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 ^RESEARCH 
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 Mary Ann Morris 
 
 CALIFORNIA AGRICULTURAL 
 EXPERIMENT STATION 
 
 BULLETIN 823 
 
The Effects of Atmospheric Conditions on Specific Cotton Fabrics" 
 
 W-60 Western Regional 
 Research Cooperative Project 
 
 Cooperating agencies: The agricultural experiment stations of California, Colorado, 
 Nevada, New Mexico, Oregon, and Utah. 
 
 Administrative Advisors: 1 
 
 Dale W. Bohmont, Nevada (1962-1965) 
 Sherman Wheeler, Colorado 
 
 (1959-1962) 
 D. Wayne Thorne, Utah (1957-1959) 
 
 Technical Committee Members: 2 
 
 California: Oregon: 
 
 Mary Ann Morris Janet Bubl 
 
 Elaine Carlson 
 Florence Petzel 
 
 Colorado: 
 
 Dagmar Gustafson 
 
 *w fl(19 57-i 962 ): °t2££S£L» 
 
 Marilyn Horn 
 
 New Mexico (1957-1962): 
 Julia S. Lee 
 
 Statistical Consultant: 
 
 Elmer Remmenga, Colorado 
 
 Publication Committee: 
 
 Janet Bubl 
 Dagmar Gustafson 
 Mary Ann Morris 
 
 THE AUTHOR: 
 
 Mary Ann Morris is Associate Professor, Department of Home Economics, and Asso- 
 ciate Biochemist in the Experiment Station, University of California, Davis. 
 
 Under the procedure of cooperative publications, this regional report becomes, in 
 effect, an identical publication of each of the cooperating agencies, and is mailed under 
 the frank and indicia of each. Limited supplies of this publication are available at the 
 sources listed above. It is suggested that requests be sent to one source only. 
 
 1 Dates in parentheses show periods during which individuals served. 
 
 2 Dates in parentheses show periods during which experiment station had a contributing project. All others 
 had contributing projects during the entire period 1957-1965. 
 
CONTENTS 
 
 The findings 5 
 
 Procedure 5 
 
 Fabrics 5 
 
 Outdoor exposure 6 
 
 Laboratory exposure 7 
 
 Evaluations 7 
 
 Results and discussion 8 
 
 Outdoor exposures 8 
 
 Laboratory exposures — A 14 
 
 Laboratory exposures — B 14 
 
 Comparison of laboratory exposures A and B 17 
 
 Comparison of outdoor and laboratory exposures . . . 19 
 
 Literature cited 22 
 
 Appendix 24 
 
 JUNE, 1966 
 
 In all outdoor and many indoor uses of cotton textiles the aggregate effect of 
 atmospheric conditions is destructive. These conditions, often called "weathering," 
 include such environmental factors as sunlight, atmospheric pollutants, moisture, and 
 wind. When cotton is exposed to these elements, it deteriorates in strength and appear- 
 ance until ultimately replacement becomes necessary. 
 
 The degradation of cotton by various atmospheric conditions is of interest to con- 
 sumers and technologists. Because of the many end-uses, cotton fabrics are subjected 
 to a wide range of weather conditions. In addition, cotton is the principal fiber used 
 in outdoor fabrics. Even for fabrics used indoors, atmospheric conditions can affect 
 serviceability. 
 
 Within the western portion of the United States extreme differences in atmospheric 
 conditions exist because of variations in the amount and intensity of sunlight, in the 
 amount and distribution of precipitation, altitude, and other factors. The western 
 states are therefore in a unique position, through cooperative research, to study the 
 deleterious effect of outdoor exposure on cotton fabrics. 
 
 In this study cotton fabrics were exposed outdoors to natural weathering and in the 
 laboratory to artificial weathering conditions. The cotton was exposed, up to four 
 months, outdoors at six locations differing widely in geographic and climatic condi- 
 tions. Laboratory exposures to selected components of weathering, i.e. light, heat and 
 humidity, ozone, and air movement, were made for periods up to 900 or 1,200 hours. 
 
EFFECT OF WEATHERING ON 
 COTTON FABRICS 3 
 
 The nature of the damage caused in cot- 
 ton textiles by the weather has been stud- 
 ied and reported widely. This bulletin 
 does not attempt a complete review but 
 refers only to certain pertinent reports. 
 
 The deterioration of cotton from weather 
 involves chemical or physical processes 
 and has been reviewed by Howard and 
 McCord (1960). They report that the chief 
 agencies causing chemical deterioration 
 are sunlight and mildew or rot. Other 
 chemical factors such as airborne acids 
 and alternate wetting and drying are 
 listed also, but have less effect. Physical 
 deterioration, they state, results from fiber 
 damage due to rubbing, flexing, or re- 
 peated tensioning caused by wind, alter- 
 nate freezing and thawing, and dust abra- 
 sion. The relative importance of these 
 factors varies with location and time of 
 year, and the rate of weather attack may 
 vary considerably if cotton is exposed in 
 areas of widely different climatic condi- 
 tions. 
 
