A STUDY OF THE LAUNDERAELITY OF SHEETS flwaasis fa? +53 Dagme :3?! M. S. {WCHIGAN SzATE CORLEGE Ruirh Marion Garcia Broflan 1*?«3 ‘ej HFSiS has been accepted towards fulfillment of the requirements for _ . “Ma“ M'$ degreein WM MSU LIBRARIES RETURNING MATERIALS: PIace in booF drop to remove this checkout from your record. FINES w111 be charged if book is returned after the date stamped below. “n—__.-_-. _ ’73 .A STUDY OF THE LAUNDERABILITY OF SHEETS A. Comparison of the Launderability of three grades of Sheets. B. Comparison of the Methods of two Institution laundries 0 BY Ruth Marion Gerda ngtten A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department or Institution Administration 19h8 2mm M “*3 .ACKNOWLEDGMENT The writer wishes to express her appreciation and thanks to all who assisted in.making this study possible: particularly to Professors Mabelle S. Ehlers and Hazel B. Strahan under whose supervision this work was done; to Dean maria Dye for her suggestive criti- cimm. Thanks are also due to the American Institute or Laundering for its cooperation in making the white- ness retention readings; to the Alley Linen Supply 00., J. C. Penney 00., Mr. Nicholls of Knapp's Department Store, and Mrs. Louise Carpenter for their contributions or the sheets used in the study; to Mr. Reynolds who supervised the laundering or the sheets at the Ingham County Sanatorium, and to Miss Gertrude Mueller who supervised the laundering at the Michigan State College Laundry; also to Mr. Jake Fasset, Director or the Service Department, American Hotel.Association, for his cooperation. I. II. III. IV. V. VI. VII. VIII. TABLE OF CONTENTS Introduction Review of Literature Methods of Procedure A. Organization of the study B. Laundering Procedures 0. Laboratory Tests 1. Physical characteristics before laundering. 2. Physical characteristics after laundering. Discussion of Findings Conclusion Summary Literature Cited Appendix Page 11+ 31 #5 L9 51 53 INTRODUCTION 0f great concern to the institution manager is the life expectancy of institution equipment and furn- ishings. Careful consideration.must be given to the purchasing and care of institution furnishings that will best serve their purpose for the longest period of time. Table linens and bed linens because of constant wear and laundering make necessary mere frequent replacement than items of a more durable character. Comprehensive studies have been made by manufacturers, governmental, and other agencies on the qualities of sheets resulting in criteria for intelligent selection. Most of these studies, how- ever, have been of.more value to the homemaker than to the institution buyer. Linens are given more constant wear as well as different and more frequent laundering in institutions than in homes. It is logical then that studies of the comparative serviceability under normal conditions of use and care in institutions would be help- ful to the institution buyer. a. A. Boss,2 head of the Boss Hotels System, says that no salesman seams to know how many times an ordinary hotel sheet can be laundered under usual hotel conditions, nor does he know how many times a peroale sheet will launder in comparison. In selecting sheets, the homemaker is interested in the following factors: price, size, type, balance in yarn count, tensile strength, the salvage, width of the heme, and the 'finish” of the fabric. An institution buyer considers these same factors of serviceability and particularly considers the weight of the sheets which from the standpoint of laundering is a significant factor. The type of clientele which a hotel serves is also a de- termining factor in the selection of sheets of fine quality for hotel use as contrasted with the kinds of institutions. Hams of uniform width at the top and bottom.are an economy because either and may be used at the top, thus distribut- ing the wear more evenly, and saving time since it is un- necessary for the maids to look for the top or bottom of the sheet when making up the beds. Because hotel and hospital bed linen is changed so often, it contains very little soil, and so does not require a strong washing solution. It needs little or no bleach and.very little agitation in order to wash it clean and make it thoroughly sanitary, according to George Edwards,5 maintenance Consultant to the American Hotel .Association. He also stated that the length of service that linen gives cannot be computed in terms of weeks or months but in terms of the number of washings that it re- ceives and the character of the washing. The life span of linen usefulness in a hotel or other institution depends entirely upon: (1) the quality of the linen, and (2) the type of laundry treatment