder which is usually hollow- steel tubing or solid metal. depending upon the desired diameter.7 The method of attaching the plate to the cyl- inder has, in the past, consisted of either gluing or tape ing, but in recent years plates with sticky bookings have been used almost exclusively. Finally, the steel impression roller or cylinder makes up the third sectionp-the impression section. The impression cylinder presses the substrate web between it and the inked rubber printing plate. thus initiating the impression. In summary, the printing unit of a flexographic press operates in the following general sequence: ink from the fountain is transferred to the rubber printing plate on the plate cylinder via a fountain roll and a transfer roll. As the substrate travels past the plate cylinder, the im- pression roll presses it against the plate. thus effecting the impression. 7Tuttle, op. cit., p. 1&8. CHAPTER VI OFFSET LITHOGRAPHIC PRINTING The principle of offset lithography, or planographic, printing is based on the fact that oil and water do not mix. In order to create a lithographic print, the print- ing plate must first be treated in a manner that allows only some areas to retain an affinity for water, and only for oil in other areas. When water is then applied to the plate, followed by an application of an oil-based ink, and then pressed against a substrate, only the inked areas will be transferred to the substrate, thus making a lithographic print. History of Lithographzo-Legend has it that the original water-oil concept of planOgraphio printing was discovered quite by accident by Alois (or Aloys) Senefelder in the late 1790's when, ”. . . with a greasy substance similar to crayon, Senefelder wrote a laundry list on the smooth sur- face of a flat stone. Later when water was spilled over the stone, he noted that the greasy writing repelled the 1 In fact, however, Senefelder, a native born moisture." Austrian working in Munich, Germany, had been develcping a plenographic process of 'chemical printing' for many years A... . ____._ IMOCray, 090 Cite. p. 12s 29 30 as a means of reproducing sheet music. In his book, The Invention of Lithography, Senefelder told how he discovered lithography while searching for a means of etching lime- stone floor slabs as a substitute for etching cOpper plates. Senefelder's invention was considered by most of his contemporaries not as a potential method of commercial printing, but rather as an excellent method of fine art reproduction. And, for the next quarter-century, litho- graphy was used almost exclusively for this purpose. In the late 1820's and 1830's, however, although still basi- cally a method of art reproduction, lithOgraphy found com- mercial application ”in America (as) 'oil portraits' of famous people, and early chromos of the American scene . . . . Textile and tobacco labels in color were widely used; large circus and theatrical posters made lavish use of color."2 Up until this time, lithography was a direct method of printing (i.c., the image was transferred directly from the plate to the substrate) and the plates were drawn either directly on the stone or transferred via gum arabic coated paper. In addition, lithographic presses consisted of crude wooden frames designed to hold the stone and were equipped with a means of rolling the substrate over the inked design. From the 1850's to the early 1900's, however, several developments in each of the above areas led to the .i_____.. 2H. c. Latimer, Surveg o; Lithoggaphx (New York: Lithographic Technical Fo tion, Inc.. 95“), p. 9. 31 growing pepularity of lithography as a commercial printing method. First, in.1850, a steam-driven power press was devel- oped by H. Eugues, a Frenchman, and was made available and used in the United States in 1866. Later, in 1855, another Frenchman, Alphonse Louis Poiteven, deve10ped a method of transferring the printing image from a photographic nega- tive onto the stone by coating the stone with a light- sensitive bichromated albumin.3 In 1889, in an effort to meet the increased demands for speed and versatility necessary for commercial and pack- age printing use, a new type of lithographic printing plate made of thin, photo-sensitive zinc was introduced, and it was immediately adopted for use on.a rotary lithographic press which had been developed at the same time. Production speeds were thus increased and reached as high as 1500 is. pressions per hour.“ But another development in the early 1900's-othe offo set press-was perhaps the most significant advance since the beginnings of lithography. Offset lithography, i.e., transferring the inked plate image to a rubber roller and then to the substrate, was developed to more faithfully re- produce fine dots and tints. The original method was patented in.1875 by Robert Barclay in.England, but was not 3Lons. M” p. 61+. “Ibid. 32 used to any extent in the United States until l90h when Ira c. Rubel of New Jersey built the first American ro- tary offset prees.5 Later develOpments in lithographic inks, web-fed presses and better, more versatile photographic and chem- ical plate-making techniques increased the popularity of offset lithography as an excellent package printing process. It was now capable of obtaining the same press speeds as letterpress, but at substantial reductions in plate costs and preparation time. Descr tion and O erat n of ffse itho ~- Today, especially in the package printing field, the offset, rotary, sheet-fed press is the basic press used for litho- graphic printing. Web-fed rotary offset presses are find- ing great acceptance in the book publishing and newspaper printing industry. However, because of its inability to produce a continuous, repetitive printing image and its ins flexibility in.cut-off length, the web-fed press is not used extensively for package printing at the present time. Research into variable cut-offs is being conducted and may possibly cpen up this method for’packaging use. In addition, there are a few direct (as opposed to offset) lithographic presses in use, both rotary and flat- bed. These presses, however, are not used extensively and are limited to only a few packaging applications, decal printing being the most notable. 5:34., p. 66. .33 The basic elements of the printing unit of a typical sheet-fed rotary offset press differ in two important respects in relation to a sheet-fed rotary letterpress or flexographic press. The inking sections, plate cylinders and transfer cylinders are all identical in concept. How- ever, because of the nature of the oil-water lithographic process and the offset process, a damping section and an offset cylinder must be added to the offset press. Functionally, the damping section precedes the inking section.and has as its function to damp or wet the water- attracting sections (nonpiaage areas) of the offset plate. In this way, no ink will be deposited on these areas when it is applied to the ink-attracting sections (image areas) of the plate in the subsequent inking Operation. After the ink and water have been applied to the planographic printing plate, it comes into contact with the rubber offset, or blanket, cylinder and transfers the inked image to the cylinder. The offset cylinder in turn presses the substrate between it and the machined steel in- pression cylinder, thus effecting the impression. CHAPTER VII ROTOGBAVUBE PRINTING Of the three principal printing processes, gravure, or’acre commonly, rotogravure, is the newest. As has been previously noted, letterpress was developed in the niddle lhOO's and lithography did not gain.reccgnition as a.najor printing process until late in the 1700‘s. In contrast, the principles of gravure printing were not discovered unp til the aiddle 1800's; it was late in that century before rotogravure was developed enough to Justify building presses. And even though gravure was used extensively for newspaper printing throughout the first quarter of the 20th century, it was not until the 1930's that it was accepted on a large scale for commercial or package print- ing. History of gatoggazgge-orhe earliest application of gravure printing, i.e., printing from an.intaglio plate coup sisting of minute cells recessed or engraved below the plate surface, was in 1783 when, “Thomas Bell, a Scotchaan, pro— cured a patent for printing textiles from an intaglic enp graved cylinder . . . by scratching a design into a wax 3n 35 coating . . . and etching out the scratched area.'1 But, as the gravure plates used by Bell were prepared.mechani- cally and not photographically, his process was not true photogravure, gravure's original naae. J. Nicephore Niepce was the first to experiment with photcgraphically-prepared intaglio plates for use on.a printing press. In 181% Niepce perfected a scans of plate asking using a light-sensitive bitumenpccated setal plate, exposing an engraving on.it in sunlight, and then.etching away the solvent-softened (nonpexpcsed) inage areas. Sole years later, in 1852, Fox Talbot developed and patented a aeans of producing plates, using a dichrosated.gelatin I coating on a copper or steel plate which hardened the non- image areas following exposure to daylight.2 Karl Klic (Klitsch or Klietsch), however, is consid- ered by cost printing authorities and historians as the 'Father of Modern Botcgravure.‘ In 1879, Klic developed a sethod of etching copper cylinders for a rotary press using a carbon.tissue process develOped nearly 15 years earlier by Joseph Swann.3 Klic's process was widely accepted in Europe at that tine and was sold privately to several interested parties, 1Intaglio Service Corp., “Gravure“ (New Iorks di Russo m Faun. IMO). CMPtCr 2e 23.x. Cartwright and Robert MacKay, so ravure A Survey of Eurcpean and American Methods ( on, Ken. ckys hacKay Publishing Company, Inc.. 1953), p. l. 31bid. 36 including the Austrian Imperial Printing Office in 1881. From 1893 to 1895, ”the process (Klic's) was acquired by the Storey Company in Lancaster, England, for printing oil cloth and calico, and this is considered the beginning of the successful commercial use of rotogravure.'h In the years following, rotogravure develOped rapidly as a printing process and was in great demand by newspaper publishers with high volume, high speed operations. In the early 1900's, it was successfully adapted for use by the gllustrated London News, a prominent British newspaper. Whether rotogravure was first introduced in the United States ". . . Just after the turn of the century when Ernst Edwards. . . obtained the 11.5. right. . .“5, or with the '. . . formation.of the Van.Dyke Co. in New York in 1903. . .«5, or v. . . in 1911+ (when) Oswald R. Schulz and Charles Singer established a plant in New York to ens grave and print rotogravure cylinders. . .“7, is a matter for historians to resolve. The process, never-the-less, did come to the United States sometime after the turn of the century and was used by the New lork Times in l9lh for its Sunday rotogravure supplements. “Long. Ops Cite. p0 91o 51bid., citing J.S. Mertle, "Evolution of Roto- gravure,“ razgge, August, 1956, pp. 26-30. 6Iblds . p. 920 7Robert hacKay, ”The Remarkable Growth of Rotogravure,“ Pa er Film and F011 Converter, December 1956. 37 Rapid advances in ink formulation, color control, etching methods and techniques, and high-speed presses took place in the following several decades, and rotogra- vure became firmly established as one of the major print- ing processes. Boto vure and avure-Up to this point in the discussion, the terms 'gravure' and 'rotogravure' have been.used somewhat interchangeably. Some authorities difo ferentiate between the two by using gravure when speaking of sheet-fed gravure presses and rotogravure when.refer- ring to webcfed or roll-fed presses. Others refer to roto- gravure and gravure interchangeably to mean any gravure, or intaglic, process utilizing an intaglio cylinder in a rotary press, whether sheet-fed or web-fed. The latter definition is used in this discussion. escri on and erat on 0 etc ravu eo-The print- ing unit on,a basic rotogravure press is composed primarily of three separate systems: (l)the inking system, (2)the intaglio printing cylinder and (3)the impression cylinder. The inking system of a rotogravure press, in con, trast to letterpress and flexographic presses, and some off- set presses, dces not utilize inking rollers to distribute the ink on the printing plate. Instead, most gravurs presses utilize an ink pumping system which floods the in- taglio cylinder with fluid ink, thus assuring that all cells are filled with ink. The plate cylinder can be 38 located either within.the ink fountain itself, or in.a secondary ink bath which is separated from the original ink supply. After the ink has been thoroughly applied to the plate, a complex doctor blade system, similar to the type used on the ink transfer rolls cn.scme flexographic presses, is employed to remove all excess ink remaining on the sur- face (nonpprinting area) of the plate. The doctor blade is a central element in the entire press system and must be carefully constructed and maintained. Following the wiping operation of the doctor blade, the substrate is fed between the plate and the impression cylinder and the impression is made under pressure. Be- cause of the extreme pressures (up to 300 pounds per lineal inch) necessary to obtain.sharp impressions by drawing ink from the cells of the plate and onto the substrate, the impression cylinder is generally made from a heavy, steel core and covered with a oneohalf to sevenpeighths inch thickness of rubber. In.additicn, for large, highpspeed presses, a steel backup roller pressing against the impres~ sion cylinder is recommended.8 8Cartwright and HacKay, OEe O;te. pp. 228-229e CHAPTER VIII SCREEN PROCESS PRINTING As has been previously noted, all of the printiu processes thus far discussed, including letterpress, flexe- graphy, offset lithography and rotogravure, belong to one classification of printing-otransferring an image from a rigid, or semi-rigid, inked printing plate by pressing the plate into contact with the substrate to be printed. Screen process printing belongs to the second general cat- egory of printing which involves transferring ink to the substrate by forcing it through a plate, usually called a stencil or screen. Certain portions of the screen are blocked out and the ink is forced through the open portions, thus effecting the image or print. S r an ass nedo-The terms stencilling, silk screen printing, serigraphy, mitcgraphy and screen process printing are used synonymously by most laymen. Stencilling, although technically a screen process since it involves application of ink through open areas of a solid piece of material, is only rarely used for consumer package print- ing, and is included for discussion only as a background for screen process printing. 39 #0 Screen process printing, on the other hand, is used to a greater, but still limited, extent for package print- ing or decorating. Screen process printing involves block- ing out nonpimage areas of a screen, thus leaving the image areas open so that ink can be forced through the screen.and onto the substrate. serigraphy is the name given to silk screen.printing by Carl Zigrosser, Curator of Prints of the Philadelphia huseum.of Art,1 in 1938 as a result of a NRA project headed by Anthony Veloris. The project was initiated to develop silk screen.printing as a fine art medium and to redeem it "from the purely commercial fate which had over-come it."2 Today, serigraphy is still used to describe the silk screen.process when.used for producing fine art prints. Hitcgraphy, synonymous with screen.process printing, was coined in l9h5 by Albert Kosloff (a leading teacher and author on.aoreen process printing and techniques) in an effort to reduce the confusion caused by the term screen process, usually referring to commercial silk screen print- ing. The definition of screen.process printing as used in this dissertation is taken from Kosloff's defunition.of: mitography: 1Francis Carr, A Guide To Screen.gggcess gfigting, ed. Brian.lnnes and Beatr ce Na s New York: P tman.Pub- lishing Corporation, 1962), p. Bl. 2J.I. Biegeleisen and Max Arthur Cohn, Si k Sore echni use (New York: Dover Publications Inc.. 95 , pp- ~13- #1 The art or processes employed in the produce tion of any printed matter applied with a squeegee device onto any surface of varied materials through a printing plate consist. ing of a fabric or fiber mesh screen that is partly or completely masked, blocked out, or impregnated.3 H s c c Scree cess-Screen.process printing in the form of stencilling is probably the oldest method of decorating known to man, but the screen.prcoess in use today has been extensively developed and refined only withe in the last half-century. Perhaps the first crude stencils were used in.pre-historic caves when the cave-dwellers created hand stencils by "blowing very finely ground col- oured earths . ... around actual hands."“ It has also been recorded that the first use of true stencils took place in the Fiji Islands where the primitive “islanders made stenp oils by cutting perforations in banana leaves and then.ap- plying vegetable dyes through these openings onto bark cloth.'5 As paper was invented and better stencil materials were developed, commercial stencil printing was used widely until the end of the 19th century. Evidence exists to establish the use of stencils for printing a wide variety of items ranging from Buddah images in the Tunpfiuang caves in.China: ceremonial dresses in.Japan, playing cards and 3Albert Kosloff, to re T e A and Cra So so ocess t M waukes: e Bruce Pu is Company. 9 s P. “Carr, OEe 2;Ee, p. 13c SBiegeleisen.and Cohn, Q2: cit., p. 7. “2 broadsheets in France and Germany in the lhth century: wallpaper and book illustrations in England throughout the 1500's; and for prints on furniture, wallpaper, books, posters and textiles in.the 1800's.6 As previously mentioned, however, silk screen printing, or screen printing as it is commercially known today, did not deve10p until late in the 1800's or early in the 1900's. The use of a silk screen.with portions blocked out to replace the cut-out type of stencil was first introduced and patented by Samuel Simon.of Manchester, 7 From l9llb-l918, John Pilsworth, an Amer- England, in 190?. loan from San Francisco, perfected a method of multi- color silk screen.printing by consecutively blocking out areas on the screen that had been.printed previously with a different color. Wide-Spread acceptance of this method of printing (pepularly called Selectasine) was observed, and it cpened the way to further developments in.acreen printing. Some graphic arts historians feel that Pilsworth's development wasso monumental "that the name John Pilsworth is to screen process what Edison is to electricity”8 Following the First World War, developments in screen process printing were rapid and many. Screen.process 6Carr. 22. ogtlg pp. 11-1". 7110108. QEe Bite. 1). 1155. 8Carr, cp. cit., p. 15, citing H. Ashforth Down, “The Origin of Screen.Process,' Display, Design.and Presentatigg, October, 1951. 43 printing machines were develOped, carbonatissue screens were utilized, screen.process supply houses were estabe lished and many experiments and writings cn.the methods and techniques of screen.prccess printing were published.9 From that period to the present day, commercial screen printing has undergone great change, including "sophisd ticated methods of making stencils by photo-mechanical means, halftone printing . . e (and) better and faster mechanized presses."lo For large volume commercial print- ing, such as package printing, the most important recent develOpments have been faster and more versatile presses and the use of stainless steel or nylon screens to replace the easily worn or damaged silk screens. So can ocess t 0 ac es-Soreen.process printing can be used for practically any shape of package or type of packaging material, from flat pieces of paper or paperboard, to square, rectangular, oval, round or tapered glass or plastic bottles or Jars, to large metal drums or cans. Because of this extreme versatility of matea rials and shapes, silk screen presses for package printing are made in.a wide variety of shapes, sizes and speed ca- paoities. 9Kcsloff, cp. cit., p. 3. 10140118. OEe Ollie, p. lll'ée hh Screen Process Pressesy-The printing units of all screen presses, however, contain the same basic elements: (l)a supply of ink, (2)a stencil or screen, (3)a synthetic rubber squeegee to push the ink through the screen, (h)the substrate to be printed and (5)a back-up plate, a Jig, or a vacuum plate or cylinder to hold the substrate in.place. Screen.process can be classified as either manual, semi-automatic or fully automatic. The manual press, which is used only infrequently for package printing, consists of a table upon which is hinged a frame containing the print- ing screen. The substrate is placed in position beneath the screen and the Operator then applies and spreads the ink with the squeegee. Both the frame and the substrate remain stationary as the ink is forced onto the substrate. Screen presses in the semi- or fully automatic classification can be either flat-bed or cylinder. The simplest flat-bed press follows the same operating pro- cedure as the manually Operated machine except that the squeegee movement is mechanized. Also, as with most auto- matic machines, the bed of the press is often coupled with a vacuum pump in order to hold the substrate in position and to assure complete transfer of ink when.printing on.a porous substrate. A variation of the basic flat-bed press described above is a press designed to hold the squeegee stationary while the screen and substrate travel under it. ’45 The cylinder press is similar to the stationary- squeegee flat-bed press with the exception that the sub~ strate is passed under the screen by means of a rotating cylinder, usually vacuumized. Many variations of the cylinder press exist, eSpecially when designed for cylinp drical objects. With.most of these machines, the object to be printed actually takes the place of the rotating cylinder as the object itself is rotated under the screen and squeegee. CHAPTER IX ELECTROSTATIC PRINTING Two of the three major classifications of printing have now been discussedo-pressing ink from a plate as in letterpress, lithography and gravure, and pressing ink through a plate as in screen.procese printing. The third major classification of printing involves pressurelees printing using powdered ink instead of fluid ink, and the utilization of electrostatic forces to transfer the pew- dered ink to the substrate. This type of printing is gene orally referred to as electrostatic printing. Electrostatic printing is one of the newest of all printing and decorating techniques and, by far, the most exotic. Although very little printing has been done com- mercially by electrostatics, limited amounts are being done with the few full scale presses thus far developed. The future of electrostatic printing for package printing looks promising, and since no pressure or direct contact with the substrate is required, application of electro- static printing to print irregularly-shaped packages seems inevitable. History and Related Develogments--In the past few years, several types of so-called electrostatic printing #6 “7 processes have been developed, but as defined in this dissertation, electrostatic printing involves the trans- fer of electrically charged particles of powdered ink (toner) through a charged printing screen.