 Several comprehensive reviews of the 
 action of light on cotton textiles have been 
 published (Appleby, 1949; Howard and 
 McCord, 1960; and Robinson and Reeves, 
 1961). The exact mechanism through 
 which light degrades cotton is not known, 
 but it is generally agreed to be oxidative 
 in nature. According to Egerton (1949), 
 two general mechanisms are involved in 
 the degradation of cellulosic materials by 
 light in the visible and ultraviolet ranges. 
 In the short-wave uv region (2,000-3,000 
 A), the breakdown is believed to be 
 caused by the photolysis of the cellulose 
 chains. The other type of reaction is 
 thought to involve the presence of a sub- 
 stance which can act as a photosensitizer. 
 The photosensitizing agents can absorb 
 light in the near-ultraviolet or visible part 
 of the spectrum and, in their excited state, 
 induce the degradation of cellulose (Phil- 
 lips and Arthur, Jr., 1964). 
 
 As received at the surface of the earth, 
 the solar radiation spectrum may be di- 
 vided approximately as follows: 1) ultra- 
 
 3 Submitted for publication August 17, 1965. 
 
 violet radiation ranging from 2,700 to 
 3,900 A; 2) visible radiation ranging from 
 3,500 to 7,600 A; and 3) infrared radia- 
 tion ranging above 7,600 A (Bush, 1960, 
 and Robinson and Reeves, 1961). Such 
 factors as season of year, time of day, alti- 
 tude of place, and amount of water vapor, 
 dust, and other absorbing materials in the 
 atmosphere all have a marked influence 
 on the radiation characteristics. 
 
 Fabrics to be weathered outdoors are 
 usually placed on racks facing south, at a 
 45° angle. Weathering results may be 
 considered valid only for the particular 
 conditions, time, and place of exposure 
 (Howard and McCord, 1960). Only a few 
 studies have been reported where the 
 same textile was exposed outdoors in dif- 
 ferent locations (Fels, 1940, and Pomroy 
 and Stevens, 1964). 
 
 To shorten the exposure time, samples 
 are sometimes irradiated in the laboratory 
 in a Weather-Ometer. This instrument ex- 
 poses the samples to the light of a carbon- 
 arc lamp and to a water spray. The light 
 source varies in intensity with time, and 
 it also supplies light farther into the ultra- 
 violet than outdoor sunlight. The Fade- 
 Ometer also employs the carbon-arc as its 
 light source and may be used as a labora- 
 tory source of light. 
 
 No methods specifically designed for 
 studying the effect on textiles of atmos- 
 pheric pollutants, heat and humidity, and 
 air movement in the laboratory have been 
 reported. However, studies have been re- 
 ported on controlled laboratory exposures 
 to heat (Hessler and Workman, 1959), 
 heat and moisture (Orr et ah, 1954, and I 
 Ward, 1955), air movement (Whittaker, 
 1935), and ozone (Bogaty et al, 1952, 
 and Doree and Healey, 1938). 
 
 There is some evidence that all cotton 
 fibers may not degrade at the same rate 
 when exposed to the elements of weather- 
 ing. Investigations have shown that mer- 
 cerized cotton is more resistant to sunlight 
 and to weathering than unmercerized cot- 
 ton (Cyrot, 1958, and Goldthwait and 
 Robinson, 1958). > 
 
 [4] 
 
THE FINDINGS 
 
 The six locations where samples of a cot- 
 i ton fabric were exposed outdoors for pe- 
 riods up to four months were Berkeley, 
 California; Fort Collins, Colorado; Reno, 
 Nevada; Las Cruces, New Mexico; Cor- 
 vallis, Oregon; and Logan, Utah. After 
 exposure the samples were evaluated for 
 breaking strength, cellulose fluidity, re- 
 sistance to abrasion, changes in reflect- 
 ance and color, and nonfibrous materials. 
 A fabric made of Acala 4-42 cotton 
 fiber and one made from Pima S-l fiber 
 1 were exposed in the laboratory to the 
 light of carbon-arc lamps in Fade-Ome- 
 ters; the light of a carbon-arc lamp in a 
 Weather-Ometer with intermittent water 
 spray; to heat in an oven and to varying 
 combinations of heat and humidity in a 
 relative-humidity cabinet; to ozone in a 
 fumigation chamber; and to air movement 
 in a wind tunnel. After exposure for pe- 
 riods up to 900 or 1,200 hours, cellulose 
 fluidity and breaking strength measure- 
 ments were used to evaluate changes. 
 
 These are the results of the outdoor and 
 laboratory exposures: 
 ■ • The degree and rate of degradation 
 
 of the cotton fabric exposed outdoors 
 varied widely at the different locations. 
 Outdoor exposure at California, Nevada, 
 and Oregon resulted in greater changes 
 than exposure at the other locations for 
 all properties measured except reflectance 
 and color. The longer outdoor exposure 
 lasted the greater, in general, was the 
 amount of degradation. 
 
 • Observed changes in cellulose fluid- 
 ity, breaking strength, and pH of the 
 water extract of the samples exposed out- 
 doors indicate that the deterioration was 
 
 1 caused chiefly by photochemical action. 
 