which it receives. tMany institutions operate their own launderies where the washing process can be controlled to suit their needs; others must send their linens out to commercial laundries where they are washed with all types of linen and all types of soil and where the washing formula may be set to remove soil with a maximum.of pounding action and often with a strong bleach. It seems desirable then, not only to have more technical data on the initial characteristics and per- formance values of sheets in constant service, but also how well they will withstand the laundry process and how they are affected by it. This may determine whether or not the laundry process is the best that can be used in order to give the sheet longer life. This investigation was undertaken (l) to com- pare three types of sheets commonly used in institutions, and (2) to compare the washing procedures of the Michigan State College Laundry with another type of institution laundry. ‘ REVIEW OF LITERATURE Since the study is divided into two parts, the first, that of determining the types of sheets which are best suited for institution use, and the other, to com- pare the washing procedures of two types of institution laundries, the literature reviewed will also be divided into two parts. The first part will deal with studies that have been.made on sheets and buying guides and the second on laundry processes. Most of the studies that have been made on sheets have been undertaken primarily for the purpose of pro- viding information for the homemaker. While institution buyers are also interested in many of the factors which influence the homemaker's choice, their criteria for ‘ selection is necessarily different. N. G. Bennettl in a research study at the Uni- versity of Missouri, on a comparison of qualities and prices of sheets available ianissouri stores states that the main problems confronting the consumer are: 1. How to determine and recognize desirable qualities. 2. What weight and kind of material to purchase in order to obtain maximum durability. 3. What type of sheet will be most economical to buy. -5- She goes on to say that the aids for the consumer in Judging the quality of sheets are inspection, price, past experience, brands or trademarks, labels and laboratory testing. Labels are becoming increasingly important and more informative. Many companies label their products, stating thread count, percent of sizing, tensile 1“ study at strengflh, and size. In Barbara‘webster's Pennsylvania State College of a contribution to the de- velopment of a performance test for sheets, she concluded that labeling based on the performance of a sheet after repeated launderings would be of more value to the con- sumer than labels based on initial characteristics. 8, in a government study of the M. B. Hayes classification of sheets as an aid to consumer buying, suggested the following minimum.specifications for five classes: , Thread Count Breaking ‘Weight in Warp Filling Strength Ounces per __g (grab)* Square Yard Percale 100 96 I 60 3.8 max. Fine Count 86 82 60 3.7-h.0 Heavyweight 7h 66 70 h.6 min. Mediumweight 7O 60 50 4.2 Lightweight 60 52 to 3.7 *h Specimen four inches wide and six inches long is required for this test. The Office of Price Administration, an agency set up during World War II, is responsible for mandatory labeling regulations on bed linens which are sold across retail counters. Under this law sheets are classified according to four types rather than by name as in the study done by Hayes. A comparison of the minimum requirements as is shown in the 0.P.A. table shows that type 180 falls between the parcels and fine count sheets in the Hayes table, type 140 and heavyweight are the same, type 128 is comparable to mediumweight; and while type 112 and lightweight are the same. This table 18 on page 7- V. G. Slutz,12 at the University of Tennessee, made a study on the relationship of the physical char- acteristics of fibers found in wide bleached cotton shooting to the durability of the fabrics as determined by laboratory tests and found that there was a tendency for sheeting to have more yarns per inch in.the warp than in the filling, but that there was not a great deal of difference between the yarn number of the warp and the yarn number of the filling yarns. The shrink- age in the warp was greater than in the filling, and the warp yarns were stronger than the filling yarns, both in the dry and in the wet condition. A greater number of investigations like these have been made for home use, but some experiments have Egbeling Rule on Sheets *1 *2 *3 Type 180 Type 149 Type 128 Type 112 Yarn Count per square inch 180 140 128 112 Weight per sq.yd. (ounces) 3.6 h.6 h.0 3.7 Tensile strength (grab) (pounds) warp 6O 70 55 #5 Iilling 6O 70 55 #5 Selvage Tape Tape .Tape Tape Plain heme h-S- (total for both ends) h” h. h” h” Stitches por inch 11. 