(nct unlike a screen process screen) and onto the printing substrate which is located soae distance froa the screen. Thus, according to this definition, electrostatic printing was not truly developed until early in the 1960's. Historical development of several of the electrostatic principles, however, dates back as far as 1930. In that year, Barbara Scott obtained a 0.8. patent for a process of screen printing using a toner as the ink sodium. The process involved placing a screen.stencil on an electrified surface and rubbing the toner through the image areas of the screen.with a powder puff. Soaetiae later, a Danish patent was issued to Raslussen.who used a charged screen.and sprayed fluid ink droplets, charged by a corona discharge, through the screen which was in contact with the printing substrate.1 In 1937, an.electrostatio process was developed by Chester P. Carlson.and was patented in the United States in l9b2. His process utilized a photoconduotive material, i.e., a material that is nonconductive in.the dark, but 1Samuel B. tharlane, Jr., I'Electrostatic Printing,“ a paper presented at the Fourteenth Technical Conference of the National Printing Ink Research Institute, Lehigh University, Bethlehem, Pennsylvania, September 18, 19 2 (New York: Sun Chemical Corporation, 1962), p. 9. #8 senio or partially-conductive when illuminated, an.iaage stencil screen, a corona discharge and a toner. The photo- conductive plate was charged with the corona discharge, the stencil put in place and then both were exposed to a high- intensity light source which discharged the areas on the plate receiving the light, thus leaving a charged image where the image area of the stencil was. Toner was then applied to the charged image areas which could then be 2 Carlson's invention was fur- transferred to a substrate. ther deveIOped by the Battelle Memorial Institute, and in 19h“ "emerged as Xerography. Xeroprinting was develOped by R. H. Schaffert of Battelle in l9h6, and by 1950 Xerox capiers were introduced."3 About the same time, in l9h8, Goss Printing Press Co., Ltd., and English corporation, was awarded two British pat- ents for a process: wherein ink is transferred from an inked member to the sheet being printed by an electric field of force . . . in relief, by intaglio or gravure, or by plancgraphic or lithographic methods. k A similar method of printing, using a plate not unlike an offset lithography plate, but using toner instead of fluid 21351., pp. 10-11. 3Long, cp.ci§., p. 192, citing J.J. Bheinfrank and L.E. walkup, ”Current Status of Electrostatic Reproduction Processes," 1961 Proceedings of the Technical Association of the Graphic Arts. ”Daniel Smith, “Electrostatic Printing,” ode acko a i , Vol. 36, No. 5 (January, 1963), pp. 118, $35. “9 ink, was patented in 1951 by 8.3. Shaffer. Shaffer used the same principle as did Carlson by utilizing an electric charge to create the printing image on the plate. Smith discusses Shaffer's process: The surface to be printed is introduced between the charged ink image and a cor- ona discharge of the sign apposite to that of the ink image. The electrostatic field created by the corona causes the particles on the image to transfer to the intervening substrate which is then.separ- ated from the printing member.5 Early in.the 1960's, true electrostatic printing began to be developed fully out of the work performed by Clyde 0. Childress and Louis J. Kabell at the Stanford Research Institute in henlo Park, California, and sponp sored by Jerome Flax of San Francisco. Flax later formed the Electrostatic Printing Corporation of America, one of the first companies engaged in full-time research in.an effort to develOp electrostatic printing, their process being called E.P.C.6 Qesggiption.and Qpeggtiog of Electrostatic Paintigg~o The basic electrostatic printing process, as develOped by American.Can Company and the Electrostatic Printing 5;b;d., p. 118. 61h 1963, the Electrostatic Printing Corporation.sold the rights of their E.P.C. process to American.Can.Company which is conducting extensive research for printing on all types of packages and packaging materials. (From Long, OEeO£te. Do 197). 50 Corporation of America and others,7 generally consists of the following elements: (l)a finely meshed metal screen, capable of conducting an electric charge, which is pre- pared with image and nonpimage areas using any screen.pro~ cess stencil preparation.method, (2)the substrate to be printed, which is placed between, and parallel to, the screen and the (3)conductive backing plate, or ground (which can be up to four inches away from the screen), and (h)toner, or dry, powdered ink. The toner is either brushed, rolled or blown automatically onto the screen where it temporarily remains in the open image areas. With the printing substrate positioned between the plate and the backing plate, D.C. voltage is applied between the backing plate and the screen. The two are now charged with Oppo- site electric forces and the charged toner is drawn toward the Oppositely charged backing plate in.a straight ”elec- trical' trajectory. The toner is intercepted by the sub- strate and the toner image is then fixed by heat, or some type of solvent or vapor process. Variations of this basic process normally involve modification of the conductive backing plate, or ground. 7Harris-Intertype Corp. and the head Corp. are develop- ing a five color electrostatic press for printing military maps directly from microfilm. Sun Chemical Company's Gene eral Printing Ink Division is develOping electrostatic . presses with the Unimark Corp. of America. ("Electrostatic Printing," Pa erboard acka i , Vol. 50, No. 5 (May, 1955): PP. 25:53,. 51 McFarlane envisions a rotary electrostatic press on which two screen cylinders are mounted on either side of the sub- strate. Each cylinder acts as the backing plate for the other and the image is produced on both sides of the sub~ strate simultaneously. Another backing plate modification which holds the greatest promise for the future of package printing ins volves electrically charging the substrate itself, which in turn acts as the backing plate for the screen. Both apples and lumber have been successfully electrostatically printed using this concept commercially. 901° 8McFarlane, 02. git., pp. 5-6. 9"Electrostatic Printing In Use," odern ac i , Vol. 36, No. 11 (July,l963), p. 103. m"Electrostatic Bows In,” Modern Packaging, Vol. 38, No. 1 (September, 196“), p. 255. CHAPTER X HYBRID PRINTING PROCESSES As the various printing processes thus far discussed began to be used in ever-increasing proportions as package decorating media, it was observed that the traditional pro- cesses could be improved upon. By modifying the processes in.ane way or another with the purpose of increasing speed or improving efficiency or accuracy, several new types of printing processes have been developed in.reeent years. In particular, the processes now being used for package decorating, or those that show the greatest amount of prom- ise for use, are dry offset printing, wrap-around letter- press printing and Xographic, or threeedimensional print- ing. p2;z;g£§gg§_ggin§iggyoPrinting consistency has been defined as, “the maintenance of uniform print results throughout the run . . . , primarily with respect to color,"1 and has been.a weakness or trouble spot for offset litho- graphy for many years. In an.attempt to improve the con» sistenoy of color offset printing, dry offset printing was 1Charles Hartman, "A Comparison of Wrap-Around Letter- press and Letterset (Dry Offset) Printing For Folding Car» 9 5 : P'310 tons,” gapgrboagg :gckggigg, Vol. 50, No. 5 (May, 1 52 53 developed in 1919. Dry offset (or letterset, transfer printing or indirect rotary printing) has been used com- mercially for many years to print cigarette and alcoholic beverage tax stamps and savings bonds,2 but only recently has it been considered for use in the package decorating field. The dry offset process is a functional modification of the traditional offset lithography, or wet offset, method, as its name implies. As in offset, the dry offset press" transfers on.inked image from a.printing plate onto a rub- ber transfer blanket, and onto the printing substrate. The plate used for dry offset, however, is a relief plate made of thin metal or flexible photopolymer material, as opposed to the planographic metal plates used for wet offset. Ink is transferred directly to the raised image portions of the dry offset plate, offset onto the rubber blanket, and then transferred onto the substrate. No chemical action is neces- sary as is with traditional offset water-oil systems. Dry offset requires no modification.of standard offset presses other than.'undercutting the plate cylinder to accommodate the thicker relief plate . . . (and) the damping system is disregarded.'3 Wra oaro e to ess--A newer development which is actually a modification of letterpress, but utilises the 211314., pa 32s 31.0118. 22a 3;.20. pa 81h 51} plate techniques of dry offset, is wraparound letterpress. . The curved printing plates used for conventional rotary letterpress are bulky, relatively expensive and generally quite time-consuming to prepare. ,_ To overcome these dif- Q fioulties, light-weight, thin, curved photopolymer, sine or magnesium relief plates, similar to dry offset plates, . were developed for use on letterpress presses. . Thus. wrap-around letterpress was born. Using a rotary press, the thin, flexible plate is wrapped-around the printing cylinder, is inked, and prints on the substrate in pre- eisely the same manner as conventional letterpress. Wangraphic printing, or three- ‘ dimensional printing, is in a class of printing by itself. Originally called parallex panoramagraphic printing, Xograa phie printim is more than Just a new printing process as it utilises '5. new kind of camera, a speciallyc-engineered press, and the development of a new coating material." The Xographic process was cooperatively developed after 13 years of research by Visual Panographics, Inc. (a subsidiary of Cowles hagasines and Broadcasting, Inc..5 or Cowles Com- munications, Ine.,6 publisher of Lock sagasine), Eastman “ma-e. Po 198s : 5Ted Sanchagrin, “The new Power of Packaging: hanage- ment Takes Control,“ W, Vol. 290, No. 12 (June 11. 1965). De 1“. 6 “Packaging Pacemakers: Eastman Kodak " ggm mg- aging, Vol. 39, so. 7 (men, 1966), p. 120: 55 Chemical Products, Inc. (a subsidiary of Eastman Kodak Company), and by Harris-Intertype Corporation. To produce an.Xograph negative, a specially-designed screen is placed between the subject and the camera, which ”rides on.a fixed shooting track to take many exposures of the subject, from different angles, on the same negative."7 As a result, the picture is broken up into hundreds of tiny vertical, parallel strips. Conventional offset plates are made from the negative, and the picture is printed on.a special offset press. Following the printing, the print is coated with a specially-formulated polyolefin wax, which focuses in on the original vertical strips and serves as a viewing screen. Thus, a three-dimensional effect is created. Xographic printing was introduced in l96h as "a snail tip-on . . . in the February 25th issue of Lock Magazine and was claimed to be ‘the first three-diaensicnal printing ever achieved on.autonated equipment in.aulti-aillion.press runs for viewing without special glasses'“8 Since then, Xegraphy has been utilized for advertising inserts, for direct nail advertising, in annual reports, for greeting 9 cards and on several magazine covers. Although, at this time, Xcgraphy has not been.used for package decoration, 7gbid. 8 zbid. 9Sanchagrin, loo. cit. 56 all indications point to its use for that purpose, and it should provide the package designer with fresh opportun- ities for visual selling. CHAPTER XI TRANSFER PROCESSES The second aajcr division of package decorating involves transferring a ready-aade design to a package or packaging material. In contrast to printing, which involves applying ink or pigaent to the substrate via a printing plate, transfer processes generally involve transferring or applying a printed iaage which has been pro-printed on another substrate. There are four general categories of transfer process printing or decorating: (l)hot stamping or hot roll leaf stamping, (2)decalcc- mania, (3)heat transfer printing and (b)labeling. Hot Stamping and Roll Leaf-onot stamping noble aetals is one of the oldest methods of decorating, but has only recently been used as a package decorating techndque. Early in.history it was connon.practice to haaaer pure gold or other natal into extremely thin sheets to be used for decorating. The gold leaf, as it was called, was then.placed over the surface to be decorated and stamped with a hot die which contained the image to be decorated. Only that part of the gold leaf which was stamped onto the surface remained. The excess leaf was re-haaaered and used again. Other'aetals such as bronze and silver were also used in.this aanner. 5? 58 This method of decorating was used primarily for books and paper decoratiu and was not changed significantly until the 1920's. Daring this period of time, a method of backing pure gold leaf or bronse foil with a paper, glassine, cello. phane or acetate carrier strip was developed. The foil was coated with a thermoplastic resin which served as an add hesive between the staaped foil and the substrate. Bec- eause of this development, the paper-feil-adhesive laminate soon beans available in web or roll form, thus creating the new process-oroll leaf stamping, or hot roll leaf staap-w ing. Today roll leaves are available in genuine gold: vaso' uum netalised gold, bronse and aluminum; and in nany pig- ment colors} All hot stamping press systas, whether mamal, actor driven, air operated or platen presses, contain the followings (l)the press or table, (”heated stamping dies which press through the (”roll leaf and onto the (”sub- strate which, in turn, is mounted on (5)a supporting fire ture or die. The heated metal die is pressed onto the roll leaf carrier strip made of glassine, cellulose acetate, cellophane er a polyester. Upon melting of the foil or pignent earrier bond, the leaf is released and permanently 1The majority of the historical infomtion on hot roll leaf stamping is based on the panphlet, 'a Guide to Foil Stamping,“ (Hartford, Connecticut: 11. swift e sons, Into. 1965). pro 305- 59 imbedded in the substrate. Depending upon.the type of die used, the substrate stamped, and from which side it is stamped; an inlaid or debossed, raised or inbossed, or smooth effect can be obtained. Decalconania--Decalconania, the second category of transfer process decorating, involves a pro-printed trans- parent film which is mounted on a paper backing and then transferred to the decorating substrate when wetted or moistened. A decal, or wet transfer as it is sometimes called, is usually printed with special plasticised inks on a starch and gum coated cartridge paper. Usually a screen process is used to print decals although theoret- ically any of the major printing processes could be used. The printed decal is then secured to a paper backing sup- port with a water-soluble adhesive. In addition, another adhesive (determined by the surface to which the decal will be applied) is coated on the outer surface of the decal. The decal is usually wetted, thus freeing it fron the paper backing and leaving it ready to be applied. The decal is immediately placed on the decorating substrate and the backing is slipped off. Excess adhesive is washed off from the substrate, and the decal is then.often coated or varnished to improve adherence or skuff resistance.2 2Basic information concerning the decalconania pro- cess was obtained from Carr, op. cit., pp. 106-111. 6O host decalconania is performed by hand today although a few presses are available which will apply decals at a rate of up to #0 per minute.3 . eat as er nti -_-The third major classification of transfer process decorating is heat transfer printing. Heat transfer is basically a combination of the hot stamp- ing and the decalcomania processes. The heat transfer is printed in much the same manner as a decal, but instead of wetting to release the print, heat is used. The transfer is usually gravure printed with special thermoplastic inks on a special heat-release coated paper web. Thus, only a combination of heat and pressure is needed to effect the transfer. The original heat transfer process was discovered and developed by the Dennison Manufacturing Company of Praning- ham, Massachusetts, in 19 55, and is sold under Dennison's trademark, Therimage. It was developed accidentally by . 3.6. Shepherd, a Dennison chemist, who was "trying to devel- op a . . . more efficient heat sealing adhesive to secure rollotype paper labels to cellophane wraps." He noticed that one of the release coatings being used would transfer its entire coating to the cellophane upon the application of heat and pressure. Soon, the process was extensively developed by Dennison and introduced as a commercial decorat- ing process. W _,. 3"What Ion Should Know About Peerage Printing “1.29.3.2”.- a “Heat Transfer Printim " Modern Packaging, Vol. 33 No. l (Septenber 1960), P. 1215: . 61 The equipment and materials necessary to decorate with Therimage consist primarily of: (l)a preheater, (2) the substrate, (3)a heated platen, (h)the Therimage trans- fer and (5)a finishing oven. The substrate is passed through the preheating oven and onto the transferring unit. In.a system designed to apply heat transfers to cylindrical objects, the transfer unit consists of a ro- tating turret, whereas in a system for flat substrates, only a back-up roller or plate is necessary. The Therimage paper web is passed between the substrate and a heated plat- en which applies a given amount of heat and pressure to the web and the substrate. The heat release coating is freed from the web, and both the coating and the printing are transferred to the substrate. The decorated substrate is then passed through a finishing oven which completes the bond, fixes the transfer and imparts a glossy appearance to it.5 ggbeling--The fourth and final classification of transfer process decorating is labeling. Labels, usually paper, but sometimes plastic or metalised plastic or paper, are printed by any of the major printing processes and as such, the discussion of labels and labeling will be limited primarily to the machinery used to apply labels to the sub- strate. S'Deccrating Molded Plastics,“ Modern Plastics Ens - clo edia Issue-~1965 (New York: hoGrmw$HIIII”EEcIT”IVSET¥ W66 . 62 The label material is specially formulated for the substrate upon which it will be used, and is often treated to impart desired characteristics such as scuff resist- ance, gloss and moisture resistance. In addition, an.ad- hesivc is necessary to attach the label to the substrate. Usually a fluid adhesive is applied between the substrate and the label, although water soluble, pressure sensitive and thermoplastic adhesives are often applied directly to the label prior to the labeling process. Again, the type of adhesive used is dictated by the substrate to be labeled. Labeling machinery varies in type from manually operated equipment, which merely applies adhesive to the label which is then.placed on the substrate by hand, to semi-automatic and fully automatic equipment capable of applying labels at speeds of up to #50 per minute. host paper labeling machines operate on,a two-step basis, apply- ing the adhesive, and pressing the label and adhesive onto the substrate. The adhesive can be applied either to the substrate, or more commonly, directly to the label. When done in the latter manner, the label can either be held in position while the adhesive is applied, or the adhesive can be used to transfer the label from a stack of labels to the substrate. When thermoplastic or pressure sensitive ad- hesives are used, no adhesive operation is necessary since the label is pro-coated with adhesive and only pressure and/or heat is necessary to complete the labelnsubstrate bond. 63 After the adhesive and the label have been applied, pressure is usually necessary to fix the substrate- adhesive-label bond. An intermittent motion pressure pad, a continuous notion pressure pad, a moving belt sys- tem with a rolling contact or a continuous brushing arrange- ment may be used for this purpose.6 6Robert J. Geiger and Arthur R. Johnson, ”Labeling Machinery,” nodern Packaging EncyclOEedia Issue. 1266 One cit., pp. 5 O e CHAPTER XII HYBRID TRANSFER PROCESSES Using the general concepts of transfer process decorating, several new innovations in package decorate ing have been develOped within the past few years. These new develOpments, although primarily in the stage of ex- perimentation.and limited use, show great promise for the future of package decorating. Three of the most promising innovations are electronic transfer decalcomania, hot stamped multi-color heat transfers and inethe-mold heat transfers. Electronic Transfer Decalcomania-aA method of trans~ ferring decals through the use of electrical energy instead of water was introduced by Dodge Machine & Tool Company of Hoosiok Falls, New York, at the l96h National Packaging Exposition.1 Although little intonation is available at this time concerning the process and equipment, it is reasonable to assume that greater speeds can be obtained, since no wetting or drying of the decal is necessary. Multi-cclor Heat Transger-oAnother new development currently being experimented with involves hot stamping of 11.0118. 