 • Both relative humidity and hours of 
 sunshine affected changes in cellulose 
 fluidity of the outdoor exposed samples. 
 A high number of hours of sunshine and 
 
 high relative humidity tended to result in 
 larger increases in cellulose fluidity; hu- 
 midity was the most important factor. 
 
 • Exposure in the laboratory of cotton 
 fabrics to heat and humidity, ozone, and 
 air movement in the absence of light did 
 not result in any appreciable change in 
 cellulose fluidity or breaking strength. 
 
 • Laboratory exposure to the carbon- 
 arc lamps of the Fade-Ometer and 
 Weather-Ometer increased cellulose fluid- 
 ity and reduced breaking strength of cot- 
 ton fabrics. 
 
 • No significant differences were ob- 
 served between the rates of degradation 
 or the relationship between fluidity and 
 strength changes for the Acala 4-42 and 
 Pima S-l cotton fabrics. 
 
 • Exposure to the light of carbon-arc 
 lamps in the Fade-Ometer or Weather- 
 Ometer resulted in similar increases in 
 cellulose fluidity. However, exposure in 
 the Weather-Ometer, with intermittent 
 spraying of the samples with water, re- 
 sulted in less loss in strength than expo- 
 sure in the Fade-Ometer. 
 
 • The proportionate differences be- 
 tween increases in fluidity values and loss 
 in strength of samples exposed outdoors 
 and in the laboratory under different con- 
 ditions of humidity indicate that exposure 
 to light in moist air resulted in nonlocal- 
 ized cleavage of the cellulose chain while 
 exposure in drier air resulted in more 
 localized degradation of the cellulose near 
 the end of the chain. 
 
 • Laboratory exposure to light in the 
 Weather-Ometer gave some indication of 
 the rate of degradation that occurred dur- 
 ing outdoor exposure at the California 
 and Oregon locations. Exposure to light 
 in the Fade-Ometer gave little indication 
 of the rate or amount of degradation re- 
 sulting from outdoor exposure. 
 
 PROCEDURE 
 
 Fabrics 
 
 The cotton fabric used for outdoor expo- 
 sures was a commercially produced 80- 
 
 square print cloth, warp yarns cotton 
 33:Z22tpi (17.7 tex), filling cotton 40: 
 Z25tpi (14.7 tex). It was bleached and 
 
 [5] 
 
desized, with no bluing, optical bleach 
 or finishing material present. 
 
 The two 80-square fabrics used for lab- 
 oratory exposures were made especially 
 for this study: one fabric from Acala 4-42 
 cotton fiber, the other from Pima S-l. 
 The warp yams were cotton 30:Z24tpi 
 (20 tex), and the filling yarns cotton 
 40:Z22tpi (14.8 tex). Finishing included 
 onlv the following: desizing and scouring, 
 bleaching with a continuous hydrogen 
 peroxide bleach, and compressional 
 shrinkage, leaving a residual shrinkage of 
 1.6 per cent. All sampling of the fabrics 
 for specific exposures was done at one of 
 the cooperating stations. 
 
 The Acala 4-42 fiber had been grown 
 near Shafter, California, and the Pima S-l 
 near Las Cruces, New Mexico. Some data 
 on the fiber follows: 
 
 Acala 
 Classification: 4-42 
 
 grade M 
 
 staple length, inches . . 1%2 
 
 Fiber length (Fibrograph): 
 upper half mean, inches 1.08 
 uniformity ratio 80.0 
 
 Fiber fineness and 
 maturity: 
 
 micronaire reading . . 4.6 
 
 predicted causticaire. . 4.6 
 
 Pima 
 
 S-l 
 
 3 
 
 l 7 /lG 
 
 1.28 
 
 80.0 
 
 3.6 
 
 3.2 
 
 Fiber tensile strength 
 
 (Pressley): 
 
 /s" gauge, index 115 115 
 
 %" gauge, grams 25.0 33.6 
 
 Outdoor Exposure 
 
 Samples were exposed outdoors at Berke- 
 ley, California; Fort Collins, Colorado; 
 Reno, Nevada; Corvallis, Oregon; Las 
 Cruces, New Mexico; and Logan, Utah, 
 for the following periods: 
 
 Dates Days 
 
 March 1-April 2 32 
 
 April 2-May 4 32 
 
 May 4-June 5 32 
 
 June 5-July 7 32 
 
 March 1-May 4 64 
 
 March 1-June 5 96 
 
 March 1-July 7 128 
 
 The samples, approximately 36 x 36 
 inches in size, were attached to frames 
 by means of casings and rods. Supported 
 by exposure racks, the bottoms of the 
 frames were approximately 2 feet from 
 the ground and were held at a 45° angle 
 from the horizontal, facing due south. 
 The front and back of the fabric were 
 fully exposed. The frames were rotated a 
 quarter turn every eight days to give 
 equal distribution of exposure to all parts 
 of the sample. 
 
