LIBRARY, A 5r M COLLEGE. CANIPUS - E120-6M-L180 TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER. DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 506 MAY, 1935 DIVISION OF RURAL HOME RESEARCH Further Studies 0f the Effect 0f Sunlight 0n the Strength and Color of Cotton Fabrics I 2, Iii/Maura! & Mechanical IJEuA 8W u; ‘ c“ n. Isms. "' w’ W AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President mama Administration: A. B. Conner, M. S., Director R. E. Karper, M. S., Vice Director Clarice Mixson, B. A., Secretary M. P. Holleman, Chief Clerk D. R. McDonald, Asst. Chief Clerk Chester Higgs, Executive Assistant Howard Berry, B. S., Technical Asst. Chemistry: G. S. Fraps, Ph. D., Chief; State Chemist E. Asbury, M. S., Chemist . F. Fudge, Ph. D., Chemist . C. Carlyle, M. S., Asst. Chemist . L. Ogier, B. S., Asst. Chemist . J. Sterges, M. S., Asst. Chemist Ray Treichler, M. S., Asst. Chemist W. H. Walker, Asst. Chemist Velma Graham, Asst. Chemist Jeanne F. DeMottier, Asst. Chemist W. H. Garman, M. S., Asst Chemist A. R. Kemmerer, Ph. D., Asst. Chemist A. W. Walde, Ph.D., Asst. Chemist Horticulture: S. H. Yarnell, Sc. D., Chief Range Animal Husbandry: J. M. Jones, A. M. Chief B. L. Warwick, Ph. D., Breeding Investiga. S. P. Davis, Wool and Mohair J. H. Jones, B. S., Animal Husbandman Entomology: F. L. Thomas, Ph. D., Chief; State Entomologist H. J. Reinhard, B. S., Entomologist R. K. Fletcher, Ph. D., Entomologist W. L. Owen, Jr., M. S., Entomologist J. N. Roney, M. S., Entomologist J. C. Gaines, Jr., M. S., Entomologist S. E. Jones, M. S., Entomologist F. F. Bibby, B. S., Entomologist “R. W. Moreland, B. S., Asst. Entomologist C. E. Heard, B. S., Chief Inspector C. J. Burgin, B. S., Foulbrood Inspector Agronomy: -~ E. B. Reynolds, Ph. D., Chief R. E. Karper, M. S., Agronomist P. C. Mangelsdorf, Sc. D., Agronomist D. T. Killough, M. S., Agronomist J. '1‘. Vantine, Jr., M. S., Asst. Agronomist J. O. Beasley, M. S., Asst. Agronomist Publications: A. D. Jackson, Chief >em~w ‘larva Veterinary Science: *M. Francis, D. V. M., Chief H. Schmidt, D. V. M., Veterinarian "F. P. Mathews, D. V. M., M. S., Veterinarian Plant Pathology and Physiology: J. J. Taubenhaus, Ph. D., Chief W. N. Ezekiel, Ph. D., Plant Pathologist L. B. Loring, M. S., Asst. Plant Pathologist G. E. Altstatt, M. S., Asst. Plant Pathologist "Glenn Boyd, B. S., Asst. Plant Pathologist Farm and Ranch Economics: L. P. Gabbard, M. S., Chief W. E. Paulson, Ph. D., Marketing C. A. Bonnen, M. S., Farm Management ?;**W. R. Nisbet, B. S., Ranch Management **A. C. Magee, M. S., Farm Management Rural Home Research: Jessie Whitacre, Ph. D., Chief Mary Anna Grimes, M. S., Textiles Sylvia Cover, Ph. D., Foods Soil Survey: "W. T. Carter, B. S., Chief E. H. Templin, B. S., Soil Surveyor J. W. Huckabee, B. S., Soil Surveyor I. C. Mowery, B. S., Soil Surveyor Botany: V. L. Cory, M. S., Acting Swine Husbandry: Fred Hale, M. S., Chief Dairy Husbandry: O. C. Copeland, M. S., Dairy Husbandman Poultry Husbandry: R. M. Sherwood, M. S., Chief ' ‘ J. R. Couch, M. S., Assoc. Poultry Husb. Paul D. Sturkie, B. S., Asst. Poultry Husb. Agricultural Engineering: H. P. Smith, M. S., Chief Main Station Farm: G .T. McNess, Superintendent Apiculture (San Antonio): H. B. Parks, B. S., Chief A. H. Alex, B. S., Queen Breeder Feed Control Service: F. D. Fuller, M. S., Chief James Sullivan, Asst. Chief. . D. Pearce, Secretary H. Rogers, Feed Inspector . L. Kirkland, B. S., Feed Inspector D. Reynolds, Jr., Feed Inspector . A. Moore, Feed Inspector J. Wilson, B. S., Feed Inspector . G. Wickes, D. V. M., Feed Inspector J. K. Francklow, Feed Inspector cma iPifii/“AF-‘m SUBSTATIONS No. 1, Beeville, Bee County: R. A. Hall, B. S., Superintendent No. 2, Tyler, Smith County: P. R. Johnson, M. S., Superintendent No. 9, Balmorhea, Reeves County: J. J. Bayles, B. S., Superintendent No. 10, College Station, Brazos County: R. M. Sherwood, M. S., In Charge "B. H. Hendrickson, B. S., Sci. in Soil Erosion L. J. McCall, Farm Superintendent “R. W. Baird, M. S., Assoc. Agr. Engineer No. 3, Angleton, Brazoria County: R. H. Stansel, M. S., Superintendent H. M. Reed, B. S., Horticulturist No. 4, Jefferson County: R. H. Wyche, B1 S., Superintendent "H. M. Beachell, B. S , Junior Agronomist No. 5, Temple, Bell County: Henry Dunlavy, M. S., Superintendent C. H. Rogers, Ph. D., Plant Pathologist H. E. Rea, B. S., Agronomist "E. B. Deeter, B. S., Soil Erosion No. 11, Nacogdoches, Nacogdoches County: H. F. Morris, M. S. Superintendent **No. 12, Chillicothe, Hardeman County: "J. R. Quinby, M. S. Superintendent "J. C. Stephens, M. A., Asst. Agronomist No. l4, Sonora, Sutton-Edwards Counties: W. H. Dameron, B. S., Superintendent I. B. Boughton, D. V. M., Veterinarian W. T. Hardy, D. V. M., Veterinarian O. L. Carpenter, Shepherd ‘*0. G. Babcock, B. S., Asst. Entomologist No. 15, Weslaco, Hidalgo County: "P. L. Hopkins, B. S., Junior Civil Engineer W, H_ Friend, B, S., Superintendent No. 6 Denton, Danton County: P. B. Dunkle, M. S., Superintendent "I. M. Atkins, B. S., Junior Agronomist No. 7, Spur, Dickens County: R. E. Dickson, B. S., Superintendent B. C. Langley, M. S., Agronomist No. 8, Lubbock, Lubbock County: D. L. Jones, Superintendent Frank Gaines. Irrig. and Forest Nurs. Members of Teaching Staff Carrying . W. Adriance, Ph. D., Horticulture W. Bilsing, Ph. D., Entomology . Scoates, A. E., Agricultural Engineering K. Mackey, M. S., Animal Husbandry . G. Reeves, Ph. D., Biology S. Mogford, M. S., Agronomy R. Brison, M. S., Horticulture *Dean, School of Veterinary Medicine. sewpuwo S. W. Clark, B. S., Entomologist W. J. Bach, M. S., Plant Pathologist J. F. Wood, B. S., Horticulturist No. 16, Iowa Park, Wichita County: C. H. McDowell, B. S., Superintendent L. E. Brooks, B. S., Horticulturist No. 19, Winterhaven, Dimmit County: E. Mortensen, B. S., Superintendent "L. R. Hawthorn, M. S., Horticulturist Cooperative Projects on the Station: W. R. Horlacher, Ph. D., Genetics J H. Knox, M. S., Animal Husbandry . Darnell, M. A., Dairy Husbandry . Berry, B. S., Biology . . Stewart, Ph.D., Agronomy . A. Little, M. S., Entomology '40?‘ A. R. R V TAs of March 1, 1935 "In cooperation with U. S. Department of Agriculture. IIn cooperation with Texas Extension Service. “In cooperation with State Department of Agriculture. The changes in strength and color of 35 cotton fabrics were measured after each 25 hours of exposure to sunlight until 500 hours of exposure had been reached. The fabrics studied were well known brands, each in white, blue, green, yellow, lavender, and pink. The results of exposure of 22other fabrics were reported in Bulletin 474. The present report is a continuation of that study. The findings in this report confirm in general those in the previous portion-of the study and supply data for additional fabrics. It was found that the length of time for which the fabrics were exposed had the greatest effect upon loss in strength and that temperature had greater effect than relative humidity. All of the 35 fabrics lost strength as exposure increased but not equally, the losses after 500 hours of exposure varying from 14 to 60 per cent in the warp and from 21 to 76 per cent in the filling. Heavy fabrics of coarse yarns lost less than did light fabrics of fine yarns. The loss in strength of the dyed fabrics varied with the dye or combinations of dyes used, no one color being consistently more resistant in all fabrics, although in general blues were less weakened than other colors. Amo-ng the fabrics identical in struc- ture the white lost more strength than did any dyed fabrics with the exception of the pink, indicating that most of these dyes afford- ed protection against the tendering, or weakening, effect of sunlight. All white and all colored fabrics changed in color during ex- posure. Color changes were not dependent upon the color but upon the dye and depth of dyeing. Dark colors appear to fade less than light colors. Variations in loss of strength and color show the im- portance of using dyes and combinations of dyes which neither tender nor fade objectionably. Guaranteed fabrics underwent less change in color than did those not guaratneed, but “tub fast” fabrics were not light fast. Care should be taken in purchasing fabrics which are to be laundered that they be guaranteed fast to both light and washing. Results of this study suggest that where light fastness is desirable, it is not impossible to attain, nor unreasonable to demand, a minimum fastness, in dyed fabrics, of 100 hours of exposure to sunlight before fading is perceptible. CONTENTS § Page Introduction . __________________________________ __ 5 Plan of Experiment A _ _ _ _ _ , _ _ _ _ , _ __ 5 Fabrics Used in This Study ______ ,_ 5 Physical Analysis of Yarns and Fabrics 6 Methods ____________ __ 6 Results 6 Chemical Analysis of Sizes and Finishes 9 Methods 10 Results _____ __ 1O Method of Sampling Fabrics .13 Method of Exposure 13 The Effect of Exposure to Sunlight on the Strength of the Fabrics eeeeee n14 The Effect of Structure on Loss in Strength _ __14 The Relation of Size and Finish to Loss in Strength _________________________ _.20 The Effect of Dyes on Loss in Strength . ______ ..21 The Effect of Atmospheric Conditions on Loss in Strength _______________ -- 25 The Effect of Exposure to Sunlight on the Color of the Fabrics .............. 28 Spectrophotometric Analysis of the Fabrics 28 Fastness with Respect to Dyes .35 Fastness with Respect to Guarantee and Price ...................................... -39 Summary _ 4O Literature Cited 41 BULLETIN No. 506 c MAY, 1935 FURTHER STUDIES OF THE EFFECT OF SUNLIGHT ON THE STRENGTH AND COLOR OF COTTON FABRICS* MARY ANNA GRIMEs When fabrics are exposed to weather certain alterations take place with resulting changes in strength and in color. The kind and extent of these changes‘ are influenced by the nature of the fabrics and the conditions under which they are exposed. This study was undertaken to determine the changes in strength and color of certain cotton fabrics when exposed to normal conditions of sunlight, temperature, and relative humidity. Fifty-seven well-known cotton fabrics were chosen for study. The effects of exposure upon the color and strength of twenty-two of these fabrics were presented in a previous publication, Bulletin 474. The present Bulletin reports findings obtained from the study of the remaining thirty- five fabrics. PLAN OF EXPERIMENT The cotton fabrics included in this study were exposed to sunlight to determine the effect of such exposure upon the strength and color. Ex- posures were made in direct sunlight with the fabrics uncovered and in a horizontal position. The fabrics were tested after each 25-hour interval of exposure from 25 through 500 hours. Each fabric was subjected to physical and chemical analyses before exposure to determine the color, the structure of the yarn and fabric, and the nature of the sizes and finishes in the cloths. The colors of the unexposed and exposed fabrics were measured with a spectrophotometer to determine any changes taking place during each exposure period. Changes in strength were determined by comparing the breaking strength before exposure with the breaking strength after each of the 20 exposure periods. The relative effects of hours of exposure, temperature, and relative humidity were determined by correlation analysis. Comparisons were made of the changes in strength and color with respect to: structure of fabric, color, dye, finish, price, and guarantee. FABRICS USED IN THIS STUDY The 35 fabrics used in this study were broadcloths, chambrays, ginghams, suitings, and nainsooks. The broadcloths included a Brittany broadcloth in white and Superlustre broadcloth in blue, green, yellow, lavender, and pink. The ginghams included Everfast and Meadow Lane, each in.white, blue, green, yellow, lavender, and pink. With the exception of white, the same colors Were- used in a well-known brand of chambray. Ever- fast suiting was chosen as a representative of heavy cotton fabrics and ‘Submitted for publication November 6, 1934. 