11. 11. 1:. *h *5 Added sizing (max.) A% h% 6% 10% *1 This table states minimum specifications (except) for added sizing) for each type. *2 In the event of failure to meet minimum.specifications for any given type as set forth in Table I, the goods shall be deemed to substandard and the applicable maximum price shall be deterfiined pursuant to sub- paragraph (3) of paragraph (d). *3 Bed linens having a finished thread count of less than 175 shall not be classified as Type 180 re- gardless of whether they meet all other speci- fications of that type. *A & *5 Not applicable to brown sheeting. been carried on in institutions. .A two year test on hotel sheets conducted by Bossz, in his hotels, was done to find which sheet would be the most economical for hotel use and at the same time provide a satisfactory sheet for the guest. Results showed that the sheets con- siderably lighter in weight than muslin sheets but higher in thread count stood up under more than 300 periods of actual service and 300 washes in normal hotel use. The initial cost of these sheets was higher, but the greater original cost was offset by the reduced cost of laundering over the lifetime of the sheet, because of its lighter weight and its relatively small loss in weight after con— tinued periods of service and washings. He does not state that this sheet is percale, but the assumption is clear. In Edward's6 study he found that sheets washed after each night of service lost only h0% of their strength after 125 washings. They were washed 170 times before any breaking of the fabric was noted and 200 times before they were worn out. Hays and Rogersg, in the Division of Textiles and Clothing, U. S. Bureau of Home Economics, concluded from their study on four classes of sheets during service, that one period of home wear was not equal to seven days of hotel wear, but was more nearly equal to three days of hotel wear. One period of home wear is regarded as equal to one week's use plus laundering, and seven of hotel use equal to seven night's wear and seven launder- ings. They found that the amount of service given by a sheet is closely related to its filling breaking strength. According to these investigations, the medium weight muslin sheet was found to give the least service, while the heavy weight.muslin gave the best service. Laundering is a cleansing treatment which has to be repeated frequently during the life of an article. Articles to be laundered must be classified: (1) as to material of which they are made, (2) as to type of article, and (3) as to the amount of soil. Each classi- fication needs special treatment. R. E. V. Hampson7, Director of the British Launderers' Research Association states, in his article on the effects of laundering processes on fabrics, that there are three features to Observe for good washing: (1) the ability to detach dirt from the fabric, (2) the ability to suspend the dirt detached and prevent its redeposition, and (3) adequate means of removal of liquid from the machine in which the operation is per- formed. He says that the launderability of a fabric is its suitability for the whole process of laundering, as carried out by recognized and preper methods. The stages in the washing process and the pur- pose of each are also described by Hampeon. The first water in the laundry process is known -10- as the ”break” of "breakdown" -- the temperature of the water is about 90-1000F., no soap is added, and very little mechanical agitation is given the washing load. The purpose of the “break" is to thoroughly wet the load, and to remove the large particles of dirt. The first suds follows, and in this stage a large portion of the soil is easily removed. The temp- erature of the water is between llO-lZOoF., and a soap is used. The second suds removes the soil which is more difficult to remove. The temperature is increased to lAOOF., a soap is used, and more agitation is given the clothes. The purpose of the third suds, when it is used, is to remove the more resistant soil. The temperature is increased, also the mechanical action. Several rinses follow the sudsing Operations. These remove the soap from the articles being washed. Laundry chemicals are used in the washing pro- cedure, all with the intention of making the articles white, and as near to their original color as possible. The clothes may be subjected to a chlorine bleach, by the addition of a dilute solution of sodium hypochlorite in the washing machine. B. Levitt11 in his article on laundry chemicals