 Descriptive data of exposure location 
 
 Location 
 
 Latitude 
 
 and 
 longitude 
 
 Altitude 
 (feet) 
 
 Exposure site 
 
 Surroundings of campus 
 
 Berkeley, 
 
 37°52' N 
 
 280 
 
 Roof of three-story building. Roof 
 
 Surrounded by business and resi- 
 
 California 
 
 122°16' W 
 
 
 surface asphalt covered with 
 gravel. 
 
 dential districts; often smog from 
 neighboring areas. 
 
 Fort Collins, 
 
 40°34' N 
 
 5,004 
 
 Ground, edge of campus, untend- 
 
 Bordered by residential and com- 
 
 Colorado 
 
 105°04' W 
 
 
 ed area, no shading or wind- 
 breaks. 
 
 mercial districts, some farming, no 
 large industry. 
 
 Reno, Nevada 
 
 39°32' N 
 
 4,580 
 
 Roof of one-story building. Area 
 
 Surrounded by residential area, no 
 
 
 119°49'W 
 
 
 covered by gray, unpainted 
 wood decking. 
 
 large industry. 
 
 Las Cruces, 
 
 32°17' N 
 
 3,900 
 
 On plowed ground, open area. 
 
 Rural, semi-desert area, consider- 
 
 New Mexico 
 
 106°45' W 
 
 
 
 able dust. 
 
 Corvallis, 
 
 44°38' N 
 
 386 
 
 Roof of six-story building, con- 
 
 Bordered by residential and busi- 
 
 Oregon 
 
 123°16' W 
 
 
 crete surface. 
 
 ness districts, practically no 
 smog from industry. 
 
 Logan, Utah 
 
 41°45'N 
 
 4,772 
 
 Ground, center of campus on 
 
 Bordered by residential area, no 
 
 
 1 1 1 °50' W 
 
 
 untended area, no shading 
 or wind breaks. 
 
 smog from industry. 
 
 [6] 
 
General descriptive data of the expo- 
 sure locations are shown in the box on 
 page 6. During the exposure periods 
 i weather data were collected at climato- 
 logical stations as near as possible, in 
 most cases within a mile, except for Ne- 
 vada where the station was 2.6 miles 
 away. The following data were obtained 
 for all exposure sites: 1) temperature: 
 daily minimum and maximum, 2) precipi- 
 tation: daily total, 3) wind: average 
 hourly speed, 4) sunshine: total number 
 of hours. 
 
 1 Laboratory Exposure 
 
 Laboratory exposures — A 
 
 Preliminary laboratory exposures of the 
 Acala 4-42 cotton fabric were made to 
 light, weathering, and heat for periods of 
 300, 600, and 900 hours. Light exposures 
 were made by Nevada, weathering by 
 California, and heat by Oregon. The lab- 
 oratory light source was the carbon-arc 
 lamp of a Fade-Ometer. Samples were 
 exposed at a black panel temperature of 
 145 ± 5°F for the specified number of 
 standard fading hours (Am. Ass'n of Tex- 
 tile Chemists and Colorists, 1960). The 
 carbon-arc lamp operated for 4 hours and 
 was then off for 1 hour. Hours of expo- 
 sure were counted only when the lamp 
 was on. 
 
 The weathering exposures were made 
 in a Weather-Ometer equipped with a 
 carbon-arc lamp. The instrument was 
 operated at 20-minute cycles consisting 
 of 17 minutes of light and 3 minutes of 
 water spray plus light. The black panel 
 temperature was 145 ± 5° F at the end of 
 the 17 minute period of light and 96 °F 
 at the end of the 3 minute spray-plus- 
 light period. The relative humidity of the 
 ambient air in the exposure chamber was 
 approximately 70 per cent. 
 
 Exposures to heat were made in a lab- 
 oratory oven at 145°F in the presence of 
 air. The fabric samples were suspended 
 in the oven during the exposures. 
 
 Laboratory exposures — B 
 
 In these laboratory exposures, samples of 
 the Acala 4-42 and Pima S-l fabrics were 
 exposed to light, heat and humidity, air 
 i movement, and ozone. 
 
 Samples were exposed continuously to 
 
 the light of a carbon-arc lamp in a Fade- 
 Ometer at 145 ± 5°F for 300, 600, and 
 900 standard fading hours (Am. Ass n of 
 Textile Chemists and Colorists, 1960). 
 These exposures were made by Oregon. 
 California studied the effect of an air 
 pollutant on the fabrics; samples were 
 suspended in an airtight chamber con- 
 taining ozone at 70 °F and 72 per cent 
 RH. Ozone was produced by a spark gap 
 generator, and a concentration of 40 to 60 
 pphm was maintained inside the cham- 
 ber. A Mast Portable Ozone Meter and 
 Recorder provided continuous measure- 
 ment and recording of the ozone concen- 
 tration throughout the exposure period. 
 Exposures were made in the absence of 
 light and with minimum air movement 
 for 300, 600, 900, and 1,200 hours. 
 
 Samples of the cotton fabrics were sus- 
 pended in a relative-humidity cabinet 
 with mechanical refrigeration for periods 
 of 300, 600, 900, and 1,200 hours. Within 
 the cabinet was a minimum of air move- 
 ment and light. Exposures were made by 
 Oregon under the following conditions: 
 45 ± 2 per cent RH:70, 105, and 145°F 
 95 ± 2 per cent RH:70, 105, and 145°F. 
 