6 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION Bluebird nainsook for fine cotton fabric, each in White, blue, green, yellow, lavender, and pink. With the exception of the White broadcloth and white nainsook the fabrics Within each group were purchased as identical in structure but differing in color. The manufacturers of these fabrics were requested to give information concerning the dyes, finishes, and guarantees of their respective products. Permission to use trade names in this report was requested and used where granted. Physical Analysis of Yarns and Fabrics Methods. Detailed descriptions of the apparatus and methods are given in Bulletin 474 (7). All physical tests were made under controlled atmospheric con- ditions of 65:1 per cent relative humidity at 75i2° F. (7). The physical analysis of all yarns and fabrics used in this study was made for descriptive purposes and to permit comparisons of the effects of the various structural factors upon the changes in strength and color resulting from exposure to sunlight. The analysis included the determina- tions of fabric width and thickness, weight per square yard, thread count, ply, yarn size, twists per inch, breaking strength of yarn and of fabric and color measurements. The usual methods for determining the struc- ture of the yarns and fabrics were employed (7). The breaking strengths of the yarns and fabrics were measured with a Scott serigraph, using two-inch jaws and allowing a distance of three inches between the jaws and a speed of 12 inches per minute. Fabric strips were 1 inch wide by thread count and 7 inches long. The breaking strength of yarns was determined after removing for a distance of three inches the crosswise threads in the center of a strip of fabric containing 100 yarns. This method leaves 2 inches of fabric on each end of the specimen for fastening in the jaws. The average of at least 20 breaks was used for all breaking-strength determinations. The strength-count factors were determined by dividing the strength of 100 yarns by the yarn size. The strength-weight factors were obtained by dividing the breaking strength of the warp plus the breaking strength of the filling by the weight in ounces of one square yard. The twist-constants were determined by dividing the twists per inch by the square root of the yarn size. The color analyses were made with a Keuffel and Esser spectro- photometer using a magnesium carbonate block with an assumed re- flection of 100 per cent as a standard. The reflection of the specimen is expressed in percentage of the standard and is the average of ten read- ings taken at 20 millimcron intervals, from 440 to 700 millimicrons. Results. The physical analyses of the fabrics and yarns are given in Table 1. Price and Width. The retail price per linear yard was converted into price per square yard in order to place the fabrics on a comparable price basis. 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BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION there is little difference between linear and square yard prices. In the other two groups, Meadow Lane and chambray, the widths are less than 36 inches with a corresponding higher price per square yard. There is a difference of 15 cents per linear yard between the Everfast gingham and the Meadow Lane cloth but of only 10 cents per square yard of fabric. Prices of Meadow Lane and colored broadcloth show a difference of 1 cent per linear yard but approximately 4 cents per square yard. These comparisons illustrate the importance of considering the widths of fabrics when one is comparing prices. Weight and Thickness. Comparisons of conditioned weight in ounces per square yard show Everfast suiting to be much the heaviest cloth followed by broadcloth and chambray of approximately equal weight, Meadow Lane, Everfast gingham, and nainsook. A slightly different order is found in the thickness of the fabrics. The Everfast suiting is thickest and the nainsook thinnest. The Everfast gingham and chambray are of approximately the same thickness as are also the Meadow Lane cloth and broadcloth. Thread Count. In all fabrics the number of warp yarns per inch exceeds the number of filling yarns. The greatest difference occurs in the broadcloths, Where the warp yarns are twice the number of filling yarns, this relatively greater. proportion of warp yarns being a characteristic of broadcloth. In all but the nainsooks the thread counts within each group are approximately the same. These differences in the nainsook are probably due to the difference in width to which the fabrics were finished, since those with the higher thread counts are narrower. Yarn Size and Twist. All yarns in these fabrics are single-ply. The yarns vary in size from approximately 100s in nainsooks to 14s in the suitings. Approximately equal sizes are found in the warp and filling of each of the suitings and Meadow Lane ginghams. The warps are finer in the Everfast ginghams and the fillings finer in the broadcloths, chambrays, and nainsooks. The twist in’ all yarns is in the right-hand direction. There is little variation in the number of twists per inch within each group of fabrics. The twist-constants place the twists of the yarns upon a comparable basis and show the warp yarns to be more tightly twisted than the filling with the exception of the chambrays. Breaking Strength and Strength Factors. The breaking strength of one- inch warp strips given in Table 2 shows the broadcloth t0 be the strongest group of fabrics followed by the suiting, chambray, Meadow Lane, Ever- . fast gingham, and nainsook groups. The filling shows a different arrange- ment, the suiting being strongest, then Everfast gingham, Meadow Lane, chambray, broadcloth, and nainsook. The broadcloths, which were strongest in the warp direction, were comparatively weak in the filling. When the breaking strengths of\100 yarns in each direction of the fabric are compared it is found that the strength of both warp and filling de- creases in the same order from the suiting, which is the strongest, through EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 9 the chambray, Meadow Lane, broadcloth, Everfast gingham to the nain- sook. The lowest strength-weight factors occur in the suiting with com- paratively little differences among the other fabric groups. Table 2. Breaking strength, strength-count, and strength-weight 1 Breaking sterngth Breaking sterngth _ of one-inch fabric of 100 yarns in Strezlflaggaffunt strips in pounds pounds Strength- Fabric weight factor” Warp Filling Warp Filling Warp Filling l l I I 1 Broadcloth: 1 1 1 1 1 1 White 1 60.77 - 1 24.21 1 28.90 1 23.60 1 0.60 1 0.46 27.32 Blue 1 53.05 1 17.57 1 25.10 1 19.80 1 0.61 1 0.40 22.14 Green 1 52.72 1 17.79 27.40 1 16.90 0.68 0.35 22.75 Yellow 1 57.16 1 ' 20.23 30.10 22.10 0.75 0.46 24.80 Lavender ‘ 1 53.36 1 18.79 28.30 22.40 0.68 0.44 22.20 Pink 1 53.58 1 17.68 28.90 18.00 0.70 0.36 23.06 Chambray: 1 1 Blue 1 43.49 1 26.51 48.80 1 35.50 1 1.71 1 0.91 22.65 Green 1 42.04 1 30.18 * 47.60 1 35.90 1 1.86 1 0.90 22.93 Yellow 1 44.74 1 29.98 48.60 1 36.00 1 1.76 1 1.03 23.20 Lavender 45.25 1 28.70 50.10 35.10 1.80 0.91 1 22.82 Pink 45.33 30.78 51.50 33.60 1.92 0.91 23.86 Everfast Gingham: White 33.19 31.85 31.00 27.50 0.59 0.63 24.82 Blue 34.07 32.84 27.90 25.60 0 52 0.54 25 44 Green 34.13 31.92 27.80 22.40 0.52 0.49 25.80 Yellow 34.21 33.77 26.90 24.50 0.49 0.52 26.66 Lavender 36.34 34.51 28.30 25.50 0.53 0.53 27.78 Pink ‘ 1 32.01 32.07 25.00 21.60 0.47 0.46 25.23 Even-fast 1 Suiting: 1 White 50.04 37.97 81.60 66.30 5.40 4.64 19.09 Blue 47.99 34.84 75.10 67.30 5.49 4.36 18.20 Green 51.91 42.20 85.40 78.30 5.85 5.30 20.46 Yellow 1 51.11 1 36.62 79.90 1 63.00 1 5.33 1 4.38 1 18.71 Lavender 1 57.69 1 41.65 1 85.30 1 75.50 1 5.79 1 5.10 1 21.09 Pink 1 51.96 36.29 81.40 67.10 5.65 4.48 1 18.98 Meadow Lane 1 Gingham: 1 White 36.39 27.18 37.50 32.60 0.97 0.74 23.29 Blue 37.73 32.81 35.80 35.50 0.87 ‘ 0.90 26.92 Green 37.56 31.00 36.00 30.00 0.92 0.70 24.40 Yellow 37.06 29.97 37.00 30.40 0.95 0.77 24.03 Lavender 40.39 32.34 41.10 32.10 1.07 0.77 25.88 Pink 35.21 29.14 35.80 29.80 0.85 0.72 23.66 Bluebird Nainsook: White 33.59 17.67 31.00 17.00 0.70 0.26 24.07 Blue 29.08 13.88 22.10 13.40 0.35 0.16 25.57 Green 32.06 17.35 22.50 10.90 0.37 0.13 23.99 Yellow 28.84 14.56 21.50 10.00 0.35 0.11 21.59 Lavender 27.48 11.64 20.60 12.40 0.32 0.14 22.88 Pink l 31.79 I 15.38 28.90 l 13.10 i 0.45 l 0.14 30.43 lStrength of 100 yarns divided by the yarn size. ZBreaking strength of warp plus that of filling divided by the weight in ounces of one square yard. Chemical Analysis of Sizes and Finishes* The sizes and finishes, which are applied to yarns and fabrics to facilitate weaving and to enhance the appearance of the finished product, may *The author is indebted for the chemical analyses used in this report to E. B. Middleton, instructor in inorganic chemistry in the Texas Agricultural and Mechanical College. 10 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION influence the changes produced by exposure to sunlight. These added substances may inhibit or accelerate such changes (8, 16). Tests were made to determine the presence of a few of the substances frequently used in the sizing and finishing of cotton yarns and fabrics. Methods. All tests were made in duplicate or triplicate. Qualitative tests were made on the fabrics for glue or gelatin, dextrin, sugar, starch, chloride ions, sulphate ions, magnesium, barium, calcium, and zinc (16). Quantitative tests were made on the fabrics and on the warp and filling yarns separately. The total size and finish was determined by extracting water-soluble substances and fats and waxes, by stripping with caustic soda and hydrochloric acid, and by ashing. No corrections were made for mechanical losses. Results. The results of the chemical tests are given in Tables 3 and 4. The white broadcloth contained none of the finishes for which the yarns were tested, in either warp or filling. The warp yarns of all of the colored broadcloths gave positive tests for starch while only the blue and pink filling yarns gave this test. This difference suggests that the starch was used in sizing the warp yarns but in washing the finished fabric some starch was transferred to the filling yarns and not removed. The traces of dextrin found in the yarnsof some of the colored broad- cloths indicate the use of a small quantity in the finish of the fabrics. A relatively large amount of starch was found in both the warp and fill- ing of all chambrays confirming the statement of the manufacturers that these fabrics were finished with starch. Dextrin was present only in the warp; therefore it was apparently used in the sizing of the warp yarns. The presence of starch in the warp yarns of the white and pink Ever- fast ginghams suggests its use in sizing and that the desizing was not complete in these two fabrics. The Everfast ginghams were the only fabrics containing sulphate ions. None of the positive ions for which tests were made were found in these ginghams. No information is available con- cerning the finishes and dyes used, but the source may have been the antichlor, sodium thiosulphate, or sulphuric acid, used to remove the last traces of chlorine left from the bleaching agent. The presence of the sulphate ions in the filling of the white gingham contra-indicates the dyes as a possible source. No Water-soluble finishes were found in the Everfast suitings with the exception of the white, which was probably lightly starched in the finish- ing process. All Meadow Lane ginghams gave positive tests for dextrin and sodium ions. Since dextrin is present in‘warp and fillingyarns it was probably added during the finishing process. No negative ions for which tests Were made were found. The source of the sodium ions may be the sodium EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 11 bichromate and sodium perborate used in the oxidation of the dyes but this can not be true of the white. The presence of sodium ions in both white Table 3. Qualitative analyses of water-soluble finishes Warp Filling Fabric Starch Dextrin! 