02o BLEe. pp. 169-170e 6h 65 multi-color heat transfers or decals. This process is a combination of the hot stamping and the Therimage pro- cesses previously discussed. A pre-printed transfer is held to a paper web with a heat-release coating. A hot stamp or die, similar to one used in hot roll leaf stamp- ing, transfers the design to the substrate while creating an imbossed or debossed effect following the contours of the design on the substrate. Use of this technique would certainly broaden the application of hot roll leaf stamp- ing since the stamped effect today can usually be only a one color silhouette or letter outline. gppthe-mold Heat Transfer-In-the-mold heat transfers, the new process showing the greatest amount of promise, was orginally deve10ped for use in injection molding, but can be used equally well for blow molding, one of the fastest growing package forming techniques today. This process-- the Kaumacolor Process-owes developed by the Kaumagraphy Company of Wilmington, Delaware, in the 1950's and has been in commercial use for several years. It ”involves a pro-printed design which is incorporated into the surface of a molded plastic bottle, box or other container . . . 2 The pro-printed design, as part of the molding process." called an overlay, is printed by offset lithography and is of the same thermOplastic composition as the container to be made and decorated. The film overlay is usually .003” 2mg. . pe 168. 66 to .005” thick and is "inserted into the mold, held in place . . . and becomes interfacially fused with the mate- rial as it enters the mold."3 The overlay can be inserted either manually or automatically, and is held in place either by gravity, a clamp or with an electrostatic charge. The latter method is suggested and is used most commonly today. It involves "a static charge of approximately 20,000 volts and 100 micro~amps.'u 3Walter L. Hochner, “Molded-In Foils," Modern Plastics Encyclopedia gssue-olg65, op. g;t., p. 761. “Iblde , pa 762a CHAPTER XIII COATING OR IMPBEGNATING PROCESSES The third major functional division of package decorating—ocoating or impregnating processes--finds only limited use for decorating packages, but is mentioned in an attempt to completely cover all facets of package dec- oration. Used primarily for rigid, molded plastic cons tainers, coating and impregnating involves the actual painting, dyeing or otherwise coloring of containers or materials. It must be noted that,although paper and paper- board packages and materials are often dyed or coated, this is generally done for a functional reason and thus, does not fall into the category of packaging decoration. On the other hand, while some functional purpose might be involved, most plastic containers that are colored are done so principally for decoration. Paintigg-Plastic containers, when painted, are almost exclusively spray-painted. Paints used for this purpose consist primarily of some type of solvent-resin system, in which the resin pigment remains on the surface of the printed object after the solvent has evaporated. Both lacquers and enamels are used extensively for painting 67 68 plastics and their use is dependent upon the type of finish wanted, the material decorated and the desired result.1 Most plastic containers deve10p strains as a result of the molding process, often causing the painted sur- face to craze, or crack. Accordingly, most containers are designed to limit strains as much as possible. This, however, is not always possible, and an annealing process, either warm air or warm water passed over the item for a long period of time, must proceed the actual painting process.2 Dyeigg-oAnother process used to color plastic containers is impregnating, or dyeing. Dyeing can be divided into two categoriesooaqueous dyeing and solvent dyeing. Aqueous dyeing, as the name implies, involves the use of‘water as a solvent medium for a coal tar dye. The item to be dyed is immersed in the hot water-dye‘solu- tion, rinsed in hot water to remove any remaining residue, and then dried. Solvent dyeing follows the same general procedure except that an oil soluble dye in.an.aromatic or chlorinated hydrocarbon solvent is used as the dyeing medium instead of water and coal tar dye.3 222m- . p- 7&5. 3"Printing and Decorating of Polyethylene," (Clifton, N.J.: w.R. Grace a Company, Polymer Chemicals Division, 1961). p. he PART III ORIGINAL ART AND PLATEMAKING CHAPTER XIV PREPARATION AND CARE OF ORIGINAL COPY All elements of graphic design on.packages can be classified into three separate types-oline, halftone or continuous tone, and color. More than one type can be re- produced on any given package, and most consumer packages today contain a combination of all three types of graphic design. These are functional classifications as each is prepared in a different manner; each reproduced different- ly for use with a particular printing process; and each is used to obtain unique effects, or to satisfy certain quanp tity and/or cost considerations. All elements of printed package design begin with an original work of art which is subsequently photographed in order to produce a printing plate which will be used to deo- orate the package. This photomechanioal process of making printing plates from original art work is discussed thor- oughly in Chapters xv-XIX. The original subject or art work is called copy, and accordingly, there are three kinds of copy used for package decoration: (l)line copy, (2)half- tone copy and (3)color copy. Line Cgpyr-Line copy has been.defined as “originals in which the design or image is composed of lines or dots, 7o 71 and which can be reproduced in the form of line etchings.“1 Line copy, therefore, includes all cepy containing lines, dots or solid areas having no tonal gradation. In addi- tion, all line copy must be suitable for one color print- ing. Pen and ink drawings, brush drawings, scratchboard sketches, hand printing and lettering, graphs, charts, type proofs and typewriting are all examples of line copy. In general, it can be said that the quality of the final printing or decoration can be only as good as the quality of the original artwork. Accordingly, painstaking effort should be exerted in order to produce as good an.original as possible. Although special drawing papers are frequently employed by artists to obtain special effects on line drawings, Bristol board, a relatively heavy, stiff, white- coated paperboard, is used to the greatest extent. The paper or board used should be as white as possible, but not glossy or coated in a manner so as to cause glare. The ink used should be waterproof and dead-black, free from any bluish tinge or surface reflection.2 All inked lines should be firm and unbroken and when any cross-hatching is done, the line angles should not be 1"The Art of Photoengraving," (American Photcengravers Association, 1952). De 510 2 , This and the following information concerning original line drawings is taken from ”The Art of Photoengraving,“ Tbid., pp. 5-6. 72 less than 30 degrees. If they are, the spaces between the lines will likely be filled with ink during the printing process. For the same reason, the inked lines should not be too close together. Too fine a line is not likely to be reproduced with the desired fidelity on the printing plate itself. To help standardize shading and fine line techniques as an attempt to reduce undesirable overshad- ing and blending, several shading methods have been devel- oped over the years which are pasted, transferred or photo- graphed onto the original. The most well-known of these shading methods or techniques are Bourges shading sheets, Craftint and Benday Process. Since the line proximity and density is so critical, close attention should be paid to the size of the original. It is recommended that the size of the original be twice that of the final print so as to reduce the impact of slight imperfections or defects in the original. This practice will, however, sometimes cause fine lines and delicate shading effects to be lost. When.making type proofs, it is recommended that a nonpglossy, mat surface stock be used and that the impres- sion be as sharp as possible without embossing or causing an indentation in the paper. As with drawings, type proofs should be made with a nonsglossy, good quality black ink, and with type faces that are not too thin or delicate. Typewritten cepy should be done with a clean black ribbon on good quality white paper. 73 In.addition to drawings and type proofs, several methods of cold type composition (as opposed to hand set metal type) and shading have been deve10ped especially for cepy work and are excellent media for photomechanical 3 These methods can be divided into two reproduction. general classificaticns-photographic and monophotographic. PhotOgraphic cold type methods, or photocompcsiticn methods, consist of exposing a negative of a letter or character to a sensitized film or photographic paper. This can be done automatically on.keyboard-type machines or manually, and can produce a Justified line of type on one print or print separate characters which must later be pasted down or photographed into words or lines of copy. Some of the more papular photoccmposition systems are known by the trade names of Fotosetter, Photon, Linofilm, Honcphoto, Alphatype, ATP-Typesetter, Photo Typositor, Headliner, Filmotype, ATP-Hadego, Typro, Foto-Riter, Fotorex, Strip-Printer, Prctype, Optype, Alphagraph and Starlettograph. Nonpphotographic methods of composition.usually take the form of individual letters printed on thin.paperboard or transparent film. The letters are composed and then pasted down on the original, or photographed for the orig- inal. Artype, Craftype and Fototype are well-known.paste- down composition methods. In addition, other methods such An 3Information concerning cold type composition was taken from Hymes, Op. cit., pp. 85-92. 74 as Presstype and Instantype require no pasting down as the characters are transferred from a transparent backing dir- ectly onto copy by pressing or rubbing. Halftone Copy--Almost all other original work not included as line copy or color copy, is considered to be continuous tone, or halftone ccpy. Halftcne copy consists almost exclusively of photographs when used for package decoration, but limited amounts of "sketches, drawings, paintings by different mediums (pencil, crayon, pastel, water color, oil), color prints and color transparencies,"h are also used. As noted with line copy, cleanliness and attention to detail are required of photographs and other halftone copy in order to produce adequate, faithful reproductions for printing plates. It is recommended that a photograph be a "glossy ferrotype print(s) . . . not be unduly flat or lacking in vigor,nor . . . show excessive contrast,"5 and having bluish-black tone in.preference to greenish- black or brown. Halftone originals can be of many varieties, depend- ing upon the desired effect wanted. The basic types of halftones used for package printing are: l. The Square Halftone--Simplest and most econom- ical. Includes any halftone plate with rectanp gular and parallel sides. hAmerican Photcengravers Association, 22. cit., p. 6. sue . 1). 7e 75 2. The Silhouette Halftone-oA halftone plate with all background cut or etched away. Also called an outline halftone. 3. The Highlight Halftoneo-A halftone plate on which the highlight dots or whites of the copy have been etched away so that they will not print. Provides greater black and white contrast. h. The Vignette Halftone-A halftone plate so treated or etched so as to make the edges gradually fade away and blend into pure white space. 5. The Combination Plateo-A.combination.plate is made up of both line and halftone copy, and can consist of any one of the above mentioned types of halftone copy.6 Other halftone plates exist, but are related to color print- ing and are accordingly included in the color printing chap- ter. Colo; Gonzo-Color capy includes all types of line and halftone copy which contain, and will be printed in, two or more colors. Color copy is probably used to a much greater extent than either line or halftone one-color copy for pack- aging, and is thus discussed separately in Chapter XXI (Color Process Platemaking and Printing). Care and ndli o Ori nal Co -~Just as crisp, clean copy will ordinarily result in.a better, more effec- tive and satisfactory printing plate, conscientious care and handling of the original print or photograph will con, tribute much to a better plate. The following suggestions are indicitive of the type of care necessary: 6Hymcs, 020 Cite. ppe 39-h1. 76 1. Avoid using paper clips on prints as the impression left may show up on the plate during the photomechanical platemaking pm0038 e 2. Pencil marks on the back of the print and careless use of a wood-backed rubber stamp should also be avoided for the same reason. 3. Rolling of prints should be avoided if possible since cracks may occur, renders ing the print useless. Prints should be shipped or mailed flat to avoid this. n. Oily overlays such as tracing paper or wax paper might ruin a print if some of the material is transferred to the print. Finger prints also have the same effect. 5. Prints should not be transported face to face as dirt parsicles may damage both during shipment. 7William J. Stevens and John.A. McKinven, gow go NOW e a e and Co 0 Offset tho h (haywo , Jersey: Dorval PuSE¥shing Company, l9gfii, p. 36. CHAPTER XV INTRODUCTION TO PHOTOMECHANICAL PLATEMAKING The next step in the process of package printing, following the preparation of the original artwork or copy, is that of reproducing the copy onto a printing plate or screen, which is then.used to print or decorate the pack- age or packaging material. It has already been seen that package decoration involves not only package printing, but also transfer processes and coating or impregnating pro- cesses. The latter processes, of course, do not require that printing plates be made, as all that is needed is a supply of paint or dye and some method of application. Similarly, no printing plates other than the hot stamp dies are necessary for hot roll leaf stamping. The other transfer processes such as decalcomania, heat transfer, labeling and others, however, require printing plates, not for the direct transfer process, but because the trans- fer must be printed before they are applied. Accordingly, the following chapters (XVII-XIX), are concerned only with the processes necessary to make printing plates for the major printing processes, i.e., letterpress, flexography, offset lithography, rotogravure, and screen process. 77 78 The process by which all printing plates used for package printing are produced is called photomechanical platemaking, or photomechanics. Photomechanics has been defined as "a method of preparation of a printing form by means of photography or photography related techniques, such as the use of light sensitive coating. In general, photomechanics refers to the whole process which begins with photographing the original and ends with completion of the printing form."1 Photomechanical reproduction of the original is basically the same for each printing process. The original is photographed, and the resulting negative is used to ex- pose a plate or screen which has been treated to make it photosensitive, or light sensitive. The exposed plate or screen is then etched, washed, developed, or otherwise treated to differentiate the image areas from the nonpimage areas. The plate or screen is then ready for printing. 1David Pegaz, 'Photomechanics and Printing in.Package Production“ (unpublished academic paper, School of Packaging, Michigan State University, 1965), p. 3. CHAPTER XVI PLATEMAKING FOR LETTERPRESS AND FLEXOGRAPHY Letterpress plates are called photoengravings, and the photomechanical process used to produce photoengravings is called photoengraving. The basic steps in the photo- engraving process are as follows: (l)photographing the original cepy, (2)exposing, or photOprinting, the original negative on a light sensitive plate which hardens the image areas and makes them aoid~resistant, (3)devoloping the plate by washing away the unhardened nonrimage areas, (h)heating the plate to burn in the image, (5)etching away the nonpimage areas to make the image areas stand out in relief, (6)routing out the nonpprinting areas and (7)at- taching the plate to a wood or metal base. Photoengrav- ings can be of three different types-~line, halftone and color-oorresponding to the original type of artwork. Line photoengravings and halftone photoengravings are discussed below, and color photoengravings are discussed in Chapter XXI (Color Process Platemaking and Printing). Line and Halftone PhotcengravingL-As previously mentioned, the first step in making a photoengraving is 1Host of the information concerning photoengraving, unless otherwise indicated, is taken from "The Art of Photo- engraving," op. cit., pp. 12-21. 79 80 the preparation of the original copy. Once this has been preperly done, the original is fastened to a capy board, strongly illuminated with carbon are lamps, focused to the required sharpness and size, and then photographed with a camera using special photographic film or plates. For line copy, the original is photographed as is, whereas with halftone work, the copy is photographed through a halftone screen. The halftone screen consists of two clear glass plates which have opaque lines mechanically ruled diagonals ly from corner to corner. The two plates are placed face to face with the ruled lines crossing at right angles. When the original halftone is photographed through the screen, the continuous tones of the capy are broken down into thousands of small dots, equally spaced, but varying in size, shape and proximity, depending upon the lightness or darkness of the tone. This creates a.mosaic-type pat- tern that, when.printed, gives the illusion.of continuous shades and tones. Halftone plates are ruled in 55 to 150 lines per inch, but only 100, 120, 133 and lSO-line screens are used for plates intended for use with package printing. Screens with fewer lines per inch are generally reserved for printing cn.newspaper or other rough stock. After the negative of the original copy has been developed, it is assembled, or stripped, onto a thick glass plate, called a flat, in reverse. At this time, other negatives to be used for the final printing plate 81 may be stripped to the flat. Each negative must, of course, be of the same relative size as the other. The stripped flat is then placed face down on a sensitized metal plate (usually copper for package printing when a loo-line or more screen is used), in a photOprinting frame. The frame is usually equipped with a vacuum device which insures positive contact between the negatives and the sensitized plate. The negative and plate are then exposed by a powerful arc lamp which hardens the light~sensitive coating on the printing plate where the light passes through. Since the plate is exposed through a negative, the hardened areas are the original image areas, or the areas to be printed. Fol- lowing exposure, the plate is separated from the flat and developed, which causes the nonpexposed, nonphardened coat- ing to be washed away, with the hardened, acidaresistant image areas remaining. The plate is then dried and heated to further fix the image, and is then carefully inspected, with any minor imperfections being touched up by the etcher. The plate is now ready to be chemically etched in an etch- ing machine. Line engravings usually require several etchings, or bites, before the etching process is complete. The first bite is quite mild and is done only to establish a slight relief without loosing the detail of fine lines. The plate is then rinsed, dried and dusted with a fine resinous, syn» thetic powder called Dragon‘s Blood. The powdered plate 82 is then heated, which burns in the powder around the relief characters and makes them acid-resistant, thus preventing undercutting during subsequent bites. The plate is then etched, dried, powdered and heated again. Usually the etch- ing process requires four bites in order to produce a plate with sufficient relief and no undercutting. The etching machine consists of a bath of acid which is Splashed evenly on the plate. A halftone plate may be etched in a similar machine, in a tray containing the acid, or in.an electric etching machine which works on the same principle as electrolysis except that metal is removed rather than added to the plate.2 As in line etching, halftone etching takes place in bites. The first bite of the halftone etching, however, is con- tinued for as long as possible, until the size of the half- tone dots begin to reduce. The plate is then washed, dried and inspected to assure compliance with the original. An acid-resistant ink is then placed on all areas not require ing further etching. This operation is called staging. The entire process is repeated until sufficient clarity and rec lief are obtained. 21h recent years, a oneobite, powderless etching pro- cess called Dow Rapid-Etch has been developed for both line and halftone etching, and is gaining wide-spread acceptance. Special filming agents are included in the acid bath which prevent undercutting without the use of Dragon's Blood. Also, various methods of electronic engraving by the trade names of Scenes-Graver, Klisohograph and Photo-Lathe have been developed recently. These machines produce plastic or metal plates directly from the original copy, thus elimc inating all of the photographic photoengraving steps. Used primarily for newspaper printing, electronic engravers find only limited use for package printing plates today. 83 After the etching process has been completed, the plate is then mechanically routed which removes, or outs to a greater depth, all nonprinting areas, leaving only the lines or halftone dots in high relief. Depending on their use; whether or not the plate contains highlights, middletones or shadows; and the screen size; halftone en, gravings used for package printing are usually etched from .Olh" to .038" deep.3 Line engravings are usually etched to a depth of .030" to .038" deep. The routed plate is then fastened down securely to a wood or metal plate to be used for printing. The final photoengraving and base are then milled or planed down to exactly .918“, the height of regular, cold metal type. Duplicate P1ates--Since the final photoengraving is a flat, relatively thick plate, it rarely is used for letterpress package printing, except on flat-bed cylinder presses when thick carton stock is being printed. Accord- ingly, most printing is performed from duplicate plates, i.e., letterpress printing plates made from photoengrav— ings, type matter, or a combination of both. Generally, duplicate plates are divided into four classifications: (l)electrotypes, (2)stereotypes, (3)plastic plates and (4)rubber plates. Electrotypes and plastic plates are used extensively for letterpress package printing, while stereo- types are used almost exclusively for newSpaper printing. 