says the most economical method is to make it from caustic soda and chlorine: 2NaOH & Cl2 -- -11- NaOCl & NaCl & H20. The chemical reaction.that takes place when chlorine bleaches is as follows: sodium hypochlorite being an unstable chemical when introduced into a hot solution quickly decomposes to liberate nas- cent oxygen and sodium chloride. The active oxygen bleaches and disinfects. Laundry blueing may be used alone or in com- bination with acids or other chemicals. It is used to correct the yellowish tint which may remain in the clothes after washing. A neutralizing agent or what the laundrymen call a ”sour” is used in one of the rinses. It is important to use a neutralizer which will not weaken or "tender" the fabric since it dries in the clothes. T. D. Snell13 gives the following reasons for using a sour: (1) To neutralize the alkali from.the soap, soap builders, and bleach used in pre- vious steps. (2) To neutralize the natural alkalinity of the water supply, which is present as sodium bicarbonate after softening. (3) To remove stains, either those not removed in previous operations or those picked up during the process. He says that sours are believed to be harmful to the strength of the fabric only when they are not rinsed -12- out thoroughly. In a study of temperatures used in laundering at Pennsylvania State College, H. I. Carson3 found that a temperature of 820 to 85° C. was most effective for the removal of deeply embedded soil, and recommends a temperature of 600 to 62.80 C. as the most satisfactory at which to wash. He also found that in order to remove most stains in laundering, a low washing temperature is needed for removal of certain stains, followed by high washing temperature for removal of other stains -- par- ticularly those containing some grease. The formula set up by the State of Pennsylvania is found on page 13. Bath 1. 2. 3. h. 5. 6. 7. 8. 9. IO. -13- COMMONWEALTH or PENNSYLVANIA WASHING FORMULA Water Time Level Temperature Suds Bath Supplies TpH Min. t- lOO-llOOF Heavy suds c-st comp 10.15 10 t- 125-1to°r Heavy suds 0-55 comp 10.2 10 A” 160°? Heavy suds C-55 comp 10.3 10 A) IO A) +4 6-55 comp3 10.7 10 & bleach AR l60°F Heavy suds sn 160°F as 16003 85 160°r 8* 125-1c00r h” 125°F Sour 5.9 WWWWWW 8* Cold 1. 2. 3. h. 165 gms. of low titre soap, specification C-SA of the Commonwealth of Pennsylvania, composed of the following: 59-65% soaP. 7-9% tri sodium phosphate, 10-1h% sodium carbonate, and.moisture and volatile matter 18%e ' 100 gms. of high titre soap, specification 0-55 of the Commonwealth of Pennsylvania, consisting of these components: 69% soap, 9% tri sodium phos- phate, 7% sodium metasilicate, lh% sodium.carbonate. The bleach used was a 1% solution of sodium.hypo- chlorite. .An amount equivalent to 2 qts. of this diluted bleach solution was used for each 100# of dry fabric. The sour used was sodium acid fluoride, with 335 cc of a solution made up of 30 gms. of the fluoride in.one liter of distilled water. vlh- METHODS OF PROCEDURE A. Selection of the Sheets Nine brands of sheets were used for this inves- tigation. They were divided into three groups depending upon type, with three different brands of sheets in each group. The brands represented were: Forest City, Nationwide, Cannon, Utica, King, Dwight Anchor, Harmony House, Duracale, and Golden Dawn. Type refers to the thread count per inch. In this instance types 128, lhO, and 180 were used. These types are referred to by the trade as mediumweight muslin, heavyweight muslin and utility percale, respectively. By using three types of sheets in this way, a better comparison could be made of their performance in institution use than if the study were confined to one quality. The sheets were obtained from.JObbers and in- dividuals interested in the study. NO manufacturer knew that the sheets were to be tested; therefore the quality was the same as any consumer buyer might have purchased on the Open market, either at retail or wholesale price. B. Making Of the Test Pieces 1 Two sheets from each brand were out into pieces 2h" by 21' and then assembled to form a composite sheet. -15- No pieces were taken nearer the salvage than one tenth the width of the fabric which is in compliance with A.S.T¢M.h requirements for the breaking strength tests. The pieces were made 2h" long in the direction of the warp and 20' wide in the direction of the filling yarns or weft. In order to insure that no section would lose its identity, each piece was labeled with its full name in the lower left hand corner with a laundry marking pen. Pieces from.each of the nine sheets to be tested were combined into a composite sheet. Test specimens from.each type and brand were sewed