8-64 Starch Dextrin w! O1 h 5+ s2 Na '+ Broadcloth : i White Blue Green Yellow Lavender Pink Chambray : Blue Green Yellow trace trace + llllll IIIIII llllll llllll llllll +++++ |||||+ +l|||+ +++++ +++++l ++++ Illll Illll +++++ ++++++Ill+l ilIlI lllll IIIII Gingham : White Blue Green | Yellow Lavender Pink Everfast Suiting : White Blue Green Yellow Lavender Pink Meadow Lane Gingham : I White trace . Blue trace Green trace Yellow trace Lavender trace Pink trace Bluebird Nainsook : I White Blue Green Yellow Lavender Pink trace i i i 1 ‘l 111111 111111 111111 111111 111111 111111 111111 111111 11111+ 111111 111111 111111 111111 111111 55%;; 111111 111111 trace trace trace trace trace trace llllll llllll Hllll ++++++ ++++++ ++++++ ++++++ and dyed fabrics indicates its retention from the bleaching‘ solution or the antichlor. Dextrin, sodium, and chloride ions were found in all nainsooks. Dextrin was used in the finish. The sodium and chloride ions were probably re- tained from the bleaching and antichlor solutions. All fabrics were tested for mercerization by Lance’s method (11). Ever- fast suitings and broadcloths gave positive tests for mercerization. The other fabrics were found to be unmercerized or too slightly mercerized to give a definite reaction. 12 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION i“... v0.0 “ES 00.0 0.0.0 nofliwamfl 00.0 3.“. 305w? 0Y0 0A0 iwwxU 00.0 0A0 25m 0Y0 00.0 .323 nxoomiaZ 3502c 00.0 00A 006 00.0 00.0 HAO v0.0 00A 00.0 00.0 META AOA 00.0 004 v0A 00.0 00.0 $5 5A v0.0 AOJ» h00=w>wA S; 00.0 00A» AOA 00.0 00.0. 00.0 00A 00.0 03w 302w? vAA 00.0 006 0v.0 00.0 v0.0 00.0 00A A00 00.0 flwmnU 00.0 00.0 00A. v0.0 0v.0 w: 00.0 00A Avd 00.0 25m 00.0 00.0 :3. 00A .32. 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MGTM vwA Aw.0 00.0 00.0 00.0 00.0 00.0 00.0 v0.0 00.0 6265A 00.0 0v.0 00.0 $0. mv.0 00.0 00.0 00.0. 00.0 00.0 302m? v0.0 00.0 A00 00.0 00.0 00.0 00.0 3.... 00x0 00.20 .5910 00.0 00.0 S4. 00.0 0v.0 00.0 v0.0 00.0 00.0 004 QBFH "hdhé-ENSU 0v.m $5 00.0 00.0 00A 0AA. 00.0 00.0 00.0 3X0 _ :55 00.0 00A 0A0 A70 00A 00.0 00.0 00.0 00.0 00.0 6355A 00.0 0AA 0A0 00.0 00.0 “v.0 00.0 00.0 00.0 AOJ~ 3020? :3 wv.0 00.0 00.0 00A / m; 00.0 00.0 00.0 00.0 .620 00.0 mv.0 0v.m 00A 00.0 00.0 00.0 00.0 00.0 0v.0 _ 35m 00.0 00.0 0A0 00.0 0AA AAQ 0A0 “v.0 0v.0 A00 _ was? _ __ u séiézn imam“ @333 ammcfi wows? , ifio» was Bu.“ 0.50205 1.3.0» 0nd 3am onsummoi nmmcfi mwxaB i5» 3M ucwu uwm pcoo mum acme uwm unwo nwm "Ewe nwm and 15o» was 3.3 mpsummoi anus 3% 25o pom ammo now ammo hum 95mm Q33 ch30. musmmnmu iii n05» u: maniacs oZuaum-auzd - .. ~22. uipam EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 13 The results of the quantitative analyses given in Table 4 show the chambrays contain the greatest amount of total finish followed by the broadcloths. These comparatively large amounts are due to the presence of starch and dextrin. The Everfast and Meadow Lane ginghams, and nainsooks contain approximately the same amount of total finish and the Everfast suitings the least. All fabrics contain approximately the same amount of ash, probably from the minerals normally occurring in the cotton itself. METHOD OF SAMPLING FABRICS The specimens to be tested were chosen by a systematic random method previously devised and tested (7). Before exposures were made each fabric was marked with pencil and drawn threads to permit subsequent identification and location of each specimen in relation to every other specimen. Each specimen was marked with the number of hours of sunlight to which it was to be exposed. For testing in the warp direction each fabric was marked in columns one and one-half inches apart and in rows seven inches apart. .Each column contained five specimens and each row five groups of three specimens each, making a total of 75 specimens in the group. At least two other such groups, each containing 75 specimens, were placed consecutively length- wise of the fabric. Thus at least 225 warp specimens were tested from each of the thirty-five fabrics. For testing in the direction of the filling, the specimens were marked across the fabric perpendicular to the selvages. The columns and rows were marked in the same manner as for the warp specimens. The methods of sampling in the warp and in the filling are illustrated in Bulletin 474 (7)- Before exposure all specimens marked “original” were removed and stored in the dark until tested, approximately one month later. METHOD OF EXPOSURE The marked sections of each fabric were thumbtacked to beaver boards and exposed uncovered in a horizontal position upon the roof of a three- story building. Exposures were made between 8:30 a.m. and 4:30 p.m. on sunny days only, between May 22 and October 28, 1929 and between July 3 and September 11, 1930, making a total of 500 exposure hours. A record was kept of the hours of sunshine, temperature, and relative humidity for each 25-hour period, a sunshine recorder, a sling psychro- meter, and a barometer being used for these determinations. Readings of temperature, humidity, and atmospheric pressure were made at half-hour intervals. Each specimen was removed when the hours of exposure had reached the ~ number with which it had been marked, was stored in the dark ap- . proximately one month and then tested. Twenty 25-hour exposure periods were thus included in the 500 hours. Before each specimen was removed from adjoining specimens, its width was determined by counting 14 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION from the drawn thread the average number of threads in one inch of the fabric. The breaking strength of each exposed specimen was compared with the breaking strength of the unexposed specimens containing the same yarns. The average change in breaking strength of the various specimens for each exposure period was considered the true change in strength for that particular exposure period. These differences in strength were expressed in percentage loss or gain from the original. THE EFFECT OF EXPOSURE TO SUNLIGHT ON THE STRENGTH OF THE FABRICS Factors which may influence the strength of cotton fabrics when exposed to sunlight include the finishes, dye, the structure of the yarns and fabrics, and the environment. The combined effect of these factors upon the strength of the fabrics was expressed as percentage loss from the un- exposed specimens. These data are given in Tables 5, 6, '7, and 8. Effect of Structure on Loss in Strength \Veave. Only fabrics of plain weave were used in this study; therefore no differences in loss of strength or tendering are due to variation in Weave. Thickness and Weight. The fabrics range in thickness from the suitings as the thickest, through the chambrays, Everfast ginghams, Meadow Lane ginghams, and broadcloths to the nainsooks. In weight a slightly different order occurs, from the suitings through chambrays, broadcloths, Meadow Lane, and Everfast ginghams to the nainsooks. In resistance to tendering, the fabrics range from suitings, chambrays, Everfast ginghams, broadcloths, and Meadow Lane ginghams to nainsooks. This order is almost identical with that of thickness and not greatly different from that of weight. This indicates that the thick, heavy fabrics offered greater resistance to the penetration of light and were consequently less tendered. The Meadow Lane ginghams and Pamico suitings (7), which were dyed with the same dyes but which differ in weight, thickness, yarn, structure, and mercerization, afford an opportunity for comparison of the effect of structure on tendering by sunlight. The ginghams lost on an average twice as great a percentage of the original strength as did the suitings. The greater resistance to tendering must be chiefly due to greater resistance of the heavier fabrics to penetration by light and in part to their merceri- zation. Thick, heavy fabrics have greater resistance to tendering by sunlight than do thin, light fabrics. \ Yarn. With the exception of the chambray, in which the tendering was ap- proximately equal, the filling yarns of each group were more tendered than 15 EFFECT ‘OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 3.2 5m.2 3.2 ..5..2 mm.m5 3.2 _ 2.2 .52 5.3.5 3.55 5.3.5525. 2.5m 3.5m m...mm 3.3 .33 3.3 5...mm 5.3 3.3 .33 ....m .....5 5.5m mm...m m......m mm.55 2.3 2.3 5.3 .32 3.3 m5 3.5 23m 5.5m .......m mm.55 3.3 mwmm 5.5 m...2 5.5.5 ..m5. 3.3 25.3 3.5m 3.5 2.5m 2.3 5...5 5.53m 53.2 2.3 3.. m5.mm 3.3 53 3.3 m5..mm 2.3 5m.mm .......m 2.3 .....2 m3 3.3 5.3 3.3 55.3 2.3 3.5.5 mm.3 55.3 m...3 55.5 m5 3.3 35.3 mm.55 .53 m...3 mm.55 3.3 mm.55 5.5.5.5.. 3.3 3m mm.55 5.3 5.m.55 5...5 5.1mm ..m.2 m5.5m 3.3 3.3 mm.55 m5 ..5.m 535.5 . ..m.m5 35.5 3.3 2.5. ..m.3 5.2 mm.m mm... ....m m...m 5...... m...3 55.2 5.5.5.5 3... 5m.2 3.2 .3... mm... m5 3.5 3.5 mm.55 3.3 5.2 5.55 55...: 5.m.5 5.5+ 5... 3N 3m mm.m5 mm...5 3.3 m5...2 .....55 55.55 55.5 5.5+ m5... m3 3.5 5.5.2 5m.55 3.2 3.3 mm...5 3.5 5.2 3.5 m...5 ..3 2.2 mm.55 3... m5..2 mm... 3... mm... 3.55 3.5 5... m5 m5... mm.55 mm.5 3.2 55..m 5... m..... m5...5 5....5 m...> ..m5 5...... mm... m5. mm.55 5.55 m...m 3.5 mm... m5... 55...: m2 3.5 mm... 55.2 5.55 m...5 5...... 5.5. 55... 2.5 .3... 35 3.5. m.....5 2... 3... 5.5+ mm... 3.5+ 3... m»... 3... m.. 5.5. 35.5 55.m .....m 2.5+ m...m 5.5 . 2.m 55.5 ..5.... ..m 25.5 .3... 5... 5.m.m 3.5+ 55.... __ 2.5+ 3... 3.5+ 5.5 m5 hflhfiidfimv . 5.3 5.3 m...3 t 5.5.3 .....3 5.3 g mm.3 fl 55.3 5.3 __ 3.3 5.2 mm.55 mflzmfi. mm...m .35 mm.mm 3m... 5.5 m3... 5...... m...mm mm.55. m...mm 3.3 2.3 3m 5.m.m5. 5m...5. ..m.m.. ..m.5 5.5.3 mm.mm mm.m.. .33 3.5 m5..mm .....mm 5....5.m m5 mm.55. .....5 2...... m...5m ..m.mm mm.mm ..m.m.. mm.5 3.5 5.3 mwmm m.....m 35. .551... mm.55 .....m.. 53...... 3.3 5m.mm m...m5. 2.5 5.m..... mm.mm 2.3 m5.3 m5 3.3 2.5 3.5.. 