 The fabrics were exposed by Colorado 
 to an artificially produced air movement 
 simulating a 40-mile-an-hour wind. An 
 institution-type refrigerator, together with 
 lead-in and return ducts, housed the cir- 
 culating air. Air movement was produced 
 by means of a 25-inch fan which was 
 driven by a 7.5-horsepower motor. Air 
 temperature was maintained at approxi- 
 mately 70 °F and relative humidity ranged 
 from 20 to 30 per cent during exposure. 
 Samples were mounted in wooden frames 
 and held in place by means of coil springs 
 assuring even tension over the 12-inch 
 square sample. Air movement over the 
 sample was equalized through use of an 
 egg-crate type straightener placed at the 
 end of the air duct leading into the area 
 where the sample was mounted. Samples 
 were exposed for periods of 300, 600, and 
 900 hours. 
 
 Evaluations 
 
 After outdoor or laboratory exposures all 
 samples were sent to one of the cooperat- 
 ing stations for the appropriate laboratory 
 
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analyses. The samples which had been 
 exposed outdoors were evaluated for the 
 following: breaking strength and elonga- 
 tion, cellulose fluidity, resistance to abra- 
 1 sion, changes in reflectance and color, and 
 nonfibrous materials. Samples exposed in 
 the laboratory were evaluated for cellu- 
 lose fluidity, and breaking strength and 
 elongation. 
 
 Breaking strength and elongation 
 
 Determinations were made on a pendu- 
 lum-type instrument by the ravelled strip 
 method (Am. Soc. for Testing Materials, 
 ■ 1960), and the strength per yarn was cal- 
 culated. New Mexico made the measure- 
 ments on the samples exposed outdoors 
 and those exposed in the "A" laboratory 
 phase. Oregon made the determinations 
 on the "B" laboratory exposed samples. 
 
 Cellulose fluidity 
 
 A modified version of ASTM D539-53 
 (Am. Soc. for Testing Materals, 1960) was 
 used for cellulose fluidity measurements. 
 The yarns were dispersed in cupriethy- 
 lene diamine hydroxide; Ostwald-type 
 viscometers were used; the yarns were 
 1 cut with hand shears to pass a #20 sieve. 
 The ASTM procedure was modified in 
 the following ways: The yarns were not 
 extracted before dispersion, a sample of 
 approximately 0.1 gm was used for each 
 individual determination, and the whole 
 operational procedure was carried out 
 under a nitrogen atmosphere. Samples 
 exposed outdoors and in the wind tunnel 
 were washed to remove foreign material 
 prior to preparation for dispersion. All 
 determinations were made by California. 
 
 Resistance to abrasion 
 
 i 
 
 Inflated diaphragm method. Measure- 
 ments were made by Colorado according 
 to ASTM D1175-55T (Am. Soc. for Test- 
 
 ing Materials, 1960). The specimens were 
 abraded until all fibers in the center of 
 the abrasion area were worn off, bringing 
 the contact points in the diaphragm and 
 head together, actuating an electrical re- 
 lay and stopping the machine. The results 
 are reported as the number of cycles to 
 reach the end point. 
 
 Impeller tumble method. The procedure 
 described in AATCC Method 93-1999 
 (Am. Ass'n of Textile Chemists and Col- 
 orists, 1960) was followed. No. 250 
 abrasive liner was used in the Accelerator 
 and the machine was run at 3,000 rpm 
 for 5 minutes. The percentage loss in 
 weight of the specimens was determined. 
 All measurements were made by Oregon. 
 
 Changes in reflectance and color 
 
 Rd (reflectance), "a" and "b" readings 
 ("a" standing for greenness-redness, and 
 "b" for blueness-yellowness) on the fab- 
 ric samples were made by California on 
 a Gardner Automatic Color-Difference 
 Meter. 
 
 Nonfibrous material and pH of 
 water extract 
 
 The samples were extracted with carbon 
 tetrachloride in a Soxhlet extraction ap- 
 paratus and the solvent-soluble nonfibrous 
 materials determined by gravimetric 
 methods similar to ASTM D629 (Am. 
 Soc. for Testing Materials, 1960). The 
 fabrics were then extracted with distilled 
 water to determine water-soluble non- 
 fibrous materials. The pH of the water 
 extract was measured. All determinations 
 were made by California. 
 
 Statistical analyses 
 
 Data were subjected to statistical analyses 
 by Colorado. Means and standard devia- 
 tions, analyses of variance, and multiple 
 regressions were computed where appro- 
 priate. 
 
 RESULTS AND DISCUSSION 
 
 Outdoor Exposures 
 
 The summary of the weather data col- 
 lected during the 128-day and the four 
 32-day exposure periods indicates consid- 
 erable climatic variation among the loca- 
 
 tions (box, page 8). During the 128-day 
 exposure period the total hours of sun- 
 shine ranged from 1,577 for Nevada to 
 815 for Oregon. Wide differences were 
 also recorded for temperature, precipita- 
 
 9] 
 
tion, and wind speed. Data for the other 
 exposure periods are given in appendix 
 table 1. The sample exposed for the sec- 
 ond 32-day period (April to May) at Ore- 
 gon was lost and therefore the data for 
 laboratory measurements are missing. 
 