3”Basic Requirements For Better Electrotypes", (Cleveland, Ohio: International Association of Electrotypers and Stereotypers, Inc., 1957), p. 7. 8b Most rubber plates are used for flexographic printing. In addition, several new develOpments in photosensitive plas- tic original plates for letterpress, wrap-around letter- press and letterset printing have gained wideSpread accept- ance in the package printing industry in the past few years. n are made by using the process of Electrctypes elecrolysis. A thin sheet of lead, plastic, plastic—metal combination, or plastic-wax combination is molded over the original type or photoengraving and faithfully copies the relief plate in every detail. The mold is removed from the original and sprayed with a thin film of silver or graphite. It is then placed in a copper-plating solution and the film of silver or graphite becomes coated with a thin layer of copper through electrolysis. The capper shell is then separated from the mold, placed on a backing material, and planed to the required height. The process of making stereotypes is similar to that of producing electrotypes except that no electrolysis is involved. A matrix or mat consisting of heavy paper or plastic-impregnated paper is pressed or rolled over the type or photoengraving, thus transferring the relief to the mat. The mat is removed, heated until hard and dry, and then placed in a casting box. Molten sterotype metal (usually lead) is poured over the matrix, thus forming “Most of the information concerning electrotypes and stereotypes is taken from "The Electrotype and Stereotype Handbook," (Cleveland, Ohio: International Association of Electrotypers and Stereotypers, Ine.). 85 the sterotype plate, which is then milled or planed to the exact height. Plastic printing plate duplicates are made in exactly the same way as sterotypes except that the ma- trix is usually a resilient elastic material such as rub- ber, and the plate is made from a thermosetting plastic as opposed to lead. The matrix is released and the plate 5 is secured to a backing. Elexographic Rubber grintipg P1ates-Rubber printing plates used for flexographic printing can be made of either natural or synthetic rubber. Synthetic rubber made from coal-tar and petroleum derivatives is by far used most ex- tensively for flexographic plates. Sheets of rubber, usually containing some combination of "accelerating, sta- bilizing, vulcanizing, anti-oxidizing, and plasticizing agents,"6 are molded from a matrix in.auch the same manner as stereotypes and plastic plates. The matrix, usually a phenolic-type thermosetting plastic, is molded over the type or photoengraving under heat and pressure. For certain types of work where extreme detail and accurate register are necessary, special non- shrink matricies containing a thin sheet of perforated metal is laminated between two layers of matrix material. Following removal of the matrix, the layers of rubber plate material are softened over the matrix and then.pressed 5Hymes, op. cit., p. 103. 6FleXOgraphic Technical Association, Op. cit., p. “6. 86 under hydraulic pressure to complete the transfer. The final plate is then trimmed and ground down to the re- quired thickness if necessary.7 The Flexographic Technical Association lists several types of rubber plates commonly used for flexographic pack- age printing today:8 1. Plainbecko-Used for general commercial print- ing where print size and register are not critical. Plate is glued or taped to the printing cylinder. 2. Stickybacko-Dcuble—faced adhesive is bonded to the plate, backed with cloth or plastic. Backing is stripped off and the plate is ad- hered to the cylinder. 3. Pre-curved-oA shrinkage-controlled, laminated plate molded to a permanent curve. Used where accuracy of printing size and register are critical. Mounted without stickyback in the same way as pleinback plates. u. Bress-back-«Plste is permanently vulcanised to a spring brass sheet which is covered with a rubber or rubberized-fabric to prevent creeping on the cylinder. The plate is pre- eurved to fit a specific cylinder size, and is provided with various mechanical methods of securing to the cylinder. Used extensive- ly for printing folding cartons, milk cons tsiners and labels. a es or wra Area to ress and tte s - Printing plates for use on.wrsp-around letterpress and letterset presses have, in the past, consisted of thin zinc or magnesium letterpress plates. In recent years, however, two printing plates have been.developed specifically for zgpig,, pp. b6-u9. BIBLE}! pp. 59-50. 8? this use, and more than anything else, have been a major factor to the growing importance of wrap-around and letter» set in the package printing industry. Both types of plates consist of a metal base and s photochemical, light-sensitive plastic costing which produces a shallow-relief, flexible printing plate. “Dycril“ photopolymer plates are made by DuPont and were commercially introduced in 1960. The basic Dycril plate consists of a flexible metal back upon.which a layer of a photochemical polymer is laminated. The thickness of the entire plate is about .032”, capable of being engraved up to .016".9 The platemsking process is similar to photoengraving in that the negative of the original is photographed onto the plate and the plate is then developed. However, with the Dycril plate, exposure is with ultraviolet light ins stead of arc lamps. During exposure, the image areas be- come hardened, and the plate is then.plsced in a chemical solution. The solution etches away the non-hardened, non- image areas and produces the relief plate in twenty mine utes.10 The Kodak Relief Plate, develOped in l96h by the Eastman Kodak Company, utilizes the same basic principles 9Pred Sharring, ~ccc Plant Praises Letterset With Dycril Plates," gaperboard gacgggigg, Vol. #9, No. b (April. 196“). pp- 7 ~3- 10Lons. Mu p. 59. 88 as the Dycril plate, but the plate itself is somewhat different. The plate consists of a very thin layer of a photochemical silver halide emulsion on a lacquered steel plate. A relatively thick layer of modified cellu- lose acetate is sandwiched between the steel and the emul- sion. After exposing the plate with an arc lamp through a negative, the plate is placed in an activating solution which deveIOps the image and washes away the nonpimage areas of the emulsion. The plate, washed with warm water which removes the unexposed gelatin, is then placed in,a processing machine which creates the relief by brushing away the acetate nonpimage areas with a pile fabric and solvent. The entire process takes from twenty to thirty minutes, depending upon the type of plate and the depth of the relief.11’12 It has also been reported that Time, Inc., has a photo-sensitive nylon.p1ate in the development stage which could also be used for wrap-around letterpress and letter- 13 set printing. 11Henry c. Staehle, “The Kodak Relief Plate,” Techni- cal Develo ments In The Gra hic Arts (New York: Litho- graphers and Photoengravers International Union, 1965), PP. 5‘70 12Kenneth Waughtal, ”The Eastman Kodak Relief Plate," Paperboard 2931:5135, Vol. 50, No. 5 (May, 1965), pp. Bit-35. 1310118, age “a. p. 6°e CHAPTER XVII PLATEMAKING FOB OFFSET LITHOGRAPHY Platemaking for offset lithography, since it also is a photomechanical process, is very similar to the meth- od of making plates for letterpress. The same general steps are observed: (l)preparing and photographing the original artwork, (2)exposing the negative or'positive on.a sensitized plate and (3)developing or etching the plate. As in letterpress, both line and halftone copy can be used, and the photographic technique of interpesing a halftone screen between the copy and the camera is also used for halftone ccpy. Also, since lithographic plates are easy and inexpensive to produce, only original plates are made, as opposed to the heavy use of duplicate plates for letterpress printing. If another plate is necessary, the photomechanical process is merely repeated. In gene eral, there are three classifications of lithographic plates: (l)aurface plates, (2)deep-etch plates and (3)bi- or tri-metal plates.1 Surface PlatesooLithographic surface plates are made of zinc or aluminwm, on.which the surface is grained or 1Information concerning surface, deepcetoh and multi- metal plates and platemaking is taken.primarily from H.C. Latlmer, We. pp. “3.52e 89 90 roughened. The graining is accomplished by slowly rotating the plate with wet graining grits, or abrasive sand, and steel, wood or glass marbles. The rolling marbles drive the abrasive into the plate and create a uniform, roughened surface. Rough grained plates are usually used for line plates and fine grained plates are used for halftones. The grained plate is then washed (counter—etched) with a weak acid. Finally, a light-sensitive bichromated solution is coated evenly on the grained surface of the plate in a whirler machine, and the plate is dried, ready for photo- printing. The original is photographed and the negative is placed in a vacuum frame on a glass flat, exactly the same as for letterpress photOprinting.2 The plate is then ex- posed to strong arc lamps which cause the image areas of the plate to harden, leaving the non—image areas water soluble. Following eXposure, a thin layer of lacquer and devclOping ink is applied to the plate surface and dried. Subsequent immersion in water penetrates the ink and dis- solves the soluble photosensitive plate coating (noneimage areas). The plate is then rubbed lightly under running water, and dried. The image areas are now ink-receptive 2All correcting for lithography is done on the negative before photoprinting as it is quite difficult to economically correct a finished plate. This is some- what Oppcsed to letterpress platemaking since much of the correction work is done directly on the relief plate it- IOlfe 91 and the nonnimage areas are treated with a weak acid to increase their water-receptivity. Surface plates are the easiest, least expensive lithographic plates, and are normally used for relatively short printing runs of less than 50,000 impressions. Deep-Etch glates-oTo meet the demand for lithographic plates that had a life of more than 50,000 impressions, the deep-etch plate was develOped. In.a sense, the deep-etch plate is an intaglio plate since the image areas are slightly recessed below the plate surface. The etching, however, is so slight that when.ink and water are applied to the plate, both are at the same level. The photoprinting of a deep-etch.plate is identical in procedure to that of surface plates, except that the plate is exposed through a positive instead of a negative. This is done so that the image areas will not harden, since they are to be etched away during development. The etching usually penetrates to a depth of not more than .0003". A lacquer or asphaltum coating is applied to the image areas to make them ink receptive, and the coating on the nonsimage areas is softened and rubbed off, leaving them water-receptive. Multi-getal glates-Since bi- and tri-metal plates were developed to be used in runs in excess of 500,000 they are gradually replacing both surface and deep-etch.plates, especially for long-run, high quality package printing. There are several kinds of multi-metal lithOgraphio plates 92 being used today, the most common.being: (l)c0pper- chromium bi-metal, (2)stainless steel-copper bi-metal, (3)aluminum-c0pper bi-metal and (h)ohromium-copper-steel or zinc tri-metal. “The principle of these plates is to use the capper for the image base, and the hard,nmc- corrosive chromium, stainless steel or aluminum for the 3 non-image areas.“ All of these plates are so etched to permit one metal to be inkureceptive and the other to be receptive to water. In addition to the obvious advantage of longer plate life, multi-metal plates make it possible to more faithfully reproduce halftone dots on the plate surface since it is not grained as is the surface of deep- etch plates. Step and Repeat Photocomposigg—-0f notable importance in the package label and metal can printing industry is the deve10pment of the photoprinting step and repeat, or photo- composing, machine. Also used extensively for rotogravure cylinders, the step and repeat process “can expose one negative (or positive) repeatedly many times in exact desired positions over the entire area of a plate . . . to .005" precision.“n This enables the printer to use one nega- tive of the cepy and one plate to print as many labels, cans or other repetitive cepy as will fit on the plate. 3m” p. 1:8. “Long, 22c Cite. lie 79. 93 Another important develOpment for’package printers has been the recent use of Dycril and Kodak Belief Plates for use on dry-offset (letterset) presses. These plates are discussed Chapter XVI (Platemaking for Letterpress and Flexography). CHAPTER XVIII PLATEMAKING FOR BOTOGRAVUBE Making plates to be used on rotogravure presses is quite different in.nature than for either letterpress or offset lithography, even though the same general photo- mechanical processes are utilized. The basic difference between the platemaking processes is that while letter- press and offset plates are made to be attached to the mechanical printing plate or cylinder, rotogravure plates are produced directly on the printing cylinder. This is done through the use of a carbon tissue resist which, when.photographically prepared, allows the image to be chemically etched. Rotogravure etching for package print— ing is divided into two general classifications: (l)convenp tional and (2)1ateral hard dot or halftone gravure.1 Conventional Gravure 21atemakigg-«All artwork preparation, photography and flat stripping for gravure platemaking is done in precisely the same manner as for letterpress and offset lithography, with the exception 1host information, unless otherwise indicated, conp cerning gravure platemaking is taken from Intaglio Service Corporation, g2. cit., Chapters 3-h. 9h 95 that no halftone screen is used when.photographing original continuous tone cepy: the cepy is photographed as is. Caru bon tissue, composed of layers of pigment and alkali din chromated gelatin coated on a paper backing, serves to transfer the image from the original negative to the cylinp der. The carbon tissue is first exposed to an intense arc lamp through a gravure screen only. The rotogravure orig- inal screen "normally used has a pattern of opaque square dots, separated by transparent lines . . . normally made on glass; a recessed dot pattern . . . formed by etching, and the recesses . . . filled with black pigment.”2 The exposure results in lines (usually 150-300 per inch) at right angles to each other of hardened gelatin. The un» exposed dots remain soft. The positive print of the original is then photon printed on the carbon tissue containing the screen line images. In effect, this results in using a screen to photo- graph both line and halftone copy, as opposed to letter- press and offset methods which print only halftone cepy through a screen. Since the carbon tissue, or resist, is photOgraphed through a positive, the nonnprinting areas harden the gelatin on the resist. The printing images create varying degrees of hardness or insolubility depend- ing upon the tonal values: highlights permit the greatest 2Cartwright and McKay, gp. cit., p. 157. 96 amount of light to penetrate through the positive and cause the greatest amount of hardening, shadows permit the least amount of hardening. The printed tissue is now ready to be transferred to the printing cylinder. Generally the cylinder is made of hollow steel, cast iron or aluminum which has an outer facing of pol- ished copper. The photOprinted resist is placed face down on the cylinder, wetted, squeegeed and the paper backing removed. The cylinder and resist are then.placed in an etching bath or trough containing a ferric chloride solution. The remainder of the plate is coated, or staged, with a waterproof paint or varnish. As the cylinder rotates in the bath, the solution swells the gelatin and starts to engrave the cylinder. Differential etching (etching to different depth) is ac- complished since the gelatin is differentially hardened according to the tone or line photoprinted on the resist: the harder the gelatin, the less etching. When the etch- ing is completed, dots of equal diameter and spacing but of varying dept.hhave been engraved below the cylinder surface. When ink is applied to the surface of the plate during printing, the deeper dots, or wells, will produce the dark or shadow tones and the shallowest wells, the lightest. The screen lines remain unetched and do not print. Lateral Hard Dot og_§§;f Tone Gravure Platemakiggo- For package printing, especially for halftone and color 97 work, the lateral hard dot or half tone process is preferred since it provides greater uniformity and consistency for long runs. The final printing cylinder not only contains dots of varying depth as in the conventional gravure cylinr der, but the dots are also of varying diameter. This is accomplished by photOgraphing the original in contact with a so-called Magenta screen (similar to the process of photo- graphing halftone work through a halftone screen for letter- press and offset plates), as Opposed to separately photo- graphing the cOpy and the screen as is done with conven- tional gravure. The screened positive is then photoprinted onto the carbon tissue resist, followed by the photoprint- ing of the original continuous tone positive. Etching is then.performed in the same manner as for conventional gravure e CHAPTER XIX PLATEMAKING FOR SCREEN PROCESS As with letterpress, lithographic and gravure plate- making, screen process platemaking for use in.package printing utilizes the principles of photomechanics by pho- tographing the original artwork and then, in some way, re- producing the image on the printing screen. In general, there are two basic types of producing screens photograph- icallyc-transfer and direct. Both types utilise photoprinting on a lightsensitive substance through a photographic positive or negative of the original copy. In the transfer method, the photoprint- ing is performed on an intermediate substance such as car- bon tissue, which in turn is transferred to the printing screen. The direct method, in contrast, involves coating the screen with a photosensitive solution, and then.photo- printing directly on the sensitized screen. The most com- mon transfer methods are: (l)wet carbon tissue, (2)dry car- bon tissue, (3)Ektagraph film, (h)DuPont film, (5)Craftint film, (6)Ulano Feta-Film and (7)Active Micro Photo film, 98 99 while polyvinyl alcohol and Birtex are the most common direct methods.1 Net Cagbon Tissue Transfer Screens~-In this process, the carbon tissue (similar to that used for gravure re- sists) is first prepared by sensitizing it with a solution of potassium bichromate or ammonium biohromate, and squeee geed onto a transparent flexible vinylite or film support. The tissue and support are then.photoprinted through a positive in a contact or vacuum frame with strong arc lamps. This hardens the nonpimage areas of the tissue gel- atin. The carbon tissue sheet and backing is then washed out in warm water and the tissue backing sheet removed. All unexposed (soft) gelatin is removed and the hardened areas remain on the support. The support and gelatin is then placed face up on a glass or paperboard flat which is placed beneath the screen. While still wet, the gela- tin is pressed into the screen, allowed to dry, and the support removed. 2;; Carbon Tissue Transfe; Screens~-The dry carbon tissue platemaking procedure is quite similar to the wet carbon tissue method, the only exception being that, fol- lowing the sensitizing Operation, the tissue is allowed to dry, rewetted, and placed on the support. Washing out and 1All information concerning photographic screen pro- cess platemaking is taken from Albert Kosloff, Photographfig Screen Process Printigg (Cincinnati, Ohio: The Signs of t e Times Publishing Company, 1955), Chapters 1, III, VI-XIV. 100 transfer to the screen remain exactly the same. The dry carbon tissue method was developed primarily to prevent melting of the wet gelatin while exposing under the hot arc lamps. This possibility is reduced since the tissue is dry during the photOprinting operation. Ektggggph Film Eggnsfer Screens--The Ektagraph film is a photographic film developed by the Eastman Kodak Company specifically for use in photographic screen pro- cess printing. The Ektagraph film is exposed to a photo« graphic positive and then developed in standard activators and stop solutions. The developed film is placed face up onla glass, Lucite or Plexiglas sheet, and washed out with warm water to dissolve the softened or unexposed gelatin areas. The image is then transferred to the screen by the same method used with the wet carbon tissue transfer. A solvent is then applied to the screen and the backing sheet of the film is removed. ont lm nsfe Sc e s-«The DuPont film employs the same basic principles as the Ektagraph film.with the following exceptions: (l)the film may be exposed convene tionally, in.a regular camera or through projection in an enlarger and (2)the film has a vinyl base that may be stripped off the screen following transfer and drying, withp out additional use of solvents. Ulano goto—Film Egansfer chggggy-The Ulano Foto~Film is another nonppresensitised film method. The unsensitixed film is stripped to a thick piece of paperboard and coated 101 with a bichromate sensitizing solution. The sensitised film is then removed from the paperboard and exposed by passing carbon.are rays through a positive. the film back- ing sheet, and then the emulsion.' It is then developed in warm water and glycerin, placed on a glass, and then trans- ferred onto the screen. The backing sheet is removed after drying. Active Micro gheto Zilm Transfer Screens--The Active Micro Photo film consists of a gelatin layer or emulsion coated on a vinylite transparent backing. The film is sensitized by placing it on a paperboard backing. immers- ing in.a biohromate solution, and drying. It is then ex- posed through a positive, washed out with warm water. and rinsed with cold water. Transferring to the screen fol~ lows the same general procedure of all the transfer pro- 0 ceases. P01111511 Alcohol Qirect Screens-«The polyvinyl alcohol. or PVA, process involves coating the screen with an emulsion of PVA and potassium biohromate or ammonium biohromate. The screen.may be coated either by pouring the solution over the screen, dipping the screen in the solution. or by brushing the solution into the screen. The screen is dried and then exposed through a positive or negative, which results in hardening some areas and leaving others unhardened. The screen is then.deve10ped or washed out in warm water and allowed to dry. 102 Birtex Direct Screens-The Birtex method of preparing screens is one of the oldest, being deve10ped in 1928 by Silk Screen Supplies. Inc. A coating of a gelatinous col- loid and a sensitizing agent is poured on the screen. the screen is dried, exposed to a positive, and washed out with warm water. PART IV COLOR PRINTING CHAPTER XX COLOR THEORY, MATCHING AND MEASUREMENT Color is a complex, confusing subject for most peeple. and any attempt to discuss all aspects of the many theories of color currently accepted today would be impossible. An attempt will be made. however, to ac- quaint the reader with the fundamentals of color with the hape that color process printing can be more compre- hensively understood. ht 1 ant and Color-oln 1666. Sir Isaac Newton first discovered that when sunlight passed through a glass prism at a certain angle. the so-called white light of the sun could be broken down into seven observable colors which he named red. orange, yellow, green. indigo, blue and violet. Thus, it was discovered that white light cone tains all the colors we can normally observe, and that color, at least in.part. consists of light. Today we know that visible light, such as that radiating from the sun, consists of electromagnetic waves in the 400 millimicron (#000 Angstrom units) to 700 milli- micron (7000 Angstrom units) range of the entire electro- magnetic spectrum, which. in itself, extends from 3 x 101“ 10“ 105 to 1 x 10‘“ Angstrom units.1 Each color, then, can be given a specific electromagnetic wavelength designation when separated. Colors and wavelengths in millimicrons are as follows: red, 750-610; orange, 610-5903 yellow, 590-575: yellow-green. 