5m.mm 3.5m mm.mm .52 5.mm ..m.5... m...mm m5... mm.55 3.. 5.m.5 mm.mm 2.5 2.3 5m.mm m.....m 3.5 2.3 ..m.mm 5.5m 3.5 m...5 m5 m2... mwwm 2.3 2.3 5.3m m5.mm 3.5.. 2.3 3.2 5.3 5.3 2.5 ..mm mm.mm mm...m .32 53.5 m5..mm 3.5m 3.5 555...... 3.5 3.3 .553 3.3 3m mm.55 3.3 m...mm 53.3 .33 5.5 mm.55 2.2 2.... .....mm 5.2 3.3 3m m5.3 _ ..m.2 _ 3.5.5.. _ 5.5.3 mm... 55.5 _ 5m.mm 55.3 5....m5 .....3 35 3.3 m5 m...2 53.3 5.55m mm.m5 mm.55 mm.55 _ .52 3.5 .....3 3.5 m.....5 3.5 .3 .553 3.5 3.2 2.3 m...55 3.3 5.5 3.3 5.5.3 ..5..2 3... 5.5m m5 2.5 3.3 .23 .355 mm.m5 mm.55 5.3 mm.55 3.3 5.2 ..m.55 ..m.m5 ..3 3.2 5.5.5 2.55 2.5. m.....5 5.5 5.2 3.2 5.5.3 5m.2 5m.m 3... m5 5.5 3.2 5... mm... 2... 5.5.2 3.2 mm.55 5.2 m...m5 5m... 2...: 35 5.... mm.2 5...... 3.2 3.5+ 3.2 mvm 35.2 5.2 ..m.2 5.2 2... m2 3.2 5... 5m.m 5m... 55...: 55m 5...... 3... m5.55 3.55 m5.5+ 55.2 ....5 3..., mm... 3.5 mm... 3.3+ 5m.5 5.2+ 5...m 2.5 3.5 5.5+ 3.2 m.. 3.5 .3... 5.5+ 3.m 5.m+ mm... 5mm+ 5...... 5.3+ m»... 3.5+ 5.5.5 ..m 3... mm... 3.5 33+ 5.m.5+ m5=m+ m...m+ _ .....m+ m.....+ 3.5+ m......+ ..5...5+ m5 55.5.5.5 5.55.5 _ @5555 55.55 55:55.5 .55.»... 9.55.5 _ 5.35 25...... 5.55.3 5.5.55.5 5.55 Ahidaamflmw 0.5.5085 Mimm HUQGQQNQ 590:0? 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UHUMOQNO £25m“ uouflwiwfl 30:0? 5 5005a 03m ‘v%‘gl*l£u%’auwéjl\ .31., iv .2 143ml... is 18 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION 3.5 Sam $4». $5 25$ “Zfimv 3x5 i 3.5 54m i 5a.? Q35 2.4% i mmdm 5N5 55mm 8.5 3am NZ; 3.3 .25“. Nqmm 3.5 i $13 Enwm i .235 MR3 No.3 i 34.3 M33 awfiflwiwfl 2.3 Nwam 05E. :2. Nqmw Mafia 3.3 i MW? $5» i E25 modw mwdm i 58¢ 3.3 3020? 22a. 3.5 $2? ~55 3.8 $5.‘ ma?" 2E3 5.3 i NW3 84$ 3.3 _ 3x3 3.3 S0950 M32. 5.5 3.2. wmdm NW5 3.5m 5W5 i 3S 8.5m i 55m $45 .543 _ 3.3“ wwdm vim $2.2“ mwwm 3mm in? 31$ $55 $5M _ 0N4; 34m i 3.5 . . . . . . . . . . . . . . -. _ .535 N35 033E _ i _ M555 Q53 355m 5L8? 35E in? $55 i ab“? M355 __ Qasfl _ 355m 522$ __ 25:» ES; _ _ _ _ _ _ sew omw~o>< wnflwwwszmwwmvmmwz umwwmwmwwwH Ewswcmw mwunfiwsO safiuwwonm uwwwuwaw “EMSE-m 3 352.83 we 35o: 2E no»? .3985» E $2 ownwcoouon o5 u: ikflh i=6 .315 .833 .3 maxi-saw é Snub EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 19 were the warp, although in a few cases there was little difference between the two sets of yarns. \ Of a total of 700 cases, including the 20 exposure periods for the 35 fabrics, in 500 cases, or 71 per cent, the filling was tendered more than was the warp. In the 3 fabric groups in which the white and the dyed fabrics within each of the groups are identical in structure, in 286, or 79 per cent, of the 360 cases, the filling was tendered more than was the warp. The tension and the twist doubtless influenced this difference. The Table 7. Summary by fabric and color of the percentage loss in strength after 500 hours of exposure to sunlight I Meadow . Broadcloth Chambray EYerfast Evqrfast Lane B1‘.1°b“d Glngham Suiting Gingham N amsook Color Average Warp —I— Warp -I— Warp -I— Warp —I— Warp —I— Warp -I— Filling Filling Filling Filling Filling Filling , I I I Whlte 1 35.49 1 ...... .. 1 35.63 1 13.52 1 64.39 49.65 40.34 Blue 1 42.16 1 25.99 1 30.11 1 13.74 1 40.29 59.90 36.20 Green 1 42.94 1 35.12 1 36.12 1 26.01 52.15 1 64.23 42.76 Yellow 41.47 27.99 I 31.80 I 20.84 55.05 62.71 39.98 Lavender 49.79 33.33 1 33.52 1 24.02 1 41.62 66.14 41.41 Pink I 48.90 34.40 1 47.68 I 27.48 56.93 56.17 45.26 I I I I I I Average I 43.46 I 31.38 I 35.81 22.60 51.82 59.60 I 41.08 warp yarns have greater tension than the filling yarns causing the filling to expose more surface to the light and to protect the warp yarns. The warp yarns, with the exception of the chambray, have a higher twist- constant than do the filling yarns. The higher twist-constant of the chambray filling probably accounts for the comparatively greater resistance to tendering of the filling in this group. The coarse yarns lost less strength than did the fine yarns as shown by the coarse suitings and fine nainsooks. Thread Count. Since the yarn size and twist differ in the warp and filling yarns of these fabrics, differences in resistance to tendering cannot be directly Table 8. Summary by color and hours of exposure of the percentage loss in strength of. three fabrics in which there is identical structure of the white and the dyed fabrics within each group Hmlrs 0f White I Blue I Green Yellow Lavender Pink I Average exposure I I I I I 100 I 11.89 I 6.14 I 7.30 I 8.54 6.41 I 7.91 I 8.03 200 22.19 6.58 I 14.20 I 14.37 16.86 I 16.66 I 15.14 300 24.98 12.27 I 14.95 I 18.72 16.41 I 13.75 I 16.85 400 33.78 25.46 I 29.47 I 30.90 26.53 | 34.02 I 30.03 500 39.68 | 29.71 36.64 I‘ 35.90 33.14 II 44.03 II 36.52 attributed to differences in thread count. However, some of the data, such as those for the blue Meadow Lane gingham, offer some proof that 20 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION resistance to tendering by light increases with increase in the number of threads per inch. Although the twist-constant is higher in the warp than in the filling of this gingham, the breaking strength of 100 yarns of each and the yarn size of the Warp and filling yarns are approximately equal. The number of Warp threads exceeds the number of filling threads per inch by approximately 12 per cent. The breaking strength of the un-g exposed fabric was l5 per cent greater in the warp than in the filling but the percentage loss in strength of ‘the warp due to exposure was only 57 per cent of that of the filling. This greater loss in strength of the filling was undoubtedly due chiefly to the difference in thread count. The greater number of warp threads per inch increased the resistance to light penetration over that of the filling. These results agree in general with the findings of other studies (5, 7, 18) that greater resistance to tendering by light is found in coarse, hard-twisted yarns, and fabrics of close weave than is found invfine, soft- twisted yarns, and fabrics of open weave. Relation of Size and Finish to Loss in Strength The losses in strength of white broadclothand nainsook cannot be com- pared directly with the colored fabrics in their respective groups because of differences in structure, as shown in Table 1. However, data in Table 5, summarized in Tables 6 and 7, show greater resistance to tendering in the white broadcloth and White nainsook than in the dyed fabrics of these two groups. The white broadcloth contained approximately the same quantity of finish as do the dyed broadcloths, but gave no positive’ test for any of the substances for which qualitative tests were made. The white nainsook contains slightly less total finish in the filling than do the dyed nainsooks but all gave evidence of containing the same finishing substances. The greater tendering of the dyed broadcloths and nain- sooks probably was not due to the finishes. The chambrays contain more added substances than any other group. The comparatively large amount of starch and the dextrin may have protected the chambrays from the tendering effect of the sun, as the chambrays show slightly less loss in strength than any of the fabrics of similar type. The Everfast ginghams and suitings and the Meadow Lane ginghams are each approximately identical in structure within their respective groups; therefore direct comparisons can be made within each group. A summary of the percentage loss in strength of the warp plus the filling of each fabric, given in Table 7, shows the white Meadow Lane to have lost much more strength than any of the dyed ginghams. Since the finish in all Meadow Lane is the same, the difference within this group cannot be attributed to finish but may be due to the fact that the resistance of this fabric was lowered in the bleaching process and that the fabric was unprotected by dye. The Everfast ginghams contain slightly less total finish than the Meadow Lane ginghams but not the same substances. The differences in finish may have had a slight effect on the greater resistance to tendering of the Everfast ginghams. EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 21 The Everfast suitings with the exception of a trace of starch in the white, contain none of the finishes for which tests were made; therefore none of the tendering can be attributed to finish. The suitings and broadcloths gave positive tests for mercerization while the ginghams and nainsooks gave negative tests. The mercerization of the suitings and broadcloths doubtless increased their resistance to tendering, as mercerized fabrics have been found to tender less than unmercerized (5, 7, 19). It is doubtful if the sizes and finishes used in these fabrics had much effect on the loss in strength. Effect of Dyes on Loss in Strength The information furnished by the manufacturers concerning the dyes used in each fabric is given in Table 9. Two firms gave the trade name of each dye; one firm stated that vat dyes were used, and three gave no information. The protective or tendering effect of each dyeing may be determined by comparisons of the losses in strength of the white with the dyed fabrics as shown in Tables 7 and 8. The total average percentage losses of strength of the warp plus those of the filling of all fabrics, ranked in order of least loss are: blue, yellow, white, lavender, green, and pink; the losses were 36.2, 40.0, 41.4, 42.8, and 45.3 per cent, respectively,——an average of 41 per cent. Variations from this order of tendering are found in the various fabric groups. Among the broadcloths, the yellow is tendered slightly less than the blue and the lavender more than the pink. Among the nainsooks the lavender is tendered more and the pink less than any other dyed nainsook. It is thought that blues and greens do not cause tendering because they have no absorption band in the near ultra-violet and that the activity of yellows and reds in tendering and fading is due to their ability to absorb light in this region (3, 9, 10, 12, 13, l4). When all the fabrics are grouped by colors, this seems true of the blue and pink, but not of the yellow or green. Identical structure within a fabric group makes possible comparison of white with dyed fabrics in Meadow Lane gingham and Everfast gingham and suiting. Comparisons of the Meadow Lane ginghams show the white to have lost more strength than any dyed gingham, indicating that the dyes used in this group afforded protection, although not all to the same extent, against the tendering effect of sunlight. The order of protective influence of the dyes in the Meadow Lane ginghams,—blue, lavender, green, . yellow and pink,—coincides with the order in the Pamico suitings, which were dyed with the same dyes, as previously reported (7). The blue, yellow, and lavender dyeings decreased the tendering below that of the white, the green had little effect, and the pink increased the tender- ing of the Everfast ginghams. The blue suiting was tendered approxi- mately equally with the white indicating that this dye had little effect, but the dyes in the yellow, lavender, green, and pink increased tendering in this order. $9.1 ..~\..n42. J;..:»Fw..._m!..._n. kuui; .4. x... k. N O z i; ............................................ .. I t MEAH T § i |||||||||||||||||||||||||||||||||||||||||||||| I HQU§U>QA A 2 i ............................................. 