 The results of the laboratory measure- 
 ments made on the cotton fabric after 
 exposure for the 128 days and the four 
 32-day periods at the six locations are 
 summarized in tables 1 and 2 and stand- 
 ard deviations for breaking strength, 
 elongation, and resistance to abrasion are 
 given in table 8A. Fluidity was measured 
 on two specimens from all samples and 
 readings were less than ± 0.5 rhes of each 
 other. Data for other exposure periods 
 are given in tables 2 A through 7 A. 
 
 Cellulose fluidity 
 
 The cellulose fluidity values for the ex- 
 posed fabrics indicate marked differences 
 in effect of exposure at the different loca- 
 tions. After 128 days of exposure the cot- 
 ton exposed in California, Oregon, and 
 Nevada had fluidity values of more than 
 25 rhes, indicating severe degradation 
 (table 1). In contrast, samples exposed 
 for the same period in New Mexico, Colo- 
 rado, and Utah all had values below 10 
 rhes, indicating only mild degradation. 
 While variations in fluidity values oc- 
 curred among the four 32-day periods, 
 California, Nevada, and Oregon-exposed 
 samples always had the highest values, 
 and Colorado, New Mexico, and Utah the 
 lowest (table 2). 
 
 Relatively small variations were found 
 among the cellulose fluidity values for the 
 samples exposed for the four 32-day pe- 
 riods at the same location compared to 
 the variations among locations. Oregon- 
 exposed samples showed the greatest var- 
 iation, 5.9 rhes, the highest values occur- 
 ring on the June-exposed samples (appen- 
 dix table 7). The samples exposed in 
 Colorado, Nevada, and New Mexico dur- 
 ing June also had higher fluidity values 
 than samples exposed during any other 
 month. 
 
 Breaking strength and elongation 
 
 The samples exposed for 128 davs in Cali- 
 fornia and Nevada lost approximately 60 
 
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 per cent in strength, and the samples ex- 
 posed in Oregon lost 46 per cent. The 
 next greatest loss was observed on sam- 
 ples exposed in New Mexico (29 per cent) 
 and Colorado (19 per cent). The samples 
 exposed in Utah lost only 10 per cent in 
 strength. The loss in breaking strength 
 was greatest for samples exposed during 
 June in all locations except California. 
 
 The first 32 days of exposure caused an 
 increase in the breaking elongation of all 
 samples. Subsequent exposure tended to 
 result in a decrease in elongation for all 
 samples, except for those exposed in 
 Utah. After 128 days of exposure the 
 samples exposed in California and Ne- 
 vada had values lower than those for the 
 unexposed cotton. 
 
 Abrasion resistance 
 
 Comparison of the values for resistance to 
 abrasion of the exposed fabrics by the 
 impeller tumble method with values for 
 the inflated diaphragm method gave simi- 
 lar results. Samples exposed for 128 davs 
 in California, Nevada, and Oregon 
 showed less resistance to abrasion than 
 those exposed at the other locations. 
 Colorado- and Utah-exposed samples 
 showed the best resistance to abrasion 
 and New Mexico samples showed inter- 
 mediate resistance. 
 
 The resistance to abrasion of the sam- 
 ples varied among the four 32-day pe- 
 riods; there was no marked trend for 
 resistance to abrasion to change with sea- 
 sonal weather variations. 
 
 Reflectance and color changes 
 
 Reflectance and color measurements were 
 made on the samples before extraction for 
 nonfibrous material and therefore reflect 
 changes due to the impingement of for- 
 eign material (dust, etc.) plus the changes 
 of the fiber per se. Exposure for 128 days 
 at all locations resulted in a decrease in 
 the reflectance of the samples, an increase 
 in the "a" readings (redness) and an in- 
 crease in "b" values (yellowness). The 
 change in reflectance was the smallest for 
 samples exposed at Oregon, approxi- 
 mately 23 per cent, and was 26 to 28 
 per cent for the samples exposed at other 
 stations. The Oregon samples also showed 
 
 [11] 
 
considerably less yellowing than samples 
 exposed at the other locations. During 
 the first 32 days of exposure all samples 
 decreased approximately 10 per cent in 
 reflectance. Additional exposure resulted 
 in continued decreases in reflectance. 
 
 Comparison of the four 32-day periods 
 shows that exposure during June resulted 
 in greater yellowing than during the other 
 months for samples exposed in California, 
 Nevada, New Mexico, and Oregon. Colo- 
 rado samples yellowed to about the same 
 extent during each of the 32-day periods 
 and the Utah samples yellowed the most 
 during April and approximately the same 
 during the other months. 
 