together in such a way that the composite sheet was made up of three sections. Each section represented each of the three brands of the same thread count. Eighteen such sheets were made, and in each the sheet samples were placed in the same relative position. The samples were Joined by flat felled seams to cover all of the raw edges and the sides were hemmed to a width of approximately one-half inch. (See diagram of composite sheet on page 16). I The purpose of combining the specimen pieces into composite sheets was to make certain that samples of all of the sheets tested were given the same treat- ment. Therefore the various samples had the same number of washings and ironings with the same handling through- out. -l6- Figure l Nationwide Utica Golden Dawn 128 1A0 T80 Cannon Dwight Anchor Duracale 128 .IAO 180 Forest City A King Th0 Harmony House 180 ,Diagram of Composite Sheet Two laundries participated in the study, the Ingham.County Sanitorium, representing an institution laundry, and the Michigan State College Laundry, which, while an institution laundry, is more nearly comparable to a commercial laundry in that it operates on a much larger scale and the type of laundry done is more varied. The Ingham.County Sanitorium.is a hospital for tubercular patients and the type Of laundry done is prhmarily limited to uniforms, table linens, bed linens, and towels. The .Michigan State College Laundry limits its work only to departments of the college and students and staff, which would constitute the laundering of uniforms, bed linens, table linens, towels, and personal apparel. 0f the eighteen composite sheets, eight were laundered at the Ingham County Sanitorium and eight at the Michigan State College Laundry; two being kept as controls or for the testing of initial properties. At each laundry the sheets were washed for four different periods, each period consisting Of 50 launderings. Two sheets were withdrawn after each period Of 50, 100, 150 and 200 launderings respectively. The two sheets, which were kept for initial testing, were laundered three times to remove all soluble sizing before testing for initial physical characteristics. -18... C. Launderinngrocedures 1. Comparison Of the methods used at Ingham County Sanitorium.and at Michigan State College. Athichigan State College the sheets were placed in the washer, an American Laundry machine, with any load of white clothes which happened to be ready for washing. They were given the same treatment as any load Of clothes which came into the laundry in the ordinary run Of busi- ness. The washwheel was loaded with a lot weighing approximately two hundred and seventy pounds. The first water, called the ”break”, has a temperature of about 100°F. and this wash runs for ten minutes. In the ”break”, about four quarts of soap* and one half pound Of yellow*f is added to eighty gallons of water. The next water is a hot suds with the temperature at 11.0%. The soap solution is added after the washer is started and while the wheel is turning down, in order to get the solution into the water rather than upon the clothes. It also prevents splattering that would occur if it were added when the wheel was turning upward. The soap * White Ribbon Soap Chips. Solution made Of eight pounds of soap chips to 100 gallons Of water. **Wyandotte Yellow Hoop Soda. It is a tri-sodium phosphate base, builder and softener. -19- solution is used hot to enable it to make suds more easily and quickly. Eighty gallons Of water is used for this suds and about two quarts Of soap, and it runs for ten minutes. This is followed by a second suds. The amount Of water is the same, eighty gallons, and the running time ten minutes. The temperature is increased to 1600?. and the soap decreased to one quart. The third and last suds is also run in eighty gallons of water for ten minutes at a temperature Of 170°F.; one pint of soap is used, and two quarts Of Ecco-Chor liquid bleach, a very weak bleach, is added*. Three rinses follow in one hundred and fifteen gallons Of water at a temperature Of 1700F. for five minutes. The fourth rinse is run in only sixty gallons of water at a temperature of 180°F. for five minutes and has two ounces Of sour** added to it. The purpose Of the sour is to neutralize the natural alkalinity Of the water supply, which is present as sodium bicarbonate after softening. It also removes stains, either those not removed in previous Operations or those picked up during the process.1'3 * About .2% **‘Bluefix -20- The last rinse is done in one hundred and thirty- five gallons Of cold water to which was added a blue*, and it is run for five minutes. When the washing is finished, the clothes are loaded into a