3O w T ................................................. .. s w s 67a d 5. MO 2 2 ..... .. iwwnw T E33 a ma awpcmomcm wfifw oi =2 a : : ............................................. i wflm N nfldw was udflu Mfimfifinfld .~.O Elm b Eucwiw Oz EOMQNEMOMCM 07H ................................. 1w .............. :wfi£>P E o5 o» wnwwomxw no mfismw? .M:m$:m “maria m EOQM PNJQ PQUEHNN 2 § .................................................... .. Xifmm R has mo 3o Q5 wExwE mo umoo t ............ .............................. .. . 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J-umnmh .h 01min? 0320M 24 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION Information from the manufacturers makes possible comparisons of the influence of individual dyes in chambrays and Meadow Lane ginghams. There is no white chambray but comparisons of these dyed fabrics show the blue and yellow to have tendered least, and the lavender, pink, and green to have tendered approximately equally. Three of the chambrays were dyed with Ponsol Yellow G, which was used alone in yellow and in combination with other dyes in the blue and green. The yellow cham- bray containing this dye alone, was less tendered than any other chambray with the exception of the blue. Since blue chambray was dyed with the same yellow dye in combination with Anthrene Blue R.C.X., the difference in tendering between the yellow and blue‘ suggests that the blue dye afforded greater protection than the yellow or that the dyes gave greater protection when used in combination. The same yellow dye was used in combination with Anthrene Jade Green in the green chambray, in which the loss in strength was greater than in either the yellow or blue. Evidently the green dye either did not add protection or this com- bination lowered the protective value of the yellow dye. The same green dye was used alone in the Meadow Lane gingham, where the loss in strength was greater than the blue or lavender but less than in either the yellow or pink, confirming the evidence that this green dye did not afford protection when used alone or in combination with Ponsol Yellow G. From comparisons of the two known yellow dyes, it seems Ponsol Yellow G offered greater protection in the chambray than did Carbanthrene Yellow G used in the Meadow Liane but the difference may have been due in part to difference in concentration, since the chambray was more heavily dyed. The pink chambray and the pink Meadow Lane gingham were dyed to approximately the same depth. The differences in tendering within each group and between the two pink fabrics suggest that the combina- tion of Sulfanthrene Pink B. G. and Sulfanthrene Pink F. F. used in the pink chambray may have afforded slightly greater protection than did the Ponsol Red B. N. used in the pink Meadow Lane. Slightly greater pro- tection was given by the Anthrene Violet B. N. used in the lavender Meadow Lane than by the combination of Indanthrene Violet B. and Ponsol Violet R. R. used in the lavender chambray. The combination of Carbanthrene Blue B. C. S. and Ponsol Violet A. R. used in the blue i Meadow Lane afforded considerable protection against tendering as shown by comparison with the other Meadow Lane ginghams. Of the thirty dyed fabrics used in this study, the six blue fabrics were less tendered than other colors with the exception of the pink in the nainsook and the yellow in the broadcloth. None of the yellow dyes in these fabrics can be said to have greatly increased tendering although the yellow Meadow Lane and yellow nainsook were tendered slightly more than all but one of the dyed fabrics within these groups. Green and lavender fabrics were in general more tendered than blue or yellow but less tendered than pink fabrics. The greatest tendering occurred among the pink fabrics, the loss being approximately equal to or exceeding that of any other color with the one exception of pink in the nainsooks. wfqqrxvv-v» - . EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 25 For 2 white and 10 vat-dyed fabrics reported in a previous study (7) the order of resistance to tendering after\300 hours of exposure was: blue, green, lavender, White, pink, and yellow. The blue, green, and lavender dyeings apparently offered protection and the pink and yellow increased tendering. When these 12 fabrics and the 35 of the present report, each after 300 hours of exposure, are compared, the order of resistance to tender- ing is: blue, lavender, pink, green, yellow, and white. Resistance to tendering is ‘not dependent upon color alone but upon the nature of the dye or combination of dyes used on the fabric. In general, the fabrics in this study, after 500 hours of exposure, ranked, in order of resistance to tendering, as follows: blue, yellow, white, lavender, green, and pink. The Effect of I Atmospheric Conditions on Loss in Strength Correlation analysis was used to measure the effect of hours of ex- posure, temperature, and relative humidity upon the change in the breaking strength of each fabric. The data secured from the readings of temperature and relative humidity which had been recorded at half-hour intervals, were averaged for each of the twenty 25-hour periods, a half hour or fraction thereof being used as a unit. The averages thus determining for each exposure period are given in Table 10. The changes in the breaking strength of the warp and filling of each fabric for each exposure period were _expressed as the percentage loss from Table 10. Average relative humidity and temperature of exposure periods of 25 hours each Relative Temp- Period N11133:; of humidity erature, Dates % ° F. 1 25 53.20 81.74 May 22, 23, June 6, 7 1929 2 50 55.57 88.62 June 10, 11, 14, 18 1929 3 75 48.74 91.53 June 18, 20, 21, 24, July 8 1929 4 100 59.88 87.95 July 9, 10, 11, 12, 15 1929 5 125 53.44 91.08 July 16, 17, 18, 19 1929 6 150 52.14 90.83 July 23, 24, August 13, 14 1929 7 175 43.75 I 91.50 August 15, 16, l9, 20, 21 1929 8 200 46.25 92.11 August 22, 23, 26, 27 1929 9 225 41.77 89.20 August 29, September 25, 26, 27 1929 10 250 41.14 84.44 September 30, October 2, 3, 7 1929 11 275 52.34 82.68 October 14, 16, 17, 18 1929 12 300 27.88 69.85 October 22, 24, 25, 28 1929 13 325 51.41 91.07 July 3, 7, 8, 9 1930 14 350 45.38 95.98 July 9, 10, 14, 15 , 1930 15 375 45.80 91.65 July 15, 16, 17, 18, 21 1930 16 400 47.88 92.03 July 21, 23, 24, 25, August 6 1930 17 425 41.74 I 95.83 August 6, 7, 8, 11, 12 1930 18 450 40.67 I 96.10 August 12, 15, 18, 19 _ 1930 19 475 43.34 I 92.21 August 20, 21, 22, 27 1930 20 500 45.77 II 88.63 II August 27, 28, September 5, 8, 11 1930 the original strength. These data were smoothed to remove random and irregular fluctuations. The data "from the fitted curves were used in the correlation analysis. The original data from which the fitted curves were derived are given in Table 5. 26 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION A significant multiple correlation coefficient between the loss in break- ing strength and hours of exposure, temperature, and relative humidity was found in the warp and filling in each of the 35 fabrics. In 62 of the 7O cases the coefficients were above .90, in 5 cases between .80 and .90, and in 3 cases the coefficients were .65, .60, and .59 for green, yellow, and blue Everfast suiting warp, respectively. These three low coefficients are due to the erratic behavior of the warp of the blue, green, and yellow suiting. It was thought their peculiar behavior might be due to sampling; therefore more specimens were tested but with similar results. No satis- factory explanation has been found. Conversion of the coefficients of multiple correlation to coefficients of determination, and read as percentages, show the hours of exposure, temp- erature, and relative humidity to account for more than 80 per cent of the loss in strength in 64 cases, 70 to 80 per cent in 3 cases, and 35, 36, and 43 per cent in-gthe three remaining cases. Part correlation coefficients (6) were determined as a means of measuring the effects of each of the three environmental factors. These coefficients are given in Table 11. The length of time for which the fabrics were exposed was found to have the greatest effect, accounting for 90 per cent or more of the change in strength inthe warp in 3O of the cases. In the warps of the yellow Meadow Lane, yellow chambray, and lavender chambray, the time of ex- posure accounted for 78, 82, and 89 per cent, respectively, and in the blue, green, and yellow suiting for 49, 27, and 44 per cent, respectively. In the filling, more than 80 per cent of the change in strength was accounted for by the effects of the duration of exposure in 32 cases. The three remaining cases were green chambray and lavender chambray and white Everfast gingham with hours of exposure accounting for 70, 73, and 79 per cent of the change in strength. The part correlation coefficients for relative humidity and temperature show that temperature had a greater effect upon the loss of strength than did relative humidity. These coefficients show that temperature accounted for approximately three times as much change as did relative humidity. The comparatively greater effect of temperature agrees with the findings of a previous study (7) in which the effects of temperature were approxi- mately one and one-half times as great as relative humidity. These find- ings are contrary to reports that humidity affects loss of strength more than does temperature. The exposure periods covered a range of 26.25° F. and 32 per cent relative humidity. Had a wider range of temperature and relative humidity been maintained than occurred under the natural conditions of exposure, a different relationship might have been established by the use of correlation calculations. To determine the direction of the effects of hours of exposure, tem- perature, and relative humidity, and to place these factors on a more comparable basis, the beta coefficients were determined as given in Table 10. The beta coefficients for relative humidity are equally divided between positive and negative signs. In half of the cases a loss in strength was accompanied by an increase in relative humidity, and in half by a .UQ>OEUH wunuauonfiow on... 0.58....» we wusoflw £255.... wnswwuoniw. was hfiwmfiss 03.203. 27 EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS _ _ _ . _ ww... _ ww...T .w... . Nww. _ .w... _ w... 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NN... 2.... ww...! 3... w... w... ..N.. .w.... 2.... _ www. .w. . .N... ....w.. 3N . w... .! ww... .2... ww... ww... 0......» . . "HES-MEG .w...! .w... www. ..N.. w.... ww... ww...! .w... .w... .w... ww... ww... ..N..“... .w...! . 3.... www.. w.N.. Nw... .ww.. S... 2...! ww... ..N.. S... 3.... .0265... .w...! .....! ww... ww... ww... N..... 3... wN... .w.... .w.... ww... w... 52.8. w..H.! w..... ww... ww... ww... www.. ..N..! w... ..... ..N... ww... Nw... 596 m: o! woo o w.w.. wNw. ..N.. ww... ..... ... . oooA nmoo mood ammo 03M ha. Ea ......! ..... w... w.w.. .w... _ ww.... ww... .N...|. ww... N..w.. w... ww... “$.40 w....! w.... ww.... ww.... .w... _ .w... ww...! ..N... .N.... .2... .w... .2... $2.23.. wN...! w... ...w.. .w... ww... _ ..... N.... w....! .N... .ww.. .w... .w.... 2...... 