575~5553 green. 555-510: blue- green, 510-h80: blue, hBO-RSO: and violet, h50-h00.2 It has also been learned that physical objects con, tain certain pigments which enable them to either absorb or reflect various color wavelengths. In addition to be- ing absorbed or reflected by objects, color wavelengths can be transmitted through certain translucent objects. This then, is the basis for color. A substance or object in itself has no color, and color is not a physical substance. Color depends upon two things-~light, and the ability of a substance to absorb or transmit certain wavelengths of light. For example, an object perceived to be blue is so pigmented that when the wavelength spectrum of visible light falls upon it, all wavelengths of color are absorbed into the substance and only the blue wavelength is reflected. This wavelength of blue light is then transmitted inmo the eye where the color is created by the brain. Similarly, red glass absorbs all light wavelengths except red, which it transmits through it. ICartwright and McKay, OEe Cite. p. 71!. 2 The Research Association of British Paint, Colour and Varnish Manufacturers, Colour Surface Coati s (Teddington, hiddlesex, EngIaEdc Paint Research Station, 1956). pa 90 106 This phenomenon of light absorption and transmission through colored filters is the basis of color separation techniques used to produce color printing plates as discussed in Chapter XXI (Color Process Platemaking and Printing). white and black are not considered to be colors in the phys- ical sense, as white is the total reflection of all visible light and black is the total absorption. The dual nature of color, i.e., light and pigment, has led to considerable confusion within the graphic arts industries. Color is generally broken down into three pri- mary colors from which all colors, theoretically, can be produced. In the photographer's language, these three pri- mary colors are red, blue and green, or more precisely, orange-red, violet-blue and green. However, when discussing primary colors with the artist or printer, the primary colors are red, blue and yellow (magenta, cyan and yellow). In.ad— dition, the printer's primary colors are the photographer's secondary colors (colors which are combinations of the pri- mary colors) and the photographer's primary colors are the printer's secondary colors. Although this seems confusing, when analyzed in the preper context, the apparent paradox is easily explained. As already discussed, pigments absorb some light and reflect other light. Thus a blue object contains pigments which absorb red and yellow light and reflect blue light. The red and yellow light, when combined, form an orange-red light which is a primary light color. Thus, when red and 10? yellow pigments are combined, a secondary red-orange pig- ment is produced, which corresponds to the primary orange- red light color. In other words, an absorbed color is the exact compliment of a reflected color. Since pigment colors substract light to produce a color, mixing pigments is called a subtractive process. In contrast, when light colors are mixed, color is added and the process is additive. The artist, working with pig- ments and subtractive process, is speaking of pigment colors. The photographer, working with color filters and additive processes, is speaking of light color. Qolor ldentification--Practically as confusing to the ordinary layman as the theory of color is the way in which colors are described and identified. Colors such as magenta, cyan, blue, blue-green, yellow, pink, carmine, tan, ultra- marine, etc., are obviously not eXplicit enough to describe the thousands and thousands of colors that could theoret- ically be produced by mixing light or pigments. In attempt- ing to provide a basis for describing a large number of sim- ilar and dissimilar colors alike, several color systems have been deveIOped over the years which aid the graphic artist, the package designer, the ink supplier and the printer alike. These systems can be classified into four main types:3 (l)pigment mixture types which show the range of colors produced by mixtures of pigments and various amounts of 3 Ide. pp Bh-HZe 108 black and white, (2)printing ink types which show ranges of colors produced by over-printing primary-colored inks in different densities, (3)physical types which measure the physical characteristics of wavelength, color quality and reflectance of a color, and (h)subjective types which ar- range colors that appear to be evenly spaced. Of primary interest to the student of packaging graphics are the two latter systems-~the physical and the subjective types. The physical color systems in common use today stem primarily from the Ostwald System of German ori- gin. The Ostwald Color System, recently reproduced and used widely as the Cglor Harmony Manual (published by the Container Corporation of America), arranges colors accord- ing to color, black content and white content. It divides color into 2“ hues and 680 colors produced from these basic hues. Each of the 2b hues is arranged on.a separate sheet with the graded colors produced by adding various amounts of black and white. The separate sheets are then used to construct a color circle or wheel with complimentary colors opposite each other. The Hansell Color System is most indicative of the subjective type of system. The Hunsell system identifies all colors by number and/or composition of pigment, and are ranges colors according to three visual preperties: (l) hue, (2) value and (3) chroma. Hue is the actual color wave— length reflected from a substance such as blue, yellow, green, red, etc. Value or lightness (or tone, brightness, 109 darkness, density) refers to the relative lightness or darkness of the hue, which is the amount of light re- flected. Adding various amounts of white or black pig- sent will change the value of a pure hue. Chroma, or eat- uration, refers to the relative strength or purity of a hue; it is the intensity of the hue. Thus, we can have deep reds, dark purples, pale blues, etc. Based on this three-dimensional system, all colors can be precisely described in terms of hue, value and chroma. Color Matchiggr-The majority of package printing utilizes color in some form or another, and often the color of the package itself serves as an identification of the product or the manufacturer, e.g., the red back- ground used on the labels of Campbell's Soups and Eastman Kodak yellow. Because of the many variables involved in printing, the color finally produced on the substrate is often not the color originally planned for, or often differs from the color printed on another supposedly identical substrate. These unmatched colors are often the result of imprOper ink formulation, different pigments or dyes supplied by dife ferent ink suppliers, differences in the amount of ink deposited on the substrate because of differences in the ink, in the presses used, in different printing plants and on substrates of different formulation and absorption qualc ities. Difficulties in color matching also occur because of aetameric matches, i.e., a color match that appears to be 110 good under one type of light source, but does not match under a different light source. For example, it would be possible for a printer to use more of a certain color when printing at night under flourescent lights than was used during the daytime run when no lights were used. To avoid this, designers and printers often utilize several sources of light when designing or printing, or use specially- designed lights which eliminate metameric matches by dupli- cating all types of light and color temperatures commonly in use. Color matching, then, is generally performed by the ink supplier, the designer or the printer. Matching is a complex operation and can be performed adequately only if the Operator is given adequate information concerning the printing variables such as: (l)the type of ink required, (2)the type of press to be used (the process and whether it will consist of several single-color presses or a single multi-color press), (3)the time between printing of each color, (h)the tackiness of the inks used, (5)the substrate to be printed, (6)0vercoating of wax, varnish or plastic on the printed substrate, (7)fineness or coarseness of the halftone screen, (8)use of antioffset sprays or treatments, (9)gluing, cutting or folding Operations and (lO)heating devices used.“ The printer, designer and the ink supplier u Weldon R. Coate, "Ink For Packaging," Good Pack i (Western Packaging Yearbook), July 1961, p. 9 lReprinti. 111 must constantly be in contact with each other in order to assure proper color matches over a period of time. Color geasurement-oihe process of telling if a color is matched, why it does not match (if it is not matched) and by how much it does not match is called color measure- ment. In general, there are two basic systems of color measuring devices: (l)the colorimeter and (2)the spectro- photometer. . The most common type of colorimeter used for color matching of packages and packaging materials is the photo- electric colorimeter which "consists of a light bulb, a sample holder, colored glass filters--called the tristu- mulus filters--a photoelectric cell . . . and a meter."5 The photoelectric colorimeter measures the amounts of red, green and blue in a colored sample by reflecting the light off the sample, through the tristimulus filters and past the photoelectric cell, which converts the light energy into electrical energy to run the meter. The calorimeter is quite useful in describing the red, blue and green com- ponents of a color, but cannot distinguish a metameric match. To help in matching colors which will not produce a metameric match, the spectrOphotometer was developed and is used either by itself or in combination with a colorimeter. 5Leonard A. seiner, An Introduction to Color and flea- surement (Nutley, New Jersey: Atlantic Chemical Corporation, $93550 pa 3- 112 In addition to calculating the amounts of red, green and blue necessary to match a certain sample, the spectro- photometer also obtains a ”spectral reflectance curve showing how the preportion of the incident light reflected from the test panel varies through the spectrum from blue to red."6 The spectral reflectance curve eliminates meta- meric matches since it can create a match that "has the same reflectance curve as the sample throughout the spec- trum so that it will remain an exact match under every type of lighting."7 6The Research Association of British Paint, Colour and Varnish Manufacturers, cg. cit., p. 52. 72mm. 1» 57- CHAPTER XXI COLOR PROCESS PLATEMAKING AND PRINTING Now that on.appreoiation.hss been gained for the phenomenon of oolcro-ite nature, how it works, why it works, and its terminology-ca discussion of color pro- cess platemaking and printing can be undertaken. making printing plates from color artwork, in.oontrast to one- color line or halftone copy, differs only in.the photo- graphic processes and the number of plates required to print the final reproduction. All of the other steps, such as artwork preparation, photoprinting, etching and finishing are basically the ease with aincr exceptions that need not be considered for this type of discussion. The discussion centers around threee and four- color printing, although printing with acre than four colors is becoming increasingly popular as tastes in.pack~ aging graphics are becoming more sophisticated and pro- cesses becoming more highly dewelcped. Discussion of four- color printing will suffice, however, since only the nus, ber of color separations and plates required for aultio color printing is different; the theory and practice are identical. 113 11“ The basic principle of color platemaking is color separation and reproduction. This involves starting with the original color work, photographing it through a series of colored filters which separate it into several colors, asking a single plate for each color, and printing each color separately to reproduce the original color. In general, color process platemaking inrolwes the following steps: (l)preparation of the original, (2)sepa- rating each basic color in the original into the three pri- mary pigment colors, (3)ccrrecting the resulting color separation for color fidelity, (b)naking positive prints from the color separations, (5)phctographing the positives through a halftone screen and (6)photoprinting and finish- ing. Original Color Copy ggeparationp-Color copy can be either line or halftone cepy that is produced in.acrc than one color. Generally, however, color capy consists of full- color, continuous tone copy, as most color line work can be mechanically separated and need not go through the photo- graphic process of color separation. Continuous tone color copy includes such things as “oil, water color or tempera painting; the color transparency: and the photOprint in full color, such as oarbrc, chromctcne, dye transfer, imbibition, and wash-off relief."1 Transparencies are generally prefer- red over prints as detail and color value is often lost in the printmaking process. 1"I..ine, Halftone and Color“, (American.Photoengravers Association, 1959), p. 25. 115 Preparation of color originals is usually no more critical than that of preparing line and halftone copy with the exception that the use of colors of extreme sat- uration or lightness should be carefully weighed against- the increased costs of additional separation negatives required to faithfully reproduce the desired tone. Color Separation Negatives-carter all original ccpy has been satisfactorily prepared, the next step in produc- ing color printing plates is to make color separation nega- tives. The process of color separation takes advantage of the theory that, in effect, all colors can be created by mixing only three basic colorso-red, yellow and blue-«the three primary pigment colors. By reversing this concept, printers have found that all color copy can be reduced to the three primary colors, from which three plates are made and used to reproduce the original work. Thus, color sepa- ration involves starting with the original continuous tone, multi-color ccpy and separating all its colors into the three basic primary colors-omagenta, cyan and yellow.2 Color separation is performed by photographing the original several times, each time with a different filter placed between the original and the camera. The filters generally consist of dyed gelatin between two pieces of 2As previously mentioned, most color printing today makes use of four colors. Black is added to the three pri- maries to give more faithful reproduction of dark tones and lhfidlflge 116 glass and serve to eliminate all colors except one (either magenta, cyan or yellow) to be recorded by the camera. For example, to produce the yellow printing plate, the ccpy is photographed through a violet, or violet-blue, transparent filter. The color of the filter, it should be noticed, is a secondary pigment color (cyan plus magenta) and also a primary light color. As such, when the electromagnetic light rays from the original pass through the filter, all colors except yellow are absorbed by the filter, and only yellow, or those colors containing amounts of yellow, will be photographed. Similarly, a green filter is employed to produce the magenta plate and a red, or orange-red filter is used for the cyan.plate. When four-color separation and printing is desired, a special yellow filter is used to eliminate all but the dark tones from photographing. Colgr Corrections-Color correction is necessary since, although theoretically possible, it is practically impos- sible to achieve exact color rendition through the photo- graphic technique of color separation. Accordingly, the photographer must estimate the amount (density) of each color contained in the original and correct the negative accordingly. Although several instruments have been.develcp- sd to help in the analysis, color correction is still large- ly dependent upon the inherent and acquired skill of the photographer. After the initial color density estimates, mechanical color masks are placed in the camera and the 117 original copy is photographed through the conventional color filters.3 Separate color masks are used for each color separation negative and correct the final negative so that the preper amounts of color will be printed when the color densities are considered. Color correction is generally performed by a skilled photOgrapher before the color separation negative is made, but often it must be employed following the initial separation as its need be- comes apparent. Additional cclor ccrrection.may be necessary follow- ing the platemaking Operation when the proofing Operation shows its necessity because of inherent inability of the ink or substrate to faithfully reproduce the colors in the original. This is always a manual correction.process, as a skilled and carefully trained etcher blanks out or etches parts of the plate needing correction. In recent years, color correction has been greatly simplified. Several devices have been developed and com- mercially introduced which electronically correct originals and produce either color separation negatives or positives, completely color corrected. These electronic color scene ners, as they are called, which produce corrected color separations from either original copy, negatives, or posi— tives, generally utilize some type of photoelectric tube 3The theory of color correction is quite involved, and the reader should only be aware that it does exist and that color separation is not perfect. 118 or photo-cell which distributes the separate colors taken from a spot of white light on the ccpy. At least one de- vice is capable of producing electronically-scanned, color corrected letterpress photoengravings directly from the capy. Color Halftone Negatives-oflalftone printing plates must be used to reproduce the continuous color tone of the original. Accordingly, each color corrected separation neg- ative must be re-photcgraphed to produce a series of posi- tive prints. The positives are then photographed through a halftone screen Just as they are in normal halftone plates land both line and halftone rotogravure plates. (It is pos- sible to photograph the original through the filter and the halftone screen to produce a direct halftone color negative, but this is generally not done since “the indirect method . . . permits greater photographic control of color separa- tion, which must otherwise be performed by the etcher and finisher."h) In order to establish preper blending of the inks during printing, and to prevent a moire pattern from occur» ring, the halftone screens are placed at different angles from each other during the halftone photographing process. For most letterpress and lithographic plates, the screen for each color is separated by 30 degrees for three-color (#5 degrees for cyan, 75 degrees for yellow and 105 degrees 4”Line, Halftone and Color," cp. cit., p. 30. 119 for magenta), whereas for four-color printing, the halftone screen for black is at 45 degrees, 60 degrees for yellow, 75 degrees for magenta, and 105 degrees for cyan. 0n the other hand, the following screen angles are recommended for three-color rotogravure plates; yellow, 15 degrees; magenta, 30 degrees; and cyan, #5 degrees. These screen angles for four-color rotogravure are: yellow, 11 degrees; magenta, 22 degrees; cyan, 33 degrees; and black, #5 degrees. The screen angles for rotogravure are different and less critical than those for letterpress or lithography since the ”marked moire patterns . . . produced when rows of dots are printed at approximately the same angle . . . is (are) less likely to show in rotogravure because the dots are less sharply defined owing to ink flow."5 Color Plates--Following the preparation of the half- tone negatives, color printing plates or cylinders (one for each color) are then produced in the conventional man- ner either as photoengravings, offset plates, rotogravure cylinders, or screens. As mentioned earlier, some correc- tion is generally necessary at this stage before the plates are completely ready for the press Operation. when on the press, each plate or cylinder deposits ink on the substrate. Thus, when the inks are blended on tap of, or next to, 5Cartwright and McKay, 02. cit., p. 93- 120 each other, the eye sees the print exactly as it was originally prepared. Color Printing Presses--The printing presses previous- ly described in Chapters IV-X are used primarily for one- color printing. In general, they involve the use of one impression cylinder or plate; one printing plate, cylinder or screen; and one supply of ink. In theory, if it were possible to control color register accurately, multi-color printing could be done with any of these presses by running the substrate through one press for one color, through an- other press for the next color, and so on. Obviously this method has both time and economic limitations which render -it infeasible for most package printing. Accordingly, several general types of presses have been.developed which incorporate several printing units into a single color press which allows a substrate to pass through several units, printing one color after the next. Yellow, red, blue, then black (if four-color) is the pre- ferred sequence of colors for most presses, although this sequence may be altered or added to if the situation so dictates. Multiple printing units, multi-color presses generally fall into three categories: (1) ineline, (2) stack and (3) central or common impression cylinder. The use of each depends upon the printing process itself and the sub- strate to be printed. 