 Nonfibrous material and pH of 
 water extract 
 
 After 128 days of outdoor exposure the 
 samples exposed in California, Nevada, 
 and Oregon contained the highest per- 
 centage of nonfibrous material — 2.8 per 
 cent, 2.1 per cent, and 1.3 per cent re- 
 spectively. The nonfibrous material ex- 
 tracted from samples exposed in Utah 
 represented 1 per cent of the total weight 
 of the samples, and approximately 0.6 per 
 cent nonfibrous material was found on the 
 Colorado and New Mexico samples. In 
 all cases most of the nonfibrous material 
 was water soluble. The pH of the water 
 extract for the California, Nevada, and 
 Oregon samples ranged from 5.00 to 4.55. 
 Comparable values for samples exposed 
 in Colorado, New Mexico, and Utah were 
 6.60, 7.05, and 7.95, respectively. 
 
 Generally, increasing length of expo- 
 sure resulted in a larger amount of non- 
 fibrous material present on the fabric. 
 Large variations in the percentage of non- 
 fibrous material and pH of the extract 
 occurred among samples exposed for the 
 four 32-day periods. 
 
 Comparison of observed changes 
 
 While exposure of the cotton fabric at all 
 of the six locations resulted in degrada- 
 tion, the rates of change varied. The sam- 
 ples exposed at California, Nevada, and 
 Oregon tended to change more rapidly 
 than samples exposed at Colorado, New 
 Mexico, and Utah. Exceptions were re- 
 flectance and color changes. These were 
 the only measurements where the greatest 
 
 changes were not observed for California, 
 Nevada, and Oregon. 
 
 The relationship between change in 
 breaking strength and increase in cellu- 
 lose fluidity of the exposed samples is 
 shown in figure 1. The increase in cellu- 
 lose fluidity values for a corresponding 
 decrease in breaking strength was great- 
 est for samples exposed in California and 
 Oregon and least for samples exposed in 
 New Mexico. 
 
 The amount of nonfibrous material ex- 
 tracted from the exposed samples ap- 
 peared to be related to the extent the 
 cotton had been degraded. Samples with 
 high fluidity and low strength values gen- 
 erally contained a higher amount of ex- 
 tractable material and had acidic pH 
 values. The amount of nonfibrous mate- 
 rial extracted from the exposed fabric 
 was not related to the amount of change 
 in reflectance or color. No correlation was 
 apparent between loss in reflectance or 
 yellowing and cotton degradation as 
 shown by changes in fluidity and strength. 
 
 The longer exposure lasted, the greater 
 was the amount of degradation. After 128 
 days of outdoor exposure there was little 
 indication that the rate of degradation 
 was decreasing. For the fabrics exposed 
 in California, Nevada, and Oregon the 
 high fluidity values and great loss in 
 strength would indicate that the cotton 
 had been so severely degraded that the 
 future serviceability of the material had 
 been substantially limited. The fabric ex- 
 posed in New Mexico for 128 days had 
 begun to show indications of damage 
 that might impair its serviceability, while 
 those exposed in Colorado and Utah 
 showed rather mild amounts of deteriora- 
 tion. 
 
 Outdoor exposures of cotton textiles by 
 other workers (Fels, 1960; Goldthwait and 
 Robinson, 1958; Pomroy and Stevens, 
 1964; and Race, 1949) have generally 
 shown an increase in cellulose fluidity or 
 a decrease in breaking strength more 
 nearly like the values found for samples 
 exposed in California, Nevada, and Ore- 
 gon than those exposed in Colorado, New 
 Mexico, and Utah. Thus it may be sug- 
 gested that the extent and rate of degra- 
 dation observed on the cotton fabric after 
 
 [12] 
 
0.650 
 
 0.600 
 
 e 
 
 0.550 
 
 
 cd 
 
 
 ^ 
 
 
 W 
 
 
 r£3 
 
 
 r-l 
 
 
 
 0.500 
 
 4J 
 
 
 M 
 
 
 C 
 
 
 <U 
 
 
 H 
 
 
 4J 
 
 
 CO 
 
 
 
 0.450 
 
 c 
 
 
 •H 
 
 
 8 
 
 
 u 
 
 
 (A 
 
 
 0.400 
 
 0.350- 
 
 0.300- 
 
 Exposure location: 
 
 California 
 
 X X 
 
 Colorado 
 
 — o 
 
 Nevada 
 
 X---X 
 
 New Mexico 
 
 © — © 
 
 Oregon 
 
 0--0 
 
 Utah 
 
 • • 
 
 10 
 
 15 
 
 20 
 
 25 
 
 30 
 
 Cellulose Fluidity (Rhes) 
 
 Fig. 1. Relationship of decrease in breaking strength to increase in cellulose fluidity for 
 cotton fabrics exposed outdoors for a total of 128 days. The increase was greatest in California 
 and Oregon, smallest in New Mexico. 
 
 128 days of exposure at Colorado, New 
 Mexico, and Utah was somewhat less than 
 might have been predicted from the 
 literature. 
 
 It is not possible to say exactly what 
 factors contributed to severe degradation 
 of the cotton at some exposure locations 
 and the relatively mild degradation at 
 others. However, the data available sug- 
 
 gest some possibilities. The strength- 
 fluidity relationships of the exposed sam- 
 ples (figure 1) suggests that the deteriora- 
 tion was due chiefly to photochemical 
 and not biological action because a de- 
 crease in strength was generally associ- 
 ated with an increase in fluidity. Ward 
 (1955) stated that high strength loss at- 
 tended by a marked increase in fluidity 
 
 [13 
 
indicates photochemical action and that 
 biological attack results in large losses in 
 strength and small increases in fluidity. 
 