5...! N.. .1 .w... .5... ww... _ w... ..... w.... ww... wNw.. ww... ww... =85 3&6 _ ww...! .w... w... w... _ .w... ww...! .....! w... w... w.... .w... 3:. ww...! __ w... .w.... .w.... _ w... . . ww... Nw...! ..... .w... 3...... ww... .w.... was... wsfizouaaui _ _ _ _ _ _ _ magnum.» _ humwibss 9260a wwfifiwuwa wmpfizfiss .w....w.... 055mb... hfiEzbi wnfiwom wousazw.» 1.2.2.5.. .9250.“ lbw? _ ofipfiofi L... 250m Lflom. QZHBQM |Mw 25cm. |EwF . wiufiwfi j 1.3 350m 180E 03.3mm |N® mnfiomw qucwmufiwwou 3mm fifiuafimwmmwawwwpmnuom wacwmufiwwou wawm ..m...ufi.mfiww.m.w.ww.ww.m.%m omnnsh Mimi...” .. QHGB 28 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION decrease. This indicates that the relative humidity t0 which the fabrics were exposed had littleeffect upon the loss in strength. Of the 70 beta coefficients for temperature, 39 are positive and 31 negative indicating that in 39 of the cases an increase in loss of strength was occompanied by an increase in temperature and in 31 cases by a decrease in temperature. Correlation analysis shows the length of exposure had a much greater effect on the loss in breaking strength than did temperature or relative humidity. Temperature had a greater effect than relative humidity, in general accounting for three times as much of the change as did the humidity. These findings agree with those of a previous study (7). EFFECT OF EXPOSURE TO SUNLIGHT ON THE COLOR OF THE FABRICS The color of-none of the thirty-five fabrics remained unchanged during the exposure periods. The rate, type, and extent of color changes varied: some colors changed quickly, others slowly; some became lighter, others darker; while others changed in hue. Color measurements of unexposed and exposed fabrics were made on a spectrophotometer. Spectrophotometric Analysis of the Fabrics White Fabrics. All White fabrics became darker and more yellow as the exposure periods increased (Figures 1 to 5). The lowering of percentage reflection toward v the blue end of the spectrum was i j r i i i i i i i i i accompanied by a rise in percent- age reflection through the yellow "l- —’° portion of the spectrum. The —--—-——- >1‘? ———— —-- changes in reflection were not at "w- .___--/25"‘" _ ~80 the same rate or to the same de- ————————— "'” x ~ ~—’°—Q-—-—.»-’-'5~~l.. gree in all fabrics. The nainsook _, My" "w was the most nearly white fabric a _ before exposure, with the Everfast so ' __ .0 gingham of nearly equal whiteness. The nainsook began to show an increase in yellow color earlier than the gingham and was some- 5, 5 what more yellow at the end of g °‘ —l 500 hours of exposure. This dif- W’ m 5°" s“ W’ m 5°" ‘wmifhnzjmfljllijzjronzw ference may have been due to the structure of the fabrics, the thinner nainsook permitting greater pene- tration of the sun’s rays. The white broadcloth and Everfast gingham became more gray than the other white fabrics, darkening throughout the spectrum to a more nearly equal amount, as shown by the straighter curves in Figures 1 and 2. The white Meadow Lane, which was a creamy white before exposure, Psncsmuz REFLECTIOI ~| O 1 l I \ I I . o | | l l l Y \ BLUE GRCEN YELLOW ORANGE l0 BLUE GREEN Fig. 1. Color curves for unexposed and exposed white Brittany broadcloth. EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 29 100 1G0 1 100 I I I I I I I I I I I I \ I I I I I I I I I I I I o Z-*'__ .___. _.--- ,_. . oo=__Z~ @a ’Z.-7r=::__..>-.-"><::’_ _ 9o 9q__ (I om? ’./,.9o / {-2. . » ’ "' l. _ __. X, _ Io /'/ "z _--°""* ao /—- _so aq 25 -’ 0-" _|o _ _.._.___/ “ _/-~ ’ /o--"°' 5 o __,o¢-"°""°_-"°"“° 5 ’.»”'/ ,0’, , , - ,, ,, g r o" g // /’o/ /' / 5 ’° " .,_.<>.9..--- _ ’° s ’°* 429° "’° “’ ___,,,_--. e" m ‘Hm’, S S » §so__ H60 g 60.. _,o’ ._60 J’ so _ __ so 5q_ _bo w ___ _ 4o 40,, I40 I I I I I I I I I r I I I I I I I I I I I I I I #40 460 480 500 5Z0 540 560 5B0 600 520 640 550 580 700 540 450 I80 500 520 540 560 5B0 600 620 $40 66D 680 1W lave Iength h: nlllmlcrcml Inn length in lillhicronl Fig. 2. Color curves for unexposed and Fig. 3. Color curves for unexposed and QXDPSQd ‘Whlte Everfast glngham. exposed white Meadow Lane gingham. I 100 I I I I I I I I I I I I 1°q_ I I I I I I I I I I I I J00 _ _oIzIe_. O0__ __l0 ‘g. .Z' "g }._..__-__.Z f’ ' o }- l 90.. =_...,.__./ ‘in: . .>< ./ me ._.Z' ‘;"" . Z OZ°L-‘ 2-2 ___,(»-" 3g’; __°__.. so / . /1---;/"‘ no 0 ‘° ,, _..@--"“" E ,i~ /‘-IQQ_'_x/. _°~ ‘A: so _ f filogo-fl-n/l, _ao z i/ W” _-.-- -»- g / l’, u v, ,' ,, g wt _,/ I‘, Jo ,,, l, f, o __‘,,»’ :10._ ,____o' _1o 2 ,?9-°‘ "' a / g _ .0’ I E 01/ m w,__-o— _so E ,1 so __ A,’ _eo so_ -50 50 __ __5° lCI_ _.IO 4o _ _|o I I I I I I I I I I I I I I I I L I40 45° 49° I00 53° 54° 55° 55° 5°° 51° 54° 55° 59° 1°“ no 460 no sou s20 s40 sso sac soo s20 s40 sso sao 10o Ina lungth Ln lilllnleronl In: lungth in Illlhloronn Fig. 4. Color curves for unexposed and Fig. 5. Color curves for unexposed and exposed white Everfast suiting. exposed white Bluebird nalnsook. increased in yellow until at the end of the exposures it was a light tan in color (Figure 3). The Everfast suiting underwent less change in color than did any of theeother white fabrics, as shown in Figure 4, suggesting that the more coarse, hard-twisted yarns offered greater resistance to penetration by the sun’s rays, thus decreasing the formation of oxycellulose, which increases the yellow color in cotton (15). Blue Fabrics. Of the six blue fabrics three exhibited remarkable fastness to sunlight, one was nearly as fast, one was somewhat faded, and one had changed until the original color was unrecognizable after 50 hours of exposure. 30 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION I I I I I I I I I I I I I I I I I I I I I I I I so _ I _I so 5° - — so _ _ so 5° - - § 4o ,_. _ no § 4° - § \_ g E \- - ’\». ‘=I»i'°\‘\\ A» ‘Io- "' E ~= § \,\ E 5 ~ g0 __ \° __g° 2o __ _ o\ *3‘ u \ i °\ soo/w- ~=----.. 92,-_...,---------> o °<-u—-—° _,,o I Q2 . ‘éo l0 __ .€.6irr. _ 1o 10 _. g G - 0 I I I I I I I I I I I I o 0 I I I I I I I I I I I I 440 150 460 500 520 540 >60 5B0 600 620 640 550 6B0 7D {l0 ‘G0 430 500 5Z0 5G0 560 5G0 500 5Z0 MO 56D 6B0 700 w." llngth u lflllnicronl w-n 1on5"! in llllwvrw . Fi . 7. Color curves for unex osed and Flg, 6. Color curves for_ unexposed and expoged blue Everfast gingham p exposed blue Meadow Lane gmgham. ' ‘ ' ' I ' ' I I ' ' ' ' ' I I I I I I I I I I I F w” “w so _ _ w w” “w so > ._ so E no \° __|o E "\\ \ 54o r__ oq/c _ w a a . \ .., "I ‘"99 ' o '= é ao__ Qkffi. ___» g __ w E “ 5 ~ a zo_ “K $20 __ u, '§°-_\ ___ ___ _-':' ‘$1; _ _ :__:_-—:Z m" i” 1o _ _ 1o I, I I I I I I I I I I I I I, o ‘w m’ m’ 5°° 52° 54° m’ 55° m m’ “'9 s“ 59° "°° 24o 45o 45o soo ozo s40 sso seo soo s20 s40 sso sao no "" “m” t‘ '““‘“'°“' w." nmh in “unmoun- Fig- 3- C0101‘ Curves _ f0!‘ IITIEXDOSGd and Fig. 9. Color curves, for unexposed and exposed blue Everfast suxtmg. exposed blue chambray, .9" so I I I I I I I I I I I I | I | I I I I I | I 1 so __ _ so 9° — _ so 5°Be--~o_. .-O" "O 1o I_ ,9" _ - 1° "° —\, _ 1o _,o’l 5 - g ,<>----<=~"'°m'°’ w g u§o \. g l/'vo' ,,~—=?-1°/ — 5° § s0 __ '°_.--°’ fo/ __e0 g ’/,o"- /°’./°/ q V/@—-—°-°" Q V __ 40 ' ‘E w _ \'°_,_Q_-°-—4°\°L°-q_'—° _;g a / icy-id o~_ n‘ 5/ \\0—-0 _w |0_ t/z,\ \\.\ __40 a \¢.l5_ >//"/\ §.\ .\\.“~s~" _20 ;;°__ 0 _39 Z \ \-llq__.. .LIIIIIIIIIIIL1Q ..|1'|||I1||1\§/t.., ‘:40 cs0 A90 500 52o 540 s50 sao s00 s20 s40 s00 sac 10o “o ‘w “q 5w 5Z0 54° 550 w; gm 5:0 5w 05o no 100 Wnvl length in nflluicronn y“. 1n“; u ‘unnnqu '1‘ Fig. 16. Color curves for unexposed and Fig. 17. Color curves for unexposed and ., osed green chambray. exposed green Superlustre broadcloth. 32 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION 90 90 - I I I I I I I I I I I I I I I I 80_.. OO_- _.6O 1O 1o__ _10 I é 999/”! § so 5 ,P'-~-o / g I; °°- * ‘° 5 l! y XLLI - u E / ./ u H W E / / ‘ E E u‘) M’ ./ g ._ so E n. P‘ / 5' Z I l0 40-- / —4O ¢i'/ so so_ ,/ __ao Z IIIIIIIIIIII mIlIIIllI.IIII.. 440 I60 480 500 520 540 560 5N fill 520 640 6C) 680 100 0C0 4B0 £60 500 5Z0 MO 5G0 560 600 6Z0 M0 66D 6B0 ‘M Inn longer. In nnuurm p," 1mm h, “nun”. Fig. 18. Color curves for unexposed and Fig, 19, C0101- curves for unexposed and exposed yellow (peach) Superlustre broadcloth. I I I I I I I I I I I 9° _ 9o __,,_-._,,J.QQ.,_____,_.--¢ .0" 6° -_ '10." _ so I, I,’ ./§-u = 1o 1' ’ éhZ - / ._.g no we m 5w i=0 m w MW 6w m m m 51w 1 Wnva length in nfllllisroni WIVO length L: 111111167011! Fig. 26. Color curves for unexposed and Fig. 27 . Color curves for unexposed and exposed lavender Meadow Lane gmgham. exposed lavender Bluebird nainsook. I I I I I I I I I I I . I 1 1 1 1 1 1 1 1 1 1 1 ‘I’ - - 6° 9o _ _ao , <1 , I’. / 1o _ 1o w _ ”€,/ Z. _ m ,o—-"¢’ /’/ / / fi ea 59g‘: ' I .. 6° '- 3 -m__ , / / ,__vo II --- § w" // ' E \ _ Z9’ E °""°’ /‘ / u - x " / / E50 ,__ \,<—-—¢— fl/ V — 5° g 5° \._,. s~wlfl 1):“). _ B0 i \-\ \°-°/‘ / g > _..-- ,_; 4/ l m \i \o A- I’ /k \‘\__,.»/ l . 4o _ _ -— 4° w l/ \\ v/ 5° __.-_--?' " --_. v 9 ’ _ ' \ 1/ . \ /.__/ so \/ Z. so _ '- w \.y° ._4o - o I I I I I I I I I I I N0 160 4B0 500 520 540 560 580 600 B20 540 S50 , 580 1g‘ “uo ‘lo Jo 5L szlo Jo 6:0 sslo ‘olo 6:0 Jo 6'“, ‘£0 70;“ In" lngth tn lillhiervu "u "u". a ‘Ht-urn. Fig. 28. Color curves for unexposed and Fig. 29. Color curves for unexposed and exposed lavender chambray. exposed lavender Superlustre broadcloth. 34 ,.,_ I I I I I I | B0_ 10__ 5. 5 s “ so- ,, . 2 E , a ,° “' so__ , ‘ __so / O %. 1’ / 40__ rm’: : _l0 v&i____°____°____°_¢ / 30>‘$~><;_-—l/ 30 I 2-"? | | I I 04o cs0 oao soc s20 s40 soo s00 coo no s40 coo cs0 "no I!" llugth ll lllllllflrdnl Fig. 30. Color curves for unexposed and exposed pin~k Meadow Lane gingham. PHICHITAGE REIDCTIII PHCINTAGE RBFLWTXUI 8 S IIIIIIIIIIII‘ ‘-‘"»~-_.___,§<2Q.-" w- “I .\.92_\¢=/' D0 l4 0 460 0B0 500 5Z0 510 560 580 $00 6Z0 M0 G50 BIO ‘I W In" length h: nlllhiorun Fig. 32. Color curves for unexposed and exposed pink Everfast suiting. m,__ I I I I I 7 I j I I I I _m —90 —IO _'l'0 -.-$ 4m \ 4q___ -OD f I I I I I I I I I I I I 460 450 500 ‘$20 M0 5N $90 530 6Z9 54° 5W 55° 79° 440 Inn length in nflulioronl / Fig. 34. Color curves for unexposed and exposed pink Superlustre broadcloth. BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION I I I I I I 41-0.. 10__ § eo__ § E .. 9 w_ E E ,/ f 40,_ l/ I.’ §9____°____,§P9o ’°— \ / '\.<&°.-_.. m I I I I I I I I I I I 'I no no cs0 50o Q20 M0 sec sac aoo s20 s40 aw sao In“ ltngfl! in llllllior Fig. 31. Color curves for unexposed exposed pink Everfast gingham. I I I I I I I I I I I I 90L //,_ __ f l /'_/ \ UO_ f, -°:_~_ /'° , kw I017 5» l/ I 5 10_ P’ "' “‘ / 11/ g o or’ l," ' E2? X/ l”! §w :'\ ,-_ /°’ ,1’, / _ E ’__~“\~-~a’/ "‘°' 99°’ / ‘ ~ ~~__,_.> .__ __ / E \/=\ ---—---’°9/ . i . y » W- ' \. /' P —I‘° \ \I/Z Q . |0_ \ / _40 }' 1n I I I I I I I I I I I I ,0 ‘l0 460 4B0 500 5Z0 540 560 5B0 600 6Z0 640 560 S50 7B0 Ian length in nlllhloruu Fig. 33. Color curves for unexposed and exposed pink chambray, l0!) I00 I I I I I I I I . I I I I 90 _ ... 90 .2 so _ %£q\‘ so g g5‘? s a I g 1° .- ‘I,’ . _.. 1o § '9 a E so _ @1==-Q=----~'/. _ so _..>fl'f.0%;_?- __-.r 50 _ _. 50 40 _ (O I I I I I I I I I I I I40 46D 4B0 600 520 540 560 5B0 60? 