121 The ineline press is probably the oldest and.mest common type of color press in use today. The press, quite simply, consists of several printing units arranged in.a straight, horizontal line, so that a substrate is printed with the first unit, passed to the second.unit, printed in a second color, passed to the third unit, etc. Theoretical- ly, as many printing units as colors of ink desired could be utilized, space permitting. Although ineline presses are common for all the major printing processes, rotogravure and screen are the only ones making almost exclusive use of it. Ineline presses are the only practical type of press to be used for multi-color printing on thick, heavy sheet materials that cannot be curved or bent, and for finished containers such as cans, Jars and bottles. The stack press is merely a modification of the ine line press. It is, in.offect, a vertical inaline press developed primarily for web-fed substrates and to reduce the space needed for conventional, horizontal ineline presses. The stack press generally consists of several printing units that print the web as it travels upward, and several that print during the web's downward path. Flexo- graphy, because of its adaptability to web-fed materials, makes extensive use of stack presses. The central impression cylinder, common.impression drum, or common impression cylinder press is used extene sively for letterpress, flexographic and offset lithographic 122 multi-eolor printing or web-fed materials. It consists of, as its name implies, of a central impression cylinder, around which are arranged a series of ink fountains and printing cylinders. The web or material is fed between the first printing section, printed, carried on the impres- sion cylinder to the next printing section, etc. The only limitation to the number of colors that can be printed is the number of printing sections that can be placed around the cylinder, which, of course, depends on the size or the cylinder. CHAPTER XXII PRINTING INKS The selection of the proper ink for printing a package or packaging material is not a simple matter; it is a science in itself as a multitude of variables must be considered before the decision is made. The sub. strate; the printing process to be used: the colors desired; qualities such as gloss, skuff resistance, fade resist- ance and color fidelity; coatings on the substrate; and post-printing Operations such as glueing and folding must all be carefully thought out before the proper ink can be chosen. "In the last 25 years, printing ink technology for the packaging field has made more progress than in all the years . . . since the invention of printing."1 Making use of the technological advances in the manufacture, theory and use of printing inks, the packaging graphics artist can now be relatively sure that the right ink will be used to produce the desired colors, reproducing the desired characteristics of the original design. lcoate, op. cit., p. 1e 123 124 Composition of Printing InksZ-oAll printing inks, whether used to print on paperboard, metal, glass or plastics, by letterpress, rotogravure, screen process, or offset lithOgraphy, consist of two major elements and one or more supplementary components: (1) vehicles, (2) pig- ments or dyes3 and (3) miscellaneous ingredients used to create special effects or desired ink characteristics. The pigment is the solid portion of the ink and produces the actual color of the ink when.printed on the substrate. The vehicle is a liquid and is used to retain the dispersed pigment until the printing operation is performed. After the printing impression is made, the vehicle is dried from the ink either by oxidation, evaporation, penetration or precipitation, and the pigment is retained on the sub- strate. Various miscellaneous compounds are added to the pigment and vehicle to aid in the drying process or to assure satisfactory pigment~substrate adherence. Printing gnk Vehicles-aThe type of vehicle used depends to the greatest extent upon the method of drying to be utio lized. The method of drying, in turn, depends largely on the substrate composition and the printing process used. For example, a different type of vehicle would be required 2Host of the information concerning printing inks is taken from "Printing Ink Handbook" (New York: National Association of Printing Ink Makers, Inc., 1958). 3Only pigments will be discussed at this point as most inks contain pigments in preference to dyes. Dyes will be discussed separately. 125 of an ink printed by letterpress on neWSpaper stock than one for ink printed on a plastic film by flexography. News- paper stock readily absorbs the vehicle, while plastic mate~ rials, being relatively nonsperous, must be printed with inks having vehicles capable of evaporation drying. Also, since letterpress prints from raised metal surface plates, the ink must be relatively viscous and tacky while, for flexography, the ink used is generally quite fluid. When an ink is to be dried through penetration into the substrate (absorption), the vehicle is usually a non, drying oil derived principally from petroleum and rosin substances. Since most absorption.inks are used for news- paper stcck, tissue and other soft, absorbent substrates, they are only rarely used for package printing today. Oxidation drying inks, however, are used extensively for both letterpress and offset lithographic package print- ing. The vehicle commonly consists of a drying oil which causes oxidation drying by first absorbing oxygen from the air, then hardening or polymerizing into a solid. Although the most widely used drying oil is lithovarnish (a processed linseed oil), other drying oils commonly utilized are either synthetic or processed from China wood, cottonseed, perilla, soya beans, petroleum, fish and resin. Rotogravure and flexographic inks for printing on paper and other flexible packaging materials usually dry through evaporation of a solvent vehicle. These solvents 126 generally consist of low-boiling point hydrocarbons,- lacquers, Spirit compounds, water or other rapid drying evaporation solvents used in connection with various gums or resins. In addition, various heat-set, evaporation drying inks containing high-boiling, slow-evaporating pe- troleum oils and solvents, are used to a limited degree for letterpress and lithographic printing on packages. Other inks with special vehicle systems are also used for some package printing applications. Some of these are: (l)moisture~set inks containing resins insoluble in water, but soluble in glycol solvents, and dry by precip- itation of the glycol-absorbed pigment upon application of water spray or steam, (2)wax-set inks, also dried by precip~ itation of a solvent-soluble resin which is not soluble in the solvent-wax system, (3)quick~setting inks having a balanced vehicle of resin, oil and solvent which dries by a combination of absorption and oxidation, (b)water color inks consisting of soluble gums dissolved in.water or glycerin and (5)cold-set inks consisting primarily of wax and resin which are applied hot, but set when cooled on the substrate. Printing Ink filaments-cPigments are the residues left on the printed substrate after the vehicle is removed from the ink. The pigment solids can be classified as either black, white, organic color or inorganic color. Black pigments are generally produced from the soot collected after the incomplete combustion of natural gas 127 or oil, and are commonly called channel, or carbon black; furnace black; lamp black; and mineral black, depending up- on the fuel burned and the type of furnace or burner used. White pigments, in contract, can be either opaque or transparent. Opaque white pigments are generally made from such compounds as titanium dioxide, zinc sulfide and zinc oxides, whereas other compounds such as alumina hydrate, magnesium carbonate, calcium carbonate and certain clays are used to produce transparent whites. Both white and black printing inks can be synthetically produced. Such inks are generally classified as organic pigments. Inorganic color pigments are derived primarily from natural minerals or mineral compounds. A few of the com- mon.inorganio color pigments are: yellow and yellow-orange from lead ohromate compounds; yellows, oranges and reds from cadmium selenide and cadmium-mercury compounds; vermil- lion.from red mercury sulfide; blues and greens from iron compounds; and earth colors such as ochre, sienna and umber. Organic color pigments are generally synthetic chemie cal compounds and are so called since they usually contain carbon atoms in their molecular structure. Originally ob- tained from living matter such as plants, and later from coal tar derivatives, organic color pigments are often preferred over inorganic pigments as they offer less 128 abrasiveness, higher color value, greater color range and have more brilliant colors.“ Miscellaneous Printing Ink Elements-aim addition to the basic vehicles and pigments, printing inks contain var» ious compounds added to improve specific characteristics of the ink. Driers, consisting of metallic soaps of lead, manganese and cobalt or compounds of calcium, iron, ccpper, sine or zirconium, are incorporated into many inks to act as catalysts by Speeding up the oxidation drying processes. Paraffin wax, beeswax, microcrystalline wax, polyethy- lene and other waxes are commonly added to inks to prevent ink setoff and sticking, and to improve skuff resistance. Various greases and other lubricants are often.uti- lized to aid in the distribution and transfer of ink on the inking rollers, and to reduce tack to permit faster ink set— ting. High boiling solvents, thin-bodied oils, and thinners to hasten ink setting qualities; body gum and binding var- nish to add viscosity, reduce emulsification, improve dry- ing and to prevent chalking; antioxidants to reduce exces- sive, premature drying; corn starch to prevent setoff: and surface active agents to increase wetting and dispersion, are other components of printing inks frequently employed. Printing Inks gor Packaging Papers-~Much paperboard stock is printed with oxidizing type inks consisting of a ”Cartwright and McKay, op. cit., p. 237. 129 synthetic resin in heat-bodied linseed oil. This type of ink dries rapidly to a hard surface, and is generally considered to be "resistant to scuffing, scratching, rub. bing, and fading during the normal handling period."5 Cor- rugated board and kraft paper are generally printed with free-flowing, quick-drying ink which frequently contains a solvent-dye system as Opposed to a solvent-pigment system. In addition, glycol-based, moisture-set inks are frequently used for both paperboard substrates and corrugated board, as the ink has the additional advantage of being rela- tively odorless. Vegetable parchment and greaseproof paper inks must usually be heavy and tacky, and especially when the paper is used to wrap greasy food products such as butter, mar- garine or bacon, must be odorless and non-toxic. Erinting Inks {or Celloghane, Plastics and Metal:- since the surfaces of transparent plastics and cellulosic films, rigid plastic containers, and metal containers are generally impervious to fluids, the ink vehicles cannot be absorbed into the material, and must therefore be dried by either evaporation, oxidation or both. Even though inks must be formulated for each specific material, most inks used for cellophane, polyethylene and other plastic and metal foils contain a high concentration of pigment in a relatively fluid vehicle with special components to improve 5§rintigg Ink Handbook, op. cit., p. 15. 130 ink substrate adhesion. Inks for metal containers also usually have additives which impart gloss to the printed can, and others to allow post-printing heating Operations. Letterpress Inks-~Letterpress inks are generally I considered to be of moderate tack and viscosity, as the ink must adhere to the raised surfaces of the rigid relief printing plate or cylinder. As it is quite viscous in com- parison to inks used for other major printing processes, letterpress ink usually deposits a thicker layer of ink on the substrate. Because of this, the ink can be formu- lated with less expensive pigments containing less color value. The viscosity and tackiness of the ink, furthermore, is dictated by the type of press utilized. With flat-bed cylinder presses, for example, ink with a fairly heavy con, sistency is required, whereas on.high~speed rotary presses, it is generally much more fluid since the ink must be fed under pressure to the rollers that distribute it on the revolving printing cylinder. The majority of letterpress inks used for package printing are the oxidation type since much letterpress printing is done on paperboard, which does not readily ab- sorb vehicles. Moisture-set precipitation type and heat~ set evaporation type inks are also used to a limited extent. Flexographic Inks-«Flexographic inks are formulated more for the types of materials run.on flexographio presses than for the process itself. Since its main application is for flexible packaging materials, almost all flexographic 131 inks are formulated to dry by evaporation, as the plastic and metal foils cannot absorb the vehicle readily. Flexo- graphic paper printing inks, however, often combine evap- oration.and penetration.type inks. The colorant component of flexographic inks can be either a pigment or a dye. Pigments are not soluble in the vehicle, but are dispersed within it, whereas dyes are soluble and form a dye-solvent solution. Flexcgraphic pig- aent inks are becoming quite pcpular, but the brilliant colors and special effects created on transparent fills and.netal foils by dyestuff inks accounts for the fact that dyestuff inks are the most popular today. Water, ethyl alcohol and pclyamide are the most widely used solvents for flexographio inks. Offset Lithographic gnks-oBecause cf the water-oil nature of lithographic printing, all inks used must be formulated so as not to run.or bleed when the printing cylinder is moistened during the printing process. Also, chase a relatively thin.layer of ink is deposited on the substrate, special care must be taken.to use ink which is strong in color value and has high tack properties. The primary inks are usually dried by oxidation using lithe varnish drying oils, although a oombinaticn.of the lithe varnish with synthetic resins and petroleum solvents al- lows drying by penetration or evaporation for special appli- cations. In addition, quick-set and heat-set lithographic 132 inks are becoming increasingly pOpular for printing on paper and paperboard. gotogravure ggkgr-since the rotogravure cylinder must contain the ink in intaglic cells, the ink used must have enough substance to allow it to be drawn out of the cells and onto the substrate. It must also be volatile enough to dry quickly and not be of such composition that it will adhere to the surface of the printing cylinder. The pig- ment be very finely ground so as to prevent it from scratch- ing the cylinder during the doctor blade operation. Rotc-‘ gravure inks are normally classified as either Type A, B, c, D, E. r, w or x.6'7 Type A inks consist of naphtha or naphtha-coal tar solvents and hydrocarbonpscluble resins. They are rarely used to print packaging materials, but are quite popular in the magazine and newspaper publishing industries. Type B inks are used to print highly-calendered, starch-coated papers (mostly used for magazines), and generally consist of higher quality resins, ethyl cellup lose binders to improve ink-substrate adhesion, and are- matic solvents. Type C inks use more expensive nitrocellulose resins and ester, alcohol, aromatic hydrocarbon or other lacquer écartwright and McKay, op. cit., pp. 231-2. 7Gravure Technical Association, Roto ravure nk (New York: Gravure Technical Association, 1935’, pp. 15-22. 133 solvents. Used primarily for non-absorbent stock, Type C inks are used extensively for printing flexible plastic and metal packaging materials. Type D inks are generally thermOplastic inks con- sisting of polyamide resins with an alcohol and aliphatic or aromatic hydrocarbon solvent, and are "used on foil, paper, boards, polymer-coated cellOphane, polyethylene, mylar and on.many other specialty films."8 Type E inks are also used for flexible packaging materials as well as for label and paperboard stock. They consist of alcohol-soluble resins in alcohol or alcohol- ester solvents. Type T inks consist of Special synthetic resins in straight aromatic hydrocarbon solvents. They are used extensively for nitro—cellulose coated collaphane, soap and bread wrappers, and label and paper laminates. Type W inks are used to a limited extent for food containers and plastic films, but find most use in other specialty applications outside of the sphere of packaging. These inks consist of natural or synthetic gun in a water or waterwalcohol solutionu Type x inks are miscellaneous inks not fitting into the other categories. They are specialty inks, formulated for specific applications. Many plastic films are printed with Type X inks. 81bid., p. 21. 13“ Screen Process Inkso-host screen.process inks used to print on packages are quite viscous and apply a thick layer of ink to the substrate. It has been estimated that "the coating (of ink) may be 10 to 20 times as thick as in.letterpress printing.”9 Practically all types of vehicles, binders and pigments may be used in screen.pro- cess inks, and fluorscent inks have been especially suited for screen process. Because of the thickness of the ink, extensive use of driers and drying agents is made. “MM- 9Kosloff, ghgtographic Screen Process Printi , Op. cit., p. 3. PART V DECORATING PACKAGES AND PACKAGING MATERIALS CHAPTER XXIII INTRODUCTION TO DECORATING PACKAGE SUBSTRATES There is no clear-cut method of determining the process used to decorate a package or packaging material as many variables must be analyzed in order to properly evaluate the alternatives and to arrive at a proper deci- sicn. Obviously, economics play a major role in.the final decision. One process can prove to be the most economical choice for short-run.printing operations, while if long- run.printing is necessary, another process might be the most feasible from an economic standpoint. The quality of the printed reproduction also is a major factor. Some processes produce fine quality half- tone work, whereas others have the advantage of producing vivid, high contrast colors, but not high quality half. tones. The substrate to be printed also must be considered. Many substrates simply cannot be printed by a particular method, while other methods are ideally suited for the substrate. .As Long so succinctly states: 136 137 as in most competitive fields, there are wide differences of Opinion as to the advantages and disadvantages, and the future prospects of the various printing processes. Most will agree, however, that properly used, every pro— cess has certain advantages, and all will be around for a long time. In the following chapters, each major group of packages or packaging materials will be discussed from the standpoint of the process normally used to decorate, why the process is chosen, and its advantages and disad- vantages as a decorating method. No attempt will be made to offer an opinion as to which process is the best (if, indeed, an opinion could be made) for a particular type of package substrate. lLong, MN 130 20- C Hf. PTEE XX IV DECORATING PAPERBOAIL'J AND CORRUGATED CONTAINERS Paperboard is used in packaging primarily for folding cartons and rigid set-up boxes. Corrugated paperboard, of course, is used for corrugated shipping containers and dis- plays. Since the majority of retail setdup boxes are overu wrapped with a printed paper, printing for set-up boxes is included in Chapter XXV (Decorating Flexible Packaging Materials), while folding cartons and corrugated containers are covered in the following discussion. Ecldigg Carton Printing-~Lettsrprese was the first printing process used to print folding cartons as substan- tial amounts of cereal and cracker boxes were printed in the late 19th century. All major printing processes have subsequently been adapted for folding carton.printing, with rollofed, ineline cutting and creasing operations on rotOgravure presses showing great promise for future appli- cation. J.M. Simeone, representing a large printing as» chinery manufacturer, has stated that “'in the east north- central states . . . whose printing capacity (for folding cartons) represents 25.9 percent of the country's total, 31.7 percent is devoted to letterpress printing capacity, 138 139 18.6 percent is devoted to flexOgraphy, 23.7 percent to offset, and 2h.l percent to rotogravure.”1 host letterpress folding carton production today is done on large, sheetofed, flat-bed cylinder presses, gen- erally equipped with an extra platen containing a form to die-cut and crease the container immediately following the printing Operation. Used extensively for heavy, relative- ly thick, folding carton stock, straight or flat-bed letterpress is being challenged by high-speed rotary letterpress, wrap-around letterpress and letterset methods for use on glossy, coated, thinner stock. The greatest advantage of the latter methods of printing is the reduced make-ready time, i.e., the time it takes to prepare and cor- rect the printing plates and the press to insure prOper, clear impressions. It has been stated by F.G. Barber, manager of a folding carton.plant, that on one particular wrap-around letterpress run on folding cartons, "the make- ready and printing time for h1,000 impressions equalled the time it would have taken to simply make-ready the same job on a flat bed letterpress."2 Offset lithographic printing has made definite in» roads in folding carton printing "in the last few years, I'Plexographic Printing, Where Does It Stand? What‘s Ahead?,“ Techno 0 ca Develo ments n The Gra h c A2158. OE. cgtc. p. e 2"Wraparound Letterpress: A Growing Acceptance,” Technical DevelOpments In The Graphic Arts, Op. cit., p. e mo much of it at the expense of flat bed or rotary letterpress printingd’ Some persons estimate that offset lithography is used to produce approximately 20 percent of all folding cartons, by dollar volume. One of the reasons for its inp creased share of the folding carton.printing market is that higher quality halftone color reproduction can.be obtained by offset than by letterpress because offsetting the image on.a rubber blanket permits greater conformity of the half- tone to the uneven.board surface. In.addition, the low cost of platemaking allows greater freedom to make copy changes as new plates can.easily be produced.