truck and taken to the extractor. After being loaded in it, the moisture is nearly all removed from the wash by whirling. The test sheets are then ready to go through the same washing procedure again. The water used at the Michigan State College Laundry came from the College water supply which is de- rived from deep wells. It is zeolite softened at the College power plant to as nearly zero grains Of hardness as possible. The sheets laundered at the Ingham County San- itorium.were washed with the hospital sheets in one hundred and twenty-five pound loads in an American Cas- cade washwheel. The washer is smaller than the one used at the college laundry, consequently the loads washed were smaller. The washing process begins with a three minute 'break' in warm water, about lOOOF., and‘with one hundred and twenty inches of water in the washwheel. This is followed by the suds in five inches of water at lhOOF. for ten minutes, to which has been added an alkali, * Speares' Solblue -21- orthosilicate, and one pound of powdered soap, Amber flakes*, and one pint of a one percent chlorine bleach. The second suds is run for ten minutes in five inches of water at 165°F., with one-fourth pound Amber soap and one-half pound alkali. The first rinse is done in five inches of water for three minutes at a temperature between 160-1650F., to which has been added one half pint of Calgon.** This is followed by three more rinses in twelve inches of water for three minutes each at 1650?. The fifth.rinse is done in warm water for five minutes. Sour*** is added to the next rinse in five inches of warm water for five minutes. Cold water is added to bring the water up to sixty inches in the washwheel, and the blue is added and run for five minutes. Lansing city water is used which has three grains of hardness. The washing formulas of the two laundries differ in a few respects. The college laundry runs three suds and five rinses, whereas the hospital laundry runs only two suds and seven rinses. The hospital laundry uses * Amber Flakes-~a yellow soap. ** Calgon--a complex molecularly dehydrated phOSphate. Its reaction in solution is slightly acid towards soap, which makes it desirable to employ a buffering agent which will bring up its pH to 8.5. **f Diamond Alkali Sour -22- a weak chlorine bleach in the suds and Calgon in the rinse. The amount of water used is about the same, but ’it is measured on a different basis since the washwheels are not the same Size. A formula of the laundries is tabulated in the appendix. 9. Laboratory Tests 1. Yarn count and yarn twist. It was necessary to check the yarn count so that the investigator made certain that the sheets in this study.met the specification set up for thread count as stated on their labels. The determinations were made on the new, unwashed sheets. The procedure used in determining the number of yarns per inch was carried out in accordance with A.S.T.M.h A Suter Micrometer was used in counting the yarns in three places on the sheet for both warp and filling yarns. An average of these determinations was made and recorded. The Suter Twist Tester was used to determine the number of twists per inch. Ten warp yarns and ten filling yarns were reveled from.the new, unwashed sheets in such a.manner as not to alter their twist. Each yarn was then securely clamped in place in the machine. The number of turns necessary to untwist and retwist the yarn until it broke was recorded in each case. For each of the nine original sheets tested, an average of ten -23- determinations was used in reporting the amount of twist per inch for the warp and filling yarns. 2. Tensile Strength. The samples for testing the tensile strength by the reveled-strip method were prepared according to directions set up by Federal Speci- fications, in the Commercial Standards Bulletin 0859-hh. Two sets of five specimens one and one-fourth inches by six inches from.each test sheet were cut with the longer dimension.parallel to the warp and two similar sets of five specimens each parallel with the filling. Each strip was reveled to exactly one inch in width. No two strips were cut on the same yarns in the first set which was to be tested when dry. The second set of strips were cut along the same yarns as the first set, and these were to be tested when wet. By testing the same yarns wet and dry, a better comparison could be made of their strength. The samples to be tested when wet were allowed to stand two hours or more in water at room temperature before testing. The School of Home Economics at Michigan State College does not have a conditioning room. In order to keep the dry samples at a more nearly constant temperature and humidity so that the tensile