5Z0 640 660 680 100 Nun longtlg in Iflllmlcrenu Fig. 35. Color curves for unexposed and exposed pink Bluebird nainsook. EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 35 The colors of the Meadow Lane gingham and Everfast gingham and suit- ing were of approximately the same character and depth. Only slight differences in color could be detected as the exposure periods progressed until at the close of 500 hours of exposure as shown in Figures 6, 7 and 8, all were slightly greyed With a decreased gloss. The blue of the chambray closely resembled that of the ginghams and suiting and was but slightly less fast. The spectrophotometric curve in Figure 9 shows a greater drop in the blue portion of the spectrum, or a loss in chroma, which resulted in a grayer color. The color of none of these four fabrics, Everfast gingham and suiting, Meadow Lane and chambray, could be judged objectionable even after 500 hours of exposure. Both the nainsook and broadcloth were a much lighter blue than the other fabrics, as shown by the curves in Figures 10 and 11. The broad- cloth showed loss in color at the end of the first day’s exposure and after 25 hours was a light blue-gray. After 50 hours little or no blue could be detected. Longer exposure increased the yellow color until after 500 hours the color curve in Figure 13 shows it to be of the same color as the white fabrics exposed the same number of hours. The blue nainsook became somewhat more gray after 50 hours of exposure and after 500 hours was only slightly blue. Having less color to lose than had the darker ginghams, slight losses appear relatively greater to the unaided eye than do the same losses in the darker blues, but the spectrophotometer, measuring the actual change in color, shows the loss to be greater in the nainsook than in the ginghams and suiting. Green Fabrics. . The spectrophotometric analyses of the green Everfast gingham and suiting show them to be very similar in their original color and in their reaction to the effects of sunlight (Figures 12 and 13). The gingham be- came lighter but did not change in hue, a uniform increase in percentage reflection occurring throughout the spectrum. The green suiting showed less change in color, the reflection at the maximum point remaining the same with an increase toward the ends of the curve, resulting in a slightly grayed green. In neither of these fabrics was the change in color per- ceptible until after more than 100 hours of exposure. Fading was perceptible but slight in the green Meadow Lane after 100 hours of exposure. The color in this fabric did not merely become lighter as did the Everfast gingham but became more yellow as the percentage reflection increased beyond the green portion of the spectrum (Figure 14). The green nainsook changed in like manner with the Meadow Lane cloth but to a greater extent. The percentage reflection decreased below 560 millimicrons and increased beyond this point as the fabric became less green and more gray, as shown in Figure 15. At 500 hours it was gray with only a trace of green discernible. Color changes in the green chambray were only faintly perceptible after 100 hours of exposure. Although the changes occurred later the chambray showed practically the same color changes as did the nainsook but it retained somewhat more green than did the nainsook after 500 hours. 36 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION Almost no change in percentage reflection occurred at 520 millimcorns at any of the exposure periods (Figure 16). The dye used in the green broadcloth was the most fugitive of all the‘ ' green dyes. This fabric changed from a green through a grey to a yellow during the 500 hours of exposure. At the end of the first day’s exposure color changes were noticeable and continued at a rapid rate until after 50 hours the fabric was only faintly green. The rate and extent of color changes are shown in Figure 17. Yellow Fabrics. The yellow fabrics include a wide gradation in depth of color, descending from the deep yellow of the suiting, through the chambray, Meadow Lane and Everfast ginghams to the light yellow nainsook. The curves in Figures 18 to 23, inclusive, show that this difference is largely in the wave lengths below 560 millimicrons and not in the regions of the yellow and red. It is in the region above 560 millimicrons, however, that the changes in reflection took place. All of the yellow fabrics became darker upon exposure. The degree to which they darkened is in proportion to the depth of color, as the deeper the color, the lower became the reflection through the yellow and red "wave lengths. All yellow fabrics were per- ceptibly faded before 100 hours of exposure. The changes in the nainsook and Everfast gingham were less noticeable probably because they con- tained less color originally. The similarity of the curves for the yellow nainsook and Everfast gingham and the white Meadow Lane and nainsook following 500 hours of exposure for each is shown in Figures 23 and 20, and in 3 and 5. _ The broadcloth included in this group is not all yellow but is a combina- tion of yellow and pink forming a color called peach. The curves in Figure 18 show that the color had altered considerably after 25 hours of exposure and somewhat more after 500 hours. The greatest change took place within the first 25 hours of exposure and between 460,and 580 millimicrons. Lavender Fabrics. The depth of color in the lavender fabrics ranges from very light in the nainsook, through medium depths in broadcloth, chambray, and Meadow Lane to the deeper color of the Everfast fabrics. ' The lavender fabrics show two types of color change. The darker shades in the Everfast fabrics and Meadow Lane gingham show in general an increase in percentage reflection throughout the spectrum as shown in Figures 24, 25, and 26. These fabrics were lighter and more grey after exposure but with no change in hue. The curve for the nainsook in Figure 27, shows greater change in the blue and red portion of the spectrum. The lowering of reflection in these regions shows that the grayness of the fabric has increased and that the lavender has become more pink than blue. \ A gradual straightening of the curve for the lavender. chambray shown in Figure 28 occurred as the color became more grey. After 500 hours of EFFECT ‘OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 37 exposure the color had changed from a lavender in which blue predominated to a grey in which pink was more apparent than blue. The color changes in the chambray progressed slowly in the early hours of exposure but after 100 hours proceeded at a more rapid rat-e (Figure 29). The lavender broadcloth was noticeably faded before the exposure had reached 25 hours and it continued to change color rapidly. Little permanent change occurred in the percentage reflection at wavelengths below 480 millimicrons, somewhat more above 640, with the greatest change occurring between 500 and 640 millimicrons or in the green and yellow portions of the spectrum. Pink Fabrics. Figures 30, 31, and 32 show the colors of Meadow Lane gingham and the Everfast fabrics to be very similar, to have undergone the same type of color changes, and to have changed to approximately the same extent. These three fabrics became more grey and decreased in gloss as the exposure periods increased. Perceptible changes did not occur before 100 hours of exposure and subsequent changes progressed slowly. The pink chambray was noticeably lighter after 50 hours of exposure but after 100 hours the changes occurred more slowly, the pink gradually becoming more gray (Figure 33). The color curves for the broadcloth show it to have had somewhat dif- ferent reactions to sunlight (Figure 34). After 25 and 100 hours of ex- posure the percentage reflection is seen to be practically the same as the original at the red end of the spectrum but higher below 620 millimicrons. After 500 hours of exposure the percentage reflection was lower throughout the spectrum than it was after 100 hours and the curve more nearly straight, showing the fabric to have lost much of its original pink, to be darker and more gray. The broadcloth could not be called a pleasing color after 50 hours of exposure to sunlight. The nainsook was a light pink or flesh color, as shown in Figure 35. Already quite light, it changed little during the exposure periods but at the close of the 500 hours the reflection was. less in the red region and more in the green, with approximately the same reflection in the yellow region. These changes show it to have become less pink and more yellow. From the color changes occurring in these fabrics it seems possible to secure fabrics in any of these five colors which suffer no appreciable change under 100 hours of exposure to sunlight. Fastness with Respect to Dyes The dyes used are known in only the chambray and Meadow Lane fabrics. From the color curves it is shown that the combination of Anthrene Blue R. C. X. and Ponsol Yellow G. used in the blue chambray and the combination of Carbanthrene Blue B. C. S. and Ponsol Violet A. R. used in the blue Meadow Lane were equally fast to sunlight under normal con- ditions of exposure. The fastness of the blue chambray agrees with the 38 BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION rating of Stott (17) that Blue R. C. X. has excellent fastness when used alone or in combination with Yellow G. Green Meadow Lane was dyed with Anthrene Jade Green used alone, and green chambray with the same dye in combination with Ponsol Yellow G. The combination of dyes produced a more vivid green in the chambray than did the green dye used alone in the gingham, but the chambray underwent greater color changes suggesting that the Yellow G. dye was less fast than the Jade Green or when used in combination the Yellow G. dye slightly reduced the fastness of the green dye. The Ponsol Yellow G. was used alone in yellow chambray and this fabric was changed to ap- proximately the same extent as was the green chambray, indicating further that this yellow was not only of poor fastness when used alone but that it‘also reduced the fastness of the green dye with which it was combined. When each of the two dyes is used alone the green exhibits greater fastness than does the yellow. These findings agree with Stott (17) who lists Yellow G. as having poor fastness to light when used alone and when used with Jade Green, but lists Jade Green as having good fastness when used alone. Borho (1) found that "the greater the amount of yellow used in combination with the green, the less fast the combination. Verification of this statement is found in comparison of the green Meadow Lane in which Jade Green was used alone, with the green chambray in which the green was combined with Yellow G, since the color of the Meadow Lane was changed less than the chambray. Scholefield and Turner (14) found that in mixtures of blue and yellow, the fastness of blue was decreased and the fastness of yellow increased as compared with their respective fastness when dyed alone. These conclusions are borne out in the chambray in which the blue fabric was dyed with a combination of a blue and a yellow dye. This fabric underwent greater color change in the blue portion of the spectrum than in the yellow portion. The chambray dyed with the same yellow dye used alone, changed more in the yellow portion than did the blue chambray in which the yellow dye was combined with blue dye. This was not true in the green chambray in which the same yellow dye was combined with green. Here greater change took place in the yellow portion than occurred at the green wavelengths. The same change occurred in the