“ These sane advantages apply to the letterset, or dry offset, process. Flexogrsphy is used for a substantial amount of folding carton printing, especially for maze and plastic- coeted milk cartons and for beverage carrier cartons. It is especially useful when the press is furnished with web- fed, ineline rotary cutting and creasing devices. The advantage of combining nebufed cutting and creas- ing with the printing operation has led to the unparalleled growth of rotogravure printing of folding cartons. Although web-fed cutting and creasing units for rotogravure presses were first "designed and built by Mr. Louis Chambon.. . . in 1888 . . . it wasnPt until 1900 . . . that a press of A 31:013. EEO Olte. p0 70e “gains. pp. 70-71e 1&1 this type was publicly exhibited,“5 and not until the late 1940's that one was purchased by a folding cartonprcduoer.6 In addition to the advantage of ineline die-cutting and ‘ creasing, other advantages of gravure for folding carton , printing are highpspeed, multi-color printing with instant drying, odor-free inks that produce high-quality, fine screen process color, with thick ink films and strong 7 colors. Large volumes of cigarette, candy, soap and deter- gent, cereal, fccd and carry-hone beverage cartons are cur- rently printed by gravure.8 Although relatively uncommon, sometimes folding oar- tons utilize more than Just one of the printing processes to obtain the desired graphic design results. ‘An excellent example of this is a carton.produced by Arkay Packaging Corporation for Dorothy Gray, Ltd., of New York for three lines of toiletries and cosmetics. The cartons consist of large color areas printed by letterpress to assure strong color throughout the run, a halftone illustration.printed by offset lithography for fine detail and shading effects,' and hot roll-leaf stamped filigree band and fragrance 5Arthur F. Goat, "Cartons By Gravure,“ (Reprint from m. 1963). p- 1- 5134., p. 5. 7Long, op. cit., p. 100, (from FAdvantages of Gravure {n goldingICarton Production,” gggvurg, Vol. 2, no. 7 (July, 95 e Ps 5° 0 8140338. 22. Bite. pa 1020 1&2 identification to achieve special decorative effects.9 gopppgated Container Priptipg-Corrugated container printing has historically been done by letterpress with special rubber printing plates. Technically, this is not flexography as thick, oilnbased inks are used as opposed to the thin, rapid-drying, water or alcohol-based inks used for flexographic printing. The oil-based inks are used in preference to the transparent fluid inks, primarily be- cause the "transparent . . .ink . . fails to cover imperfec- tions in corrugated board."1° Also, it has been.noted that "customer acceptance of flexographic (corrugated) printing has been slow . . . because of the trade's emphasis on high gloss printing,"11 which flexography’s brilliant colored inks cannot readily produce. It has been predicted, however, through recent developments in flexographic presses and inks, "that within five years (as of l96fi) half of all new printing machines sold for the manufacture of corrugated containers will be flexographio.'12 host rotogravure and offset printing for corrugated containers is done, not on the corrugated sheet itself, but 4“ 9“Plus In hulti-Color Printing," de‘ ack , Vol. 38, No. 2 (October, 196b), pp. 120- +. 10"Corrugated Printing Progress Report," Consumer Packagppg (December, 1960), p. 57. 11"Flexo Printing Outlook: Bright," a erboard ack- gggpg, Vol. #9, No. 7 (July, 1965), p. 70. (From an ad- ress by 8.3. Greenwood). lzlblde. p. 68a 1&3 rather on the liner which is pro-printed, then combined to form the sheet. This type of printing is not done extenp sively, but does have application for long production runs where high quality reproduction is desired. Also being used to a limited extent is screen.process printing which has the advantage of brilliant color intenp city, but lacks sufficient speed (present presses can ob- tain press speeds of up to 2000 sheets per hour) to be used extensively. Some feel, however, that screen process print- ing on corrugated will increase in the future and note that "it is gaining more and more for point of purchase dis- plays, and there are increasing instances of container appli- cation."13 6 13" Corrugated Printing Progress Report.” Mn pe 5 e CHAPTER XXV DECORATING FLEXIBLE PACKAGING MATERIALS In general, flexible packaging materials consist of paper, metal foils and transparent films such as cello- phane, polyethylene and other polyolefins. Flexible pack- aging materials are used to make a wide variety of wraps and overwraps, bags, pouches and labels. Paperwraps, bags and labels: cellophane; foil and plastic films, and the methods of decorating each are discussed below. Paper WrapI Egg and Label £rintipg--It would be virtually impossible to pinpoint a particular printing method as the primary process for decorating paper. In fact, all of the major processes, from letterpress to screen process, are used in some way or another, to deco- rate packages made from flexible paper materials. The pro- cess used, however, usually depends upon the end use of the paper, i.e., whether it will be used for wraps, bags or labels. The earliest printing on paper bags was done by letterpress. Paper bag printing was noted to be estab- lished as early as 1618.1 From that time on, letterpress Imus. MN I» 15- lhh 1H5 was the principal means of printing paper bags until the early 20th century when flexography was developed. And, even today, very little bag printing is done on offset or gravure (primarily because fine halftone quality is not generally required) as it is done either by rotary rubber plate letterpress or flexography. wraps and labels have been.historioally printed by letterpress, but a trend has been noted of 'a continual movement from letterpress printing to rotogravure for wraps and lithOgraphy for labels, since these processes provide both speed and fine-detailed reproduction."2 The basic rea- son that "1ithography has been the leading process for many years"3 for label printing is because "the step and repeat machines, and the 'gang run' have enabled offset lithogra- phy to produce paper labels extremely efficiently.'h Roto- gravure, in contrast, derives its advantage for printing paper wraps from the fact that "the oircuaferenoe of the printing cylinder can be varied to fit the individual Job . . . , (so that) a wrapper . . . of any size can be print- ed without waste, in sheets or continuous rolls.'5 Offset and gravure label and wrapper printing presses today are largely sheet-fed operations as very few rollofed presses Z'Shifting Trends In Printing-”Part 2. Flexible Hate- riaisé” Modern Pacgggigg, Vol.35, No. 1 (September, 1961), 1). 1a 31.0115, 020 01!. Do 690 u IEL.‘ 5Cartwright and HoKay, w... p. :1. 1&6 have been developed for use. Letterpress printing, in addition, still remains a factor in label printing as it is used quite extensively for printing bread labels and wraps. Celloppgpe PrigtipgooThe first commercial printing on cellophane is reported to have been done by converted letterpress by the Milwaukee Printing Company (now Mil- print, Inc.) sometime in the early 1920's. Soon after, the gravure process was perfected for cellophane print- ing and then, the flexographic process was adapted. As Ancted earlier, it was the advent of cellophane that con, tributed much to the early success of flexographic print- ing as a major process. Today, almost all cellophane printing is done either by flexography or rotogravure. Both have the distinct ado vantages of variable diameter printing cylinders, high speeds and capabability of roll-fed printing. Gravure generally receives preference when a large quantity of cellophane is desired or when fine halftone or color repro-_ duction is called for. Flexography remains primarily for short to moderate runs that may require frequent copy changes. In addition, extensive research is currently develOping new and better rubber halftone plates for flexe- graphio printing. Walk! with cellophane, most foil printing for wraps and labels is done by gravure and flexography as the process and the inks used "have proved well-suited for 1h? the noneabsorptive surface of foil, and the high speed roll printing of these two processes have made them the 6 Again, as with cellophane, "where halftone work, color process most widely used foil printing methods by far.” or especially long runs . . . are required, gravure print- ing is used"? in.preference to flexography, and it has been estimated that "90 percent of the printing of foil packaging materials”8 1s done by rotogravure. A trend has also been noted for printing foil with letterpress and lithography9 for "short or medium size runs for packages, wraps, labels and the like."10 Most letterpress and offset foil printing is done, however. on sheet fed presses, although some deve10pmsnt work for roll fed offset and letterpress foil printing is being done. Even so, the process has the disadvantage of nonpvariable cut-off lengths due to the fixed cylinder diameters. Plaspic Film Epintipg--Printing on plastic films, such as polyethylene and polypropylene, is generally re- served for rotogravure and flexography. The nonpabsorptive surface of the films is the main reason that these processes are usedpothe same reason they are used extensively for foil 6mm. Mn 12- 96- 7112i.- 8 IShifting Trends In Printingo-Part 2: Flexible Hate- rials,‘ op. cit., p. 118. 9:91 . 1°"Printers Guide For Alcoa Aluminum Foil,” (Aluminum Company of America, 1962), p. 2. 1&8 printing. Even though “for long runs on fine designs, gravure is desirable and can be economical,"11 flexogra- phy is "the most commonly used film-printing procedure."12 Plastic films, and most foils, are unique among printing substrates in that pre-treatment of the surface is necessary before any printing can.satisfaotorily be done. Foils are generally treated at the mill by coating the sur- face with an ink-receptive substance subsequent to the roll- ing Operation. In.contrast, surface treatment of plastic films (and plastic film-coated paper and paperboard) insolves a chemical change in the surface of the film, as the very property that makes film desirable for package barrier mate- rial-oits inertness~odoes not allow ink penetration.and ad- hesion. There are three basic methods of surface treatment ,of film: (1) chemical, (2) flame and (3) electronic dis- charge, and as one experimenter writes: Although there has beenhmuch work to determine the . . . changes which occur . . . as a result of surface treatment, the precise mechanism has not been defined. Among the theories . . . ad- vanced are: unsaturation of the surface mole« cules, surface oxidation, and molecular rear. rangement of the surface.13 110.8.1. Chemicals, §gipt;fifi 0n Polzolefin Film (New York: National Distil era a C emioa Corpora on, 1965)e P. 90 12gb1de. pa 8e 13Sherwood Leeds, “Surface Treatment of Polyethylene- C0.t0d Paper and Pap-rbOCIdgn 2222;, Vol. a“. NOe h (April, 1961). p. 24h. 1&9 The fact remains, however, that surface treatment does improve the printability of plastic films, and it must be used. The chemical surface treatment processes usually in, volve oxidation and/or chlorination by treating the film with a chromate, permanganate or other solution. As chem- ical treatments "are more costly, more difficult, and slower than physical treatments,”1h physical flame or electronic discharge methods are preferred. Flame treatment consists of passing the film on.a chilled roller past a gas burner. It is thought that this oxidizes the surface of the film. It is usually not in, corporated adjacent to the extrusion.prooess as the speed required for treatment is greater than.most commercial ex- trusion speeds. As a result, and because of high cost, corona, or electronic, discharge, is the preferred com- mercial method of surface treatment.15 Corona discharge treatment, in contrast to flame treatment, can be performed immediately following extru- sion. It consists of passing the film over a metal roller which is covered with a dielectric coating. The roller or drum is grounded and connected to an electrode, via a gene orator. As the film passes beneath the electrode, a corona discharge is emitted, thus ionizing the air into ozone which subsequently oxidizes the film surface. w.“ w—v 7w 1“U.s.1. Chemicals, cp. cit., p. 1. 15Ibid. pp. 2-3. CHAPTER XXVI DECORATING PLASTIC, GLASS AND METAL CONTAINERS Plastic Container Printing-~Semi-rigid and rigid plastic containers can take many forms as retail packages such as Jars, bottles, cups, boxes and squeeze bottles” Plastic materials such as acrylic, nylon, polyethylene, polyvinyl chloride, polystyrene and others are used to pro- duce these containers either by blow molding, injection molding or thermoforming. Decoration of plastic containers is usually accomplished by one or more of the following methods: (l)affset lithography, (2)screen process printing (3)any of the transfer processes and (h)any coating or in- pregnating process. As with plastic films, rigid and semi-rigid plastic containers also must be made ink-receptive following the molding process if they are to be printed directly with ink. In contrast to plastic films which are generally treated by corona discharge, most rigid plastic containers are flame treated and the ”chemical method is used for un- usual item designs which cannot be treated by the former methods."1 1 pa 5e “Printing and Decorating of Polyethylene," op. cit., 150 151 In general, surface treatment of plastic containers is required when they are to be printed by lithography, screen process, heat transfer and some types of hot roll leaf stamping. There are several decorating processes used which do not require treatment. Among these are pressure sensitive paper or foil labeling, embossing or raised surface, hot stamping, painting and dyeing. Plastic bottles and Jars are decorated directly on the substrate in almost any of the ways delineated above, and it would be impossible to Judge which process is used most extensively. Lithography and gravure-printed heat-transfer methods are used quite frequently, sapecially when halftone work and color process printing in quantity is desired. Screen process produces vivid colors and thick ink lay-down to increase lustre and contrast. Roll leaf and hot stamping are frequently used when.a luxurious, highpquality, expensive appearance is desired. Often spe- cial dies are incorporated into the mold which produces a raised effect on the container which can subsequently be inked with a rubber roller. Irregularly-shaped items are generally best decorated by painting, dyeing or by one of the newer inpth—mold trans- fer techniques. In addition, heat transfer processes have been adapted to print on irregular items of this type.2 2"Success In Printing Compound Curves," Modern Pegkgigfig V01. 39’ NO. 1 (September, 1965). pp. izg“ 152 Plastic squeeze tubes are commonly printed by screen process or offset, the latter process being the one most frequently employed.3 Metal Container Printing-~3etail metal containers are either metal cans or collapsible metal tubes. Both types of container can be either labeled with a paper label or printed directly on the metal. Hot processed food cans generally use paper labels, principly because of the verb satility afforded the processor. Lithographed cans, on the other hand, are used extensively for many nonpfood items, especially for "polishes, waxes and allied household items, frozen fruit Juices, beer and aerosols."u - Almost all printing on.aetal cans and collapsible metal tubes is offset lithography, while labels, of course, may be printed by any of the major printing processes. Collapsible metal tubes are printed on.special tube print- ing presses while they are still in the cylindrical fora of manufacture, before they are filled or crimped. The conventional three-piece metal can is printed with special inks on a regular offset press in.aultiple sheets, which are later cut into individual blanks, formed and sealed. 3Arthur N. Skeels, "Decorating Plastics Containers," gcdern Packaging Encyclopedia Issueo-126 , 02. cit., pp. 7 - 79+. “D. Bruce Wiesley, "Metal Cans,” Modern Packs 1 EncyclOpedia Issue-~1266, op. cit., p. 539. 5$pecia1 inks are required because of the heat used to process the printed blanks (320°? for 12 minutes), and to prevent cracking or chipping during the forming process. (From “Metal Decorating," Iechnical Develgpments In The Gra h10 Arts, OEe glte. p. 7 e 153 Extruded or drawn aluminum, or other two-piece cans are usually printed in the same general way as collapsible tubes, if they are not labeled. Glass Container Printing-«The majority of glass containers-obottles, Jars, etc.,--used today are either unprinted, screen process printed, labeled or contain re- lief images imposed during the molding process. Two pro. cesses, however, one relatively new and unexplored, and the other still in the experimental stage, are creating interest as a means of printing glass containers with I designs similar to those obtainable on cartons and other rigid packages. The first method-~applied coloro-is basically a screen process which uses specially-formulated glass inks. The ink is applied and then heated to 1010-1125 degrees Fahrenheit in special ovens where it is literally melted into the surface of the container. Colds, frosts, lustres, iridescents and crystal ice colors are among the wide va- riety of colors and effects obtainable.6 Electrostatic glass printing, as is most electrostatic printing, is still in the eXperimental stage of development. The process is quite similar to the applied color process except that electrostatic screen and toner (ink) principles are employed. The glass is heated to 1200 degrees Fahrenheit 6Anthony Velonis, "New Directions In Glass Decorating," Modern Packaging hncycloBedia Issue-~1966, cp. cit. pp. 3 '3 9- following application of the toner which fuses the toner 7 to the container. 7”Electrostatic Printing,” Modern Packaging, Vol.36, No. 12 (August, 1963), p. 202. APPENDIX I COURSE CONTENT APPENDIX I COURSE CONTENT For the most part, a course in packaging graphics designed from this dissertation should follow the same general subject matter sequence followed in the body of the paper. The material has been designed for use in.a three-credit, tenpweek quarter term, and as such, divides the content into 25 separate lectures leaving allowance for five class periods to be devoted to orientation, re- view and testing. This appendix is divided into two parts-~a course outline and a lecture schedule. The arrangement of the subject matter and the time allocated to each area of study is, of course, dependent upon the aims and purposes of the instructor. This appendix should merely serve as a guide or reference point for planning lectures. Course Out ine I. Introduction and orientation. A. Packaging graphics defined (Chapter I). 1. Definition of packaging graphics-«The study of packaging graphics, or packaging decora- tion, includes the study of all processes, methods and techniques, mechanical or other- vise, directly or indirectly necessary to prepare, create and evaluate the surface design of a package. 156 2. Be Th0 ins 1. 2. 3. b. II. Package 15? Objectives of the course. a. Not a complete study of all aspects of packaging graphics. b. General study of the packaging decorat- ing techniques with respect to history, the mechanics, preliminaries and pre- sent uses cf such as decorating media. c. Special emphasis on package printing. importance of packaging graphics as a aarket~ element (Chapter II). Increased use of packaging graphics as a mar- keting tool. General historical background of retailing and its effect on.packaging and packaging graphics. Factors contributing to the growth of packag- ing graphics in the supermarket. a. Increased self-service. b. Impulse or unplanned purchases. c. Greater number of products. d. Greater product differentiation. Packaging graphics must be a ”silent salesman". a. Present a good appearance. b. Identify the product. c. Illustrate the product. d. Gain initial attention. o. Create desire. f. Hold interest. g. Make sale. Decorating Processes. A. Introduction (Chapter III). 1. 2. Major divisions of package decorating techniques. ‘0 ”1111:1113. b. Transferring. c. Coating or impregnating. Functional classification of printing decorat- ing techniques. a. Pressing inks from a plateo—letterpress, offset, gravure, flexography. b. Pressing ink through a plateo-screen,pro- OCSSe c. Powdered ink and electrostatics--electro- static printing. B. Printing processes. 1. Pressure printing from plates. a. Letterpress printing (Chapter IV). 1) Oldest and most universally known pro- cess. 2) Early Oriental background. 3) "Father of Modern Printing”-~Johann Gutenberg (Germany, thO's)-first printed book from movable type, the Gutenbegg Bible. 158 u) Printing spreads to England and the Colonies. a) Caxton (England, lh70's)--§;§¢ arise at Tram» b) Stephen and Matthew Days (0.8., 1683)--Baz Psalm Book. 5) Subsequent typemaking and press develop- ments. a) Blaeu (l620)-—rolling bed of type. b) Ged (l725)-metal stereotypes. o) Earl of Stanhcpe (l800)~oall-metal press. d) Konig (lBOh) and Hoe (18h6)-rotary presses. 6) Recent advances. a) Improved versatility; platemaking; higher speeds and.web-fed, ineline die-cutting and creasing. 7) Description and operation of the basic letterpress system. 8) Letterpress presses. a) Platen. b) Flat-bed cylinder. c) Rotary. Flexographic printing (Chapter V). l) Letterpress printing from rubber plates. 2) Early history and develcpment. a) Bibby, Baron & Sons (England, 1890) c-Rotary rubber plate letterpress for paper bags. b) Holweg (l908)-aFirst true aniline press. c) Two decades of crude printing and little develOpment. d) Concurrent rise of flexcgraphy and flexible packaging materials during the 1920's and 1930's. e) PI's adoption of the name flexography as a "method of rotary letterpress printing which employs flexible rub- ber plates and rapid drying fluid inks.” 3) Description.and Operation of the basic flexographic press. Offset Lithographic printing (Chapter VI). 