strength would be uni- form within one test sheet and throughout the study, the dry specimens were conditioned in a dessicator for twelve -24- hours before testing. A 36% solution of sulfuric acid was placed in the bottom of the dessicator, and a per- forated porcelain plate held the samples in the center of the dessicator. The machine used in testing the tensile strength was the Scott Tester. It is a pendulum type testing machine, electrically Operated, and is built in such a way that one end of the specimen is held by a moving clamp Operated at a constant speed while the other end is held by a clamp attached to a weighing.mechanism. The number of pounds at which the specimen is broken is recorded on a scale. 3. Strength of the fabric based on tensile strength after abrasion. The wearability of a fabric can, to a certain extent, be measured by its resistance to abrasion. Laboratory tests have been conducted by the rabric Research Laboratories, Inc. at Boston to discover certain physical properties which would determine the abrasion--resistance of a fabric. Ernest R. Kaswelllo, of the Laboratories says results show the reduction in tensile strength provides the best known criterion for measuring extent of abrasion. The method consists of abrading portions of a fabric for varying numbers of cycles and then determining resulting strength losses. The machine used in this study was the Taber Abrader. It is an electrically driven machine, censisting -25- of a turntable four inches in diameter, which rotates at a constant rate of speed in a horizontal plane. The fabric to be tested is securely fastened to this turn- table. TWO rubber emery composition wheels rest on the turntable in such a manner that they are free to rotate in a vertical plane. The lines of abrasion are in the form of two arcs crisscrossing each other which results in a circular path on the fabric. The turntable moves but the wheels do not. .A counter records each cycle of the turntable. The rubber emery wheels should be dressed on emery paper for 225 cycles after every 500 cycles. .A test Of this kind when performed on sheets should show a comparative rating for wearability. In order to compare one type of sheet with another, a constant number Of abrasion cycles should be used to indicate wear rather than to allow the samples of the sheets to run for dif- ferent lengths of time which would show varying degrees of wear. To set up this constant number it was necessary to know the abrasive resistance of each sheet in the study. In order to test the abrasive resistance, a sample Of each sheet was run on the abrasion machine until it showed the first signs of wear and continued until a hole was produced. The point at which one yarn, either warp or filling, broke was regarded as the first sign of wear. The hole stage was at the point at which one warp and one filling yarn broke at the same spot. -26- Since the results of this experiment are based on the tensile strength of the abraded samples, there had to be enough strength left in those samples after abrasion so as to be recorded on the tensile tester. Therefore it was decided that in order to insure a sufficient amount of strength in the samples, it would be best to take the fabric with the least abrasive re- sistance, in other words, the lowest number of cycles, and subtract from that number 100. The arbitrary figure used as the constant number at which all of the remaining test samples would be run was 200 cycles. This left enough strength in the material for breaking and assured enough strength in the remaining samples for giving a fairly accurate comparison of the tensile strength after abrasion of all groups of sheets. When the constant figure had been decided upon, three samples of each test sheet that had been washed 100 and 200 times in both laundries were run on the abrader, as well as samples from.the control sheet which had been washed only three times for the removal of soluble sizing. 1 Modified A.S.T.M. strip samples were cut from the circular abraded fabric, and tensile strengths were determined. The Scott tensile tester was used to record breaking strength, and the clamps were adjusted to a -27- one inch gauge length because each strip specimen measured one inch by two and one-half inches. The strips were allowed to stand in a dessicator, in which the humidity was controlled at 65%»and the temperature at 77°F. for at least twelve hours before testing the breaking strength. Figure 2 on page 28 shows the abraded path, size of the test strips, and the manner in which they were cut from.the abraded fabric. A. Whiteness retention. It was desirable to measure the whiteness retention of the sheets used in this