green Meadow Lane where the same green dye was used alone, indicating that the yellow was not responsible alone for the type of color change which occurred in the green chambray. The colors of the yellow Meadow Lane and yellow chambray were changed equally upon exposure showing the two dyes, Carbanthrene Yellow G. and Ponsol Yellow G. to be of equal but poor fastness. The lavender chambray was dyed with Indanthrene Violet B and Ponsol Violet R. R. and the lavender Meadow Lane with Anthrene Violet B. N. The chambray was affected by the sunlight to a greater extent than was the gingham but whether the less fast color was due to the use of individual dyes less fast than the dye in the Meadow Lane or to the combination of dyes in the chambray is not known. It is known that a combination of fast dyes may be less fast than either dye when used alone, or that a combination of a fast with a fugitive dye may be either EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS ~ 39 fast or fugitive depending upon the particular combination of dyes (2, 3, 9, l0, 13). Stott (17) has found Violet B. N. to possess good fast- ness to light when used alone as in the Meadow Lane. The combination of Sulfanthrene Pink B. G. and Sulfanthrene Pink F. F. used in the pink chambray produced a color less fast than the Red B. N. used in the pink Meadow Lane. The fastness of Red B. N. is listed by Stott (17) as excellent. With the exception of the two dyes used in the pink chambray which belong to the Indigoid group, all dyes invthe chambray and Meadow Lane belong to the Anthracene group of dyes. The Meadow Lane ginghams and Pamico suitings (7) were dyed with the same dyes. Comparisons of the unexposed fabrics show the suit- ings to be slightly darker than the ginghams, a change which may have been due to greater absorbtion of dyes by the mercerized fabrics. Com- parisons of color changes in these ginghams and suitings show the ginghams to have altered somewhat more, probably on account of greater resistance of the coarser suitings to the penetration of light. The green broadcloth underwent the greatest change in color and the blue Everfast fabrics and blue Meadow Lane gingham the least. Dark colors showed less color change than light colors. Among the darker colors the blues were less changed than other colors but no one color was fast in all fabrics. All white fabrics became yellow, yellow fabrics be- came darker, and other colors became lighter and more gray when ex- posed to sunlight. In general, the fabrics least faded were also least tendered. Fastness with Respect to Guarantee and Price The Meadow Lane ginghams, Everfast fabrics, and nainsooks have a “money back” guarantee. The manufacturers of chambray gave no in- formation concerning a guarantee. The broadcloths were labeled “tub fast”. The fastness of color was found to correspond in most cases to the guarantee, the Everfast fabrics and Meadow Lane gingham in all colors but yellow changing less than the other fabrics. The yellow nainsook was less changed than the other yellow fabrics. It must be remembered, however, that the nainsooks were, in most cases, much lighter in color; therefore they were less fast than they probably would have been in dyeings of greater depth (7). Undoubtedly the nainsooks would be considered by the consumer as possessing sufficient fastness for the purpose for which they are generally used. The chambrays were less fast than either the Everfast fabrics or the Meadow Lane ginghams with the exception of the yellow chambray, which changed color to approximately the same extent as did the suiting and Meadow Lane gingham but somewhat more than did the Everfast gingham and nainsook. In all colors the broadcloths were much less fast than any other fabric. To test the validity of the “tub fast” guarantee the broadcloths were boiled 4O BULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION for several minutes in a concentrated soap solution, rinsed, and dried. None of them had undergone perceptible color changes; therefore they may possibly be considered fast to washing if not placed in sunlight to dry. The retail prices at the time of purchase are given for each fabric in Table 1. Comparison of these prices on the basis of square yard, show the Everfast gingham to be more expensive than the Meadow Lane but of finer thread count. The prices of none of the other fabrics can be compared directly, as the fabrics themselves differ greatly. However, the broadcloths, which were similar to the nainsooks and Meadow Lane ginghams in price, were much less fast. _ These findings indicate that a guarantee is of value in securing fabrics which are fast to light. While fast-dyed fabrics are naturally more ex- pensive than fabrics dyed with fugitive dyes, price is not as satisfactory a measure of fastness as is the guarantee. SUMMARY Thirty-five white cotton fabrics and dyed cotton fabrics including Everfast gingham and suiting, Meadow Lane gingham, broadcloth, cham- bray, and Bluebird nainsook were exposed to sunlight under normal con- ditions of temperature and humidity for a total of 500 hours. All fabrics were analyzed before exposure and after each 25 hours of exposure to determine changes in strength and color. Each of the fabrics underwent changes in strength and color. The rate and extent of change varied greatly among the fabrics. Some lost strength and color early in the exposure periods and continued to lose at a rapid rate while other fabrics had changed little in strength and color even after 500 hours of exposure. The average loss in breaking strength of the warp plus that of the filling, of all fabrics was 41 per cent after 500 hours. These losses ranged from approximately 18 to 49 per cent in the warp and from 34 to 65 per cent in the filling. The mercerization of the Everfast suitings and broadcloths probably in- creased theirresistance to tendering. Sizes apparently had little effect. Among the fabrics identical in structure, 8 of 15 dyed fabrics lost less strength than did the White indicating that the dyes used in all Meadow Lane ginghams and the blue, yellow, and lavender of the Ever- fast gingham offered protection. The blue in the suiting apparently had little effect. The dyes of the remaining 6 fabrics apparently increased the loss in strength. The fabrics of identical structure ranked in order of resistance to the tendering effect of sunlight are: blue, lavender, yellow and green (approximately equal), white, and pink. The blue dye of the suiting offered the greatest protection and the pink of the Meadow Lane the least. It was found that certain dyes were not equally fast when used alone and in combination with other dyes. These findings emphasize the im- portance of using dyes and combination of dyes which afford protection against tendering and fading. - \ EFFECT OF SUNLIGHT ON STRENGTH AND COLOR OF FABRICS 41 The heavier, coarser fabrics were less tendered than the thinner, finer fabrics, probably 0n account of the greater resistance to the penetration of light. Correlation analysis of the environmental factors shows that the number of hours of exposure had far more effect upon the loss of strength than had temperature and relative humidity. Temperature had more effect than relative humidity, accounting for approximately three times as much change as did relative humidity. Exposure to sunlight affected the color of all white and all dyed fabrics, as determined by spectrophotometric analysis. White fabrics became more yellow as the exposure periods lengthened. Dyed fabrics varied in their color changes: some became darker and other lighter, while some changed in hue. The general tendency of most colored fabrics was to become lighter and more gray, the color curve becoming more nearly straight as the exposure increased. The greatest color changes occurred in the broad- cloths and the least in the suitings and ginghams. Dark colors in general showed less color change than did fabrics less heavily dyed. Fading was not limited to any one color or colors. All colors underwent considerable change in one or more fabrics but blue and green were in general less changed than yellow, lavender, and pink. The least faded fabrics were in most cases the fabrics least tendered by exposure. Doubtless this greater resistance to fading and tendering was due to the fact that these colors have no absorption band in the region of light most effective in changing strength and color. These findings agree in general with those of a previous study in which 22 cotton fabrics were exposed to sunlight for a total of 375 hours. This study shows that it is possible to secure colored cotton fabrics which undergo only slight changes in color and which retain much of their original strength even after 500 hours of exposure to sunlight. It is concluded that a requirement of fastness to 100 hours of exposure to sunlight before color changes are perceptible is reasonable and not im- possible to attain. Fabrics guaranteed fast to light were found to be more fast than those not guaranteed. The fabrics guaranteed tub fast were fast to washing but very fugitive in light. For cotton fabrics which are to be exposed to light and which are to be laundered, the consumer should insist that the guarantee includes fastness to both light and washing. LITERATURE CITED 1. Borho, Ernest. 1930. Light fastness of mixtures of Anthrene Jade Green ' and vat yellows. Text. World, 77:3650. 2. Cady, William H. 1931. Abnormal fading. Am. Dyestuff Reptn, 20:49. 3. William H. 1931. Peculiarities of fading. Am. Dyestuff Reptn, 4. Clark, Ormond W. 1930. Fast color dyeing in the converting plant. Am. Dyestuff Reptin, 19:55. 5. Cunliffe, P. W., Farrow, F. D. 1928. The loss of strength of cotton exposed to light. J. Text. Inst., 19:T169. 42 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. B_ULLETIN NO. 506, TEXAS AGRICULTURAL EXPERIMENT STATION Ezekiel, Mordecai. 1930. Methods of correlation analysis. John Wiley and Sons. Grimes, Mary Anna. 1933. The effect of sunlight and other factors on the strength and color of cotton fabrics. Tex. Agr. Ex) . Sta., Bul. 474. Kauffman, H. 1931. Iron: catalytic action in tendering. Z. angew, Chem., 44:858. Abs. J. Text. Inst., 23:A32. Landolt, A. 1929. Vat-dyed cotton: tendering by light. J. Text. Inst., 20:A554. Landolt, A. 1931. The tendering of dyed fabrics on exposure to light. J. Text. Inst., 22:A41. Matthews, J. Merritt. 1920. Application of dyestuffs. John Wiley and Sons. Scholefield, F, Goodyear, E. H. 1929. Action of light on cotton dyed with certain vat-dyestuffs. Mell. Textilber, 10:867. Abs. Am. Dyestuff Reptr., 19:506. Scholefield, F.. Patel, C. K. 1928. Vat-dyed cotton: tendering by light. J. Soc. Dyers. and Col., 44:268. Abs. J. Text. Inst., 20:A205. Scholefield, F., Turner, H. A. 1933. Vat dyestuffs on cotton. Text. Rec., 51:49. Dyer and Calico Print. 70:27. J. Text. Inst., 24:130. Schorger, A. W. 1926. The chemistry of cellulose and wood. McGraw- Hill Book Company. Smith, G. 1931. The chemical analysis of sized cloth. Am. Dyestuff Reptr., 20:118. Stott, P. H. 1934. Fastness of dyestuffs alone and in combination. Am. Dyestuff Reptr., 23:346. . \ yVhittaker, C. M. 1934. Fastness in Textiles. J. Soc. Dyers and Col., zl65. Zierhold, F. 1928. Inst., 1929. 20:A201. Cotton: action of ultra-violet light. Abs. J. Text.