1) Planographic, oil-water printing. 2) Discovery of lithographic printing- Senefelder (Germany, 1790's). 3) Used as a fine art medium until 1820- 1830 when first used commercially. u) Technical developments. a) Eugues (France, 1850)--steam driven press. 2. 3. d. 159 b) Poiteven (France, 1855)-Photogra- phic platemaking. 0) Thin, flexible plates and rotary presses-~(1889). c) Offset press-~Barolay (England, 1875) and Rubel (U.S., igou). 5) Use of sheet-fed offset; web-fed, ro- tary offset and direct lithe presses. 6) Description.and operation of the basic sheet-fed rotary offset press. Rotogravure printing (Chapter VII). 1) New (since 1930's) method. 2) Early developments. a) Bell (Scotland, l783)-textile print- ing from intaglio wax-coated cylinn ders e b) Niepce (France, 181”) and Talbot (France, 1852)-photographic gravure platemaking. c) Klic (1897)-earbo .tiesue etching-- "Father of Modern Rcto vure". d) Storey Co. (England, 1 93-1895)- First commercial uses. e) Adapted for newspaper printing.- f) Later developments in inks, color control, platemaking techniques and highpspeed presses. g) The terms rotogravure and gravure. )Description and operation of the basic rotogravure press. Contact printing through plates-oscreen.pro- cess printing (Chapter VIII). 3e b. Silk screen, stencilling, serigraphy, mito- graphy and soreen.prooees defined. 1) Serigraphy developedaowPA Project (1938) oofine art medium. 2) hitcgraphy coined-«Kosloff (l9h5)-- screen process. History and development. 1) Early stencilling. 2) Simon (England, l90?)-~use of silk flore on. 3) Pilsworth (U.S., l9lh—l9lB)-Se1ecta~ sine color process. 3) Recent photographic screen.naking, half- tones, nonpsilk screens and faster presses. Description and operation of screen.pro- cess presses. Pressureless printing-Electrostatic prinming (Chapter IX) 0 One of the newest techniques. h. 160 b. History and related developments. 1) Scott (U.S., l930)-pouder puff print- ing. , 2) Basmussen.(Dennark, 1930's)-Corona discharge spray. 3) Carlson (U.S., l9hZ)-Photoconductive plate and screen. h) Shaffert and Battelle Memorial Inst. (0.8., l9flfi, 1946, l950)~-Xerography, xercprinting and Xerox copiers. 5) Goss Printing Press Co. (England, 19h8) and Shaffer (U.S., l951)-E1ectrostatic transfer of fluid ink. 6) 531 (UeSe. 1960.8)..EePeCe PTOOOIIe c. Description and operation of electrostatic presses. Hybrid printing processes (Chapter x). a. Dry offset (letterset) (1919). b. Wrap-around letterpress. c. Xographic printing (3-D) (1964). C. Transfer processes (Chapter XI). 1. 2. 3. k. 5. Hot stamping and hot roll leaf stamping." a. History, and roll leaf development. b. Hot stamping process and presses. Decalcomania. Heat transfer printing. a. Hot stampndecalcomania hybrid. b. Developed by Dennison.(l955) as Therisage. c. Therimage equipment. L‘b011n8e a. Types of labels and adhesives. b. Labeling equipment. Hybrid transfer processes (Chapter XII). a. Electronic transfer decalconania. b. Hulti-oolor heat transfer. c. Inwthe-mold transfer. D. Coating or impregnating processes (Chapter XIII). 1. 2. Painting. D101n8e III. Original art and platemaking. A. Preparation and care of original copy (Chapter XIV). 1. Types of package copy. a. Line ccpy. 1) Lines, dots solid areas-«no tonal gra- dation. 2) Pen or brush and ink, scratchboard, lettering, type proofs, graphs and charts, etc. 3) Preparation of line ccpy. a) Paper and ink requirements. b) Line and shading angle requirements. c) Type proofs and typewritten ccpy re- quirements. B. C. b. 0. 161 h) Cold type composition. a) Photographic (photocomposition)-- Fotosetter, Photon, Linofiln, etc. b) Nonpphotographic-oArtype, Craftype, Presstype, etc. Halftone ccpy. 1) Photographs, prints, sketches, paint- ings, etc. 2) Types of halftones. a) Square. b) Silhouette. c) Highlight. d) Vignette. e) Combination. Color copy (discussed in Chapter XXI). 2. Care and handling of original copy. Introduction to photomechanical platemaking (Chapter XV). 1. Definition of photomechanics. 2. The general photomechanical platemaking process. Platemaking for letterpress and flexography (Chapter XVI). 1. Definition of, and basic steps in producing, photoengravings. 2. Line and halftone photoengraving. Ce b. 0e d. 0e f. 8e Photographing the copy. The halftone screen. Stripping negatives onto the flat. Erposure in a vacuum frame. Deve10ping, drying and heating the plate. Etching. 1) Line photoengraving etching. 2) Halftone photoengraving etching. 3) One-bite etching. h) Electronic etching. Routing, planing and finishing. 3. Duplicate plates. fie b. 0e d. Electrotypes. Stereotypes. Plastic plates. Flexographic rubber plates. 1) Holding process. 2) Types of plates. a) Plainbaok. b) Stickyback. c) Pro-curved. d) Bras 8-mck e Wrap-around letterpress and letterset plates. 1) Dycril plates. 2) Kodak Relief plates. D. E. F. 162 Platemaking for offset lithography (Chapter XVII). l. Offset plates. a. Surface plates. b. Deep-etch plates. c. Multi-metal plates. 2. Step and repeat photocomposing. Platemaking for rotogravure (Chapter XVIII). l. Rotogravure vs. offset or letterpress plate- making. 2. Types of plates. a. Conventional gravure plates. b. Lateral hard dot or half tone gravure plates. Platemaking for screen.process (Chapter XIV). 1. Net carbon tissue. 2. Dry carbon tissue. 3. Ektagraph film. b. DuPont film. 6. Clone Fate-film. 7. Active micro photo film. 8. Polyvinyl alcohol direct. 9. Birtex direct. IV. Color printing. A. B. Color theory, matching and measurement (ChapterXX). 1. Light, pigment and color. a. Newton (l666)-prismatio separation of light into colors. b. Electromagnetic nature of color. c. Pigment nature of color. d. Dual nature of color-1ight and pigment. 2. Color identification. a. Physical systems. 1) Ostwald system. 2) Color Harmony Manual. b. Subjective systems—~Munsell color system. 1) H‘lBe 2) Value. 3) Chroma. 3. Color matching. a. Importance. b. Metamericism. c. Color matching inks. a. Color measurement. a. Photoelectric calorimeter measurement. b. SpectroPhotomer. Color process platemaking and printing (Chapter XXI). 1. Basic principles-ooolor separation. 2. Color platemaking. a. Copy preparation. b. Color separation negatives. 0. Color correction. 163 d. Color halftone negatives. l) Photographing separation.negatives through halftone screen. 2) Screen angles. e. Photoprinting and etching. 3. Color printing presses. a. In»line-rotogravure and offset. b. Stack-uflexography and offset. 0. Central impression cylinder-~1etterpress, offset, flexography. C. Printing inks (Chapter XXII). 1. Importance. 2. Composition and functions. a. Vehicles. 1) Absorption drying. 2) Oxidation drying. 3) Evaporation drying. 4) Othersa-wax-set, moisture-set, quick- setting, cold-set. b. Pigments. l) Black-~carbon, furnace, lamp and mineral. 2) white-0paque and transparent. 3) Inorganic color-onatural minerals. u) Organic color-~synthetic chemical com- pounds. c. Miscellaneous components. 1) Driers, as drying catalysts. 2) Waxes, to prevent sticking. ) Greases, to reduce tack and to lubricate. ) Solvents and thinners, gums, antioxidants, corn starch and surface active agents. 3. Inks for paper. h. CellOphane, plastics and metal inks. 5. Letterpress, offset, rotogravure and screen process inks. V. Decorating packaging materials. A. Introduction (Chapter XXIII). 1. Variables. a. Economics. be Quality. 0. Substrates. B. Paperboard and corrugated containers (Chapter XXIV). 1. Folding cartons. a. Letterpress (31.7 percent). 1) Most on sheet-fed, flat-bed presses. 2) Increasing amounts by wrap—around and letterset because of makeready time and plate economics. b. Offset (23.? percent). 1) Increasingly more use at expense of letterpress-cost ofplates and higher quality reproduction. 2. 16h c. Flexography (18.6 percent). 1) Wax and plastic coated milk containers. 2) Beverage carriers. 6. Gravure (2h.1 percent). 1) Fastest growing-oweb-fed cutting and creasing since l9h0's. 2) High Speed, long cylinder life, quality color and halftone. e. Combination of methods. Corrugated containers. a. Letterpress-omajority of containers- ~ rubber plates, but not flexography. b. Flexography--growing with new ink and press deveIOpments. c. Rotogravure and offsetn-high quality,long run pro-printed liners. 6. Screen process-olimitedo-brilliant, in- tense colors~~pcint of purchase displays. C. Flexible packaging materials (Chapter XXV). l. 2. h. Paper wraps, bags and labels. a. Bags. 1) Historically letterpress. 2) Flexography since 1900's. b. Wraps. l) Historically letterpresso-still used for bread wraps. 2) Most by gravure--Speed, quality and variable cylinder circumference. 0e Labels. 1) Historically letterpress. 2) Host lithography-quality, speed, step and repeat, and gang runs. Collaphane. a. Gravure for quality, halftone and color, and quantity. b. Flexography for short runs, many copy changes. F011e a. Ninety percent by gravure, some flexography. b. Some sheet-fed offset and letterpress for short runs. Plastic films. a. Flexography, some gravure. b. Surface treatment required to improve printability. l) Flame-r-EXpensive, involves extra pro- cessing. 2) Corona dischargeo-preferred. 3) Chemical-Expensive, hazardous, used very little. D. 165 Plastic, glass and metal containers (Chapter XXVI). 1. Plastic containers. &e be 0e do Be f. Surface treatment (usually flame) neces- sary. Lithographyo-quality and halftones. Heat transfern-quality and halftones. Screen process-~vivid color. Roll leaf and hot stamping-~luxury look. Painting and dyeingu-irregular, specialty tOmBe 2. Metal containers (cans and tubes). 8e be Labels-cprocesses food cans, some tubes. Lithography on other cans-speoial inks and presses. 3. Glass containers. a. b. Unprinted, screen process, labeled or reliefed. New processes. 1) Applied color-oglass inks fused to cone tainer. 2) Electrostatic-nfused to container. 166 Lecture Schedule Lecture Number Course Outline Subject Matte; 1 IeAe 2 I.B. 3 IIeAe b II.B.l.a. 5 IIeBelebe 6 IIeBeleOe 7 IIeBeleOe 8 II.B.2. 9 IIoB.3. 10 II.B. . 11 IIeCele. IIeCeZe and IIeCeae 12 II.C.hoand IIeCeSe 13 II.D. 1n III.A. 15 IIIeBe, III.C.l.and IIIeCeZe 16 111.0.3. 17 IIIoD. 18 III-E. 19 IIIoF. 20- IV.A. 21 IV-B. 22 IV.C. 23 VeAe ‘nd VeBe 2h VeCele. VeCeZe and VeCeBe 25 VeCehe and VeDe APPENDIX II SUGGESTED LABORATORY EXERCISES APPENDIX II SUGGESTED LABORATORY EXERCISES Laboratory exercises for a course in packaging graphics should serve to supplement the material taught in the course lectures. They should provide the student with concrete examples of the printing and decorating processes, how to identify them, how to test various prop- erties of ink and substrates as related to printing, how to prepare ccpy for printing reproduction and how to eval- uate the graphics on a finished package. This appendix contains five groups of selected laboratory exercises which could be applied to a begin, ning course in packaging graphics. No attempt is made to outline detailed testing and evaluation procedures as they are dependent upon the individual objectives of the instructor, the time allocated, and the materials and equipment available. The following groups of exercises are suggested: (1) copy preparation techniques, (2) ink and substrate tests, (3) color matching and identification, (k) identification of printing methods and (5) evaluation of finished graphics. 168 169 Copy Pgeparaticn.Techniques-osn exercise in.oopy preparation techniques should acquaint the student with the techniques and materials used to produce ccpy for pack- age printing, and with the various types of line, halftone and color copy. It should include such exercises as mark- ing photographs or drawings to fit a specific size re- quired, the use of paste-down or press-down cold type and type proofs, the use of color overlays and the production of the final layout. The student could easily create a simple three- or four-color line engraving layout, complete with tissue overlays and line ccpy. Ink and Substrategggggge-These exercises should include various testing methods concerning the physical properties of ink, ink adhesion preperties and printabilc ity of various substrates, especially plastic films. Among the tests included should be: 1. Ink adhesion.testg, such as the thumb nail scratch tes , crinkle test and pressure- sensitive tape test. These are all subjec- tive test methods. A more quantitative ad- - hesion.test can be performed on.a tensile tester by "gluing" two substrates together with ink and performing a peel test. 2. Blockigg and blockigg resistagge tests, cone 3 st ng o pressing two on strates together and evaluating the difficulty of separation, can be performed between printed and un» printed surfaces, between printed surfaces, and under various conditions of temperature, pressure, humidity and time. 3. Chemical resistance tests, such as water resistance, alkali resistance, oil resist- ance and grease resistance tests. These can be performed on a printed or unprinted substrate. 170 h. Printability tests to determine the surface treatment adequacy of substrates (particu- larly plastics) such as tape tests, wet- ability tests, peel tests and dye-stain tests. Color Matching and Identificationp-Thesc exercises should acquaint the student with the methods of determine ing whether or not an ink or printed sample is preperly color matched, with effects of various lighting and illumi- nation, with metameric matches, and with color composition. A Color difference meter can be used to determine the color composition of a printed sample. Also, a device which spins color chips in various amounts can be used for the same purpose. Both of these could be supplemented with a color system such as the Cole; garmonz Manual. Light comparison boxes, which contain different il- lumination sources could be used to show effects on color of different illumination. Illumination.devices used to detect metameric matches can also be utilized. gdentification of Printing Methodso-Substrates containing various methods of printing can be examined by the student under a microscOpe or other magnifying device in order to determine the method of printing or decoration. Samples which require additional evaluation such as the type of material printed on should also be included. Also, the student should be able to identify specific types of ccpy printing such as line copy, single and multi- color halftone ccpy, and various types of halftone screens used. A student could be required to compile a notebook 171 containing specimens of the various types of printing and decorating techniques. Evaluation of Finished Graphiggy-The purpose of these exercises should be to acquaint the student with various methods of determining the legibility, readability, etc., of finished graphic designs. Various instruments such as the polariscOpe, angle meter, shadow box, blur meter and tachistasoOpe could be utilized. Variations in type, composition, size, color, and lighting could be ins vestigated. BIBLIOGRAPHY BIBLIOGRAPHY BOOKS Biegleleisen, J.I. and Max Arthur Cohn. Silk Screen Tech- nigues. New York: Dover Publications Inc., I953. Carr, Francis. A Guide to Sgneen Process Printing, ed. Brian Innes and Beatrice Wards. New York: Pitman Publishing Corporation, 1962. Cartwright, H.H. and Robert MacKay. Boto ravure: A Survgz of Euro can and American Methods. Lgfidcn, Kentucky: MacKay Publishing Company, Inc., 1956. Flerographic Technical Association, Inc. Flero ra hm: Princi les and Practices. New York: Flexograph! Technical Association, Inc., 1962. Pladager, Vernon. The Selling Powen of Packaging. New York: McGraw-Hi Book Company, Inc., 95 . Hymes, David. Production in Advertising and the Granhic Arts. New York: Ho t, R ne an Wins on, c., 958. Kcsloff, Albert. hitcgranhz: The Art and Craft of Screen Process Printi . hilwaukee: The Bruce Pub shing Company, I952. . ghetOgranhic Screen Process Printing. Cincinnati, Ohio: The Signs 0 t e Times Pub sh ng Company, 1955. Latimer, H.C. Surve of Litho ra h . New York: Lithographic Technical Foun t on, Inc., 95“. Long, Robert P. Packnge Printing. Garden City, New York: Graphic Magazines, no., 9 u. McCarthy, E. Jerome. Basic Marketi : A Ma erial A roach. Homewood, Illinois: Richard D. Irvin, Inc., I960. 5 173 17:. PERIODICALS ”Corrugated Printing Progress Report," Consumer geckaging, (December, 1960), pp. 5h—57. "Decorating Molded Plastics,” Modern Plastics Enc lo edia Issue-~1265. New York: McGraw-Hiil, Inc., 1965, pp. 7 7 . "Electrostatic Bows In," Modern Packaging, Vol. 38, No. 1 (September, 1964), p. 255. "Electrostatic Printing,“ Modern Packagnng, Vol. 36, No. 12 (AWSt. 1963, De 202s "Electrostatic Printing,“ Pagerbcard Packaging, Vol. 50, N00 5 (KEY: 1965): PP. 5+0 "Electrostatic Printing In Use," .odern Pack 1 , Vol. 36, No. 11 (July, 1963), p. 103. “Flexo Printing Outlook: Bright,“ Panerboard Packaggng‘ VOle “9. NOe 7 (July, 196“). pp. 8+e 7 Geiger, Robert J. and Arthur R. Johnson. “Labeling Machinery," Modern Packaging Encyclonedia Issue! 1266. New York: McGraW—Hill, Inc., 9 . pp. 5 ¢ e Goat, Arthur F. “Cartons By Gravure,” Gravure, November, 1963 reprint. “Heat Transfer Printing," Modern Packs 1 , Vol. 3h, No. 1 (September, 1960), pp. 1253155. Hochncr, Walter L. “Molded~ln Foils," Modern Plastics Enc - clogedia gssuecolg65. New York: McGraw-Hill, Inc., 9 : PP. 7 ’7 4+0 Leeds, Sherwood. "Surface Treatment of Polyethylene-Coated Paper and Paperboard," 2nnni,‘Vol. 49, No. b, (April, 1961). pp. 244.250. MacKay, Robert. "The Remarkable Growth of Rotogravure," Paner, £11m and Foil Converter, December, 1956, (Series of Reprints . "Packaging Pacemakers: Eastman Kodak,“ Modern Packnging, V01. 39! N00 7 (March, 1966). pp. 120- 3+0 175 ”Painting Plastics, ' Modern lest cs Enc clc ed a sous-o 1265. New York: heGraw-Hill, Inc., 1965, pp. é53:757. ”Plus In Nulti-Colcr Printing,“ Hodegn Packaging, Vol. 38, NOe 2 (OOtObOT. 196“), pp. 0-1 +e Senchagrin, Ted. "The New Power of Packaging: Management Takes Control,“ n er's nk, Vol. 290, No. 12 (June 11, 1965), pp. - +. Sherring, Fred. "CCC Plant Praises Lettereet With Dycril Plates,“ generboard zacnnging, Vol. #9, No. b (April, 196“): PP. 7 ’7 0 "Shifting Trends In Printing-oPert 2: Flexible Materials," nodern gscgnggng, Vol. 35, No. 1 (September, 1961), pp. . e Skeels, Arthur N. "Decorating Plastics Containers," 1 66. New York: Smith, Daniel. "Electrostatic Printing," godgrn Encgnging, Vol. 36. NOe 5 (January, 1963). pp. 11 e "Success In Printing Compound Curves ” nodefn gscknging, Vol. 39, No. 1 (September, 1965), pp. - 7. "The True Look/1963," Suner hanks; Merchandisgng, Vol. 29, NO. 7 (July. 1966‘ e "The True Look of the Supermarket Industry, 1969," Su er arket Merchand s , Vol. 30, No. b (April, 19 5 , ppo £9-72. Tuttle, Douglas E. and D.C. Holland. "Aniline Printing-I," odern Packs 1 , Vol. 23, No. 10 (June, 1950), pp. £85.”)? T“. ""5"!!! Velcnis, Anthony. ”New Directions In Glass Decorating," Modern gacnnging Encgclonedia issue51266. New York: NoGraW-H , nc., 5, pp. - . Waughtel, Kenneth. "The Eastman Kodak Relief Plate," s er- ham Backgm, V01. 50. N00 5 (May, 1965). ppe3 So ”What You Should Know About Pack e Printing,” Modern geck- nging Encgclonedia Issuec-lg . New York: NcGraw-Hi 1, Inc-. 9 9 PD. 55" 5 ' Wiesley, Bruce. "Metal Cans," Modern Packs i Enc clc edia ssue--l 66. New York: NcGraw-RIII, Inc., 196%, pp. 653-359- 176 wortman, Charles. "A Comparison of wrap-Around Letterpress and Letterset (Dry Offset) Printing For Folding Garb tons," Pa erboard Pack 1 , Vol. 50, No. 5 (May, 1965). pp- 31-35- PAMPHLETS, BOOKLETS AND MANUFACTURER'S LITERATURE "The Art of Photoengraving," American Photoengravers Association, 1952. ”Basic Requirements For Better Electrotypes,' Cleveland, Ohio: International Association of Electrotypers and Stereotypers, Inc., 1957. "The Electrotype and Stereotype Handbook," Cleveland, Ohio: International Association of Electrotypers and Stereo- typers, Ince. 1952s ' ‘ 'Flexographic Printing, Where Does It Stand? What's Ahead?,' Technical Developments In The Granhic Arts. New York: Lithographers and Photoengravers Inter- national Union, 1965. Gravure Technical Association. Rotogravure Ink. New York: Gravure Technical Association, 1963. "A Guide to Foil Stamping," Hartford, Connecticut: M. Swift & Sons, Inc., 1965. Intaglio Service Corp. ”Gravure,” New York: di Russo and Falborn, Inc. "Line, Halftone and Color," American Photoengravers Associ- ation, 1959. McCray, Elwin E. "Graphic Arts For Journalism: An Intro- duction," second edition: East Lansing, Michigan: Michigan State University Press, 196“. (Nimeographed). McFarlane, Samuel B., Jr. ”Electrostatic Printing," a paper presented at the Fourteenth Technical Confer- ence of the National Printing Ink Research Institute, Lehigh Undversity, Bethlehem, Pennsylvania, September 18, 1962. New York: Sun Chemical Corporation, 1962. "Metal Decorating,” Technical Developments In Inc Graphic Arts. New York: L thographers an Pho oengravers International Union, 1965. 177 Pegaz, David. 'Photomechanics and Printing in Package Production," unpublished academic paper, School of Packaging, Michigan State University, 1965. Pocket Pal. eighth edition: New York: International Paper Company, 1969. "Printers Guide For Alcoa Aluminum Foil,“ Aluminum Company of America, 1962. "Printing and Decorating of Polyethylene," Clifton, New Jegeey: w.a. Grace & Co., Polymer Chemicals Division, 19 1. ”Printing Ink Handbook," New York: National Association of Printing Ink Makers, Inc., 1958. The Research Association of British Paint, Colour and Var~ nish Manufacturers. Color In Surface Coatings. Ted- dington, Middlesex, England: Paint Research Station, 195 . Staehle, Henry C. "The Kodak Relief Plate,“ Technical Develonments In The Granhic Arts. New York: Litho- graphers a Photoengravers International Union, 1965. Stevens, William J. and John A. McKinyen, now To Prepare Art and Copy Ear Offset LithOgranhy. Maywoo , New Jersey: Dorva Pu sh ng Company, 19h8. "Supermarket Buying Decisions in the U.S.," The 2th DuPont Consumers Bu 1 Habits Stud . Wilmington, De aware: E.I. DuPont is Nemours and Co., Inc., Film Depart- mant , 1965 e U.S.I. Chemicals, Printi On Pol olefin Film. New York: National DistiIIers and ChemicaI Corporation, 1965. Weiner, Leonard A. An Introduction to Color and Meagnne- ment. Nutley, New Jersey: At antic Chemical Corpora- tion. 1965. "wrap-around Letterpress: A Growing Acceptance," Technical Develonments In The Granhic Arts. New York: Litho- grzphers and Photoengravers International Union, 19 5. HICHIGRN STRTE UNIV. LIBRQRIES 31293101407843