study because some Of the donors wished this infor- mation which is predictive as to the degree of original whiteness the fabric will retain. The laundries in- volved were also interested in whiteness retention as the color of the fabric might indicate the effect of the laundry procedures. The Armour Research Laboratories in Chicago, Illinois, are authority for the statement that sizing and the application of heat are not the reasons for the yellowing of fabrics, but that it is more likely to be caused by the redeposition of soil during washing. This would indicate that whiteness retention is not so much dependent upon the manufacturing of the fabric as upon how it is laundered. Since Michigan State College has no equipment for A~ Anna. r;n;na...;..,t..t “was. 8- Abrade wet-Pulse, test Filll....‘... Ohm-am OF Nit-ad"! FQLI'IC -29- measuring reflectancy in fabrics, and since both laundries involved are members of the American Institute of Launder- ing at Joliet, Illinois, the laboratories of the Institute were called upon to help with this test. These labora- tories are equipped with a Hunter multi-purpose Reflecto- meter which can be used for measuring the reflectancy Of a fabric in terms of the reflection of magnesium oxide. for determining the whiteness retention of the sheets after various periods of laundering, it was necessary for them. to have samples of the original fabric and of the different sheets after the various laundering periods. The white- ness retention of the washed samples was Obtained by comp paring the reflectancy of the washed sample with that of the original material. For making these readings, samples ten inches by fifteen inches were required of each fabric. This size was necessary so that the fabric could be folded to ob- tain eight thicknesses for the reflectancy measurement. 5. Sgblgctive.Analysis. The human eye can measure to a slight extent certain qualities which make fabrics desirable or undesirable. In this study there are only a few things which the eye might measure, sudh as linting, color and wear. No specific criterion was set up for determining any of these. Comparisons of these factors were made on the new fabrics as well as after each period of laundering. -30- Linting can be noticed in two ways: (1) by the amount of nap or 'fuzzing" which is raised on the fabric and can be seen and felt after various stages in launder- ing, and (2) by the amount of lint noted on the fabric during the abrasion test. If there is a marked change in color, the eye will be able to perceive it when all of the fabrics are placed next to each other. It will not be possible to detect the degree of change in color, but if there is even a minor change, it can be seen. The eye can also determine some signs of wear, especially holes throughout the material, and signs of wear along hem edges. -31- DISCUSSION OF RESULTS The initial properties of the nine sheets used in this investigation are recorded in table 1, page 32. Yarn Count and Yarn Twist The count within each of the three types of sheets studied was found to be fairly well balanced, with one exception in the type 128 group where there was a difference of fourteen yarns more in the warp than in the filling. .All of the sheets met the minimum specifications for yarn count, and in every instance it was slightly higher than the count stated on the label, or as set up by the 0.P.A~ chart. All sheets were made Of single yarns with an S twist. Percales, as a group, had the highest twist per inch in both warp and filling yarns. Harmony House, with a twist of 2l.h in the warp and 18.2 in the filling was the highest in this group. The amount of twist in the 128 count and 1L0 count sheets was very nearly the same. They ranged from.a high of 18.9 twists per inch to 16.2 in the warp yarns, and a high of 1h.8 and low of 12.1 in the filling. In all cases the warp yarns had a higher number -32- mfiOprgaHOPOU GFHH do Oomwm N* macapwedauopeu so» so comsm as quaceon sense no comem * a.mm me on 04 on m.uam a.mam um so mean aoeaoo a.mm oo we mm «m 4.0am m.omm mm em oaeomnen n.5m «4 mm 44 mm a.mam a.n«m do no omsom scanner a.mm 54 ca me um s.mam a.mam we as «case a.mm mm as we on m.eam s.sam on we wees a.mm on we on em m.mam a.mam we as genome sewage a.mm me as as ea H.4Hm o.mam mm we seen pmonom «.4m do me mm on a.mam «.0Hm as on oesseoeesz a.mm mm .ue an as n.4am a.mam oo on .eoqqso pmg.aum as; sea massage new; message use: waaaaam new; upemsousmsos ms undom mom . doapmepom awedopfinz upweoupm cadence amaze new» pdsoo anew {HT 1*} maflfimm.ho WMHBmmemm_A4HBHZH H qum o.mm m.ae m.dm -558... «oaaoo oma . .. .. u.. ..m- u. . .. - .m.o. 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