 The pH values are another indication 
 that biological attack was not a major 
 cause of degradation. When strength and/ 
 or fluidity measurements indicated degra- 
 dation of the exposed samples, the pH 
 value was low. Studies on raw cotton have 
 indicated that microbiological growth is 
 associated with high pH values (Marsh et 
 al, 1951). 
 
 While degradation appears to be caused 
 by photochemical action, the regression 
 of fluidity upon hours of sunshine was 
 not found to be significant. Differences 
 in relative humidity among the locations 
 during exposure may be one factor that 
 could affect the rate of photochemical 
 action. Several authors have reported that 
 the photochemical degradation of textiles 
 is greater in moist air than in dry air 
 (Egerton, 1947; Egerton et al, 1962 and 
 1963; and Singleton et al, 1965). Data 
 on the relative humidity are not available 
 for all locations; however, U. S. climato- 
 logical records (U. S. Weather Bureau, 
 1960) give relative humidity values for 
 stations that may be used to indicate the 
 humidity at the locations during exposure 
 (table 9A). Using these data the regression 
 of fluidity upon relative humidity was 
 highly significant, and in the multiple re- 
 gression of fluidity upon relative humidity 
 and sunshine the addition of sunshine 
 made a difference which was significant 
 at the 0.01 level (tables 10A, 11 A). These 
 regressions thus provide statistical evi- 
 dence in support of the belief that both 
 relative humidity and hours of sunshine 
 affected the increase in cellulose fluidity 
 of the exposed samples. If solar radiation 
 values were available in place of hours of 
 sunshine a better correlation between 
 light and degradation may have been 
 found. 
 
 Traces of air pollutants in the atmos- 
 phere may have been another factor con- 
 tributing to the degradation of the ex- 
 posed fabrics. The pH values of the water 
 extract were lowest for samples showing 
 the greatest amount of degradation (table 
 1). The decrease in the pH of the water 
 extract may have resulted from acid or 
 
 acid-forming substances in the atmos- 
 phere being deposited on the fabric. The 
 hydrolysis of the cotton by the acid would 
 result in lowered breaking strength and 
 increased fluidity. Acidic constituents in 
 the atmosphere behave as aerosols and 
 may be deposited on exposed fabric when 
 precipitation (rain, fog, or dew) forms 
 around the particles and conducts them 
 to the fabric (Howard and McCord, 1960). 
 Gravity, electrostatic attraction, and di- 
 rect interception may also result in depo- 
 sition of the particles on the fabric. 
 
 Undoubtedly a complex combination 
 of climatic and environmental factors re- 
 sulted in the degradation of the exposed 
 samples. The results of the outdoor expo- 
 sure of these fabrics indicate the wide 
 variation in degree and rate of degrada- 
 tion that may occur from outdoor expo- 
 sure in different locations. 
 
 Laboratory Exposures A 
 
 Mean values for the laboratory measure- 
 ments done on the fabric made from 
 Acala 4-42 fiber after 300, 600, and 900 
 hours of exposure in the Fade-Ometer, 
 Weather-Ometer, and oven are given in 
 table 3. Exposure of the fabric in the 
 Fade-Ometer and Weather-Ometer re- 
 sulted in similar increases in cellulose 
 fluidity. After 900 hours of exposure the 
 increase in fluidity was 7.95 rhes for fab- 
 rics exposed in the Fade-Ometer and 8.81 
 rhes for those exposed in the Weather- 
 Ometer. Exposure of the samples in the 
 oven at 145°F did not result in any ap- 
 preciable change in fluiditv at the end of 
 the exposure period. 
 
 After 900 hours of exposure in the 
 Fade-Ometer the fabric lost 37 per cent 
 in breaking strength compared to a loss 
 of 12 per cent for samples exposed in the 
 Weather-Ometer for the same number of 
 hours. Exposure in the oven did not cause 
 any change in the strength of the fabric. 
 Decreases in elongation values of the 
 samples occurred only after exposure in 
 the Fade-Ometer. 
 
 Laboratory Exposures B 
 Light 
 
 Exposure in the Fade-Ometer of the fab- 
 rics made from Acala 4-42 and Pima S-l 
 
 [14] 
 
TABLE 3. Laboratory Exposures A: Mean Laboratory Measurements and 
 
 Standard Deviations. 
 
 Type of exposure 
 
 Exposure 
 
 Cellulose fluidity 
 
 Breaking strength 
 
 Elongation 
 
 Unexposed 
 
 Light 
 
 (Fade-Ometer) 
 
 Weathering 
 
 (Weather-Ometer) 
 
 Heat 
 
 (Oven) 
 
 hours 
 
 
 
 300 
 600 
 900 
 
 300 
 600 
 900 
 
 300 
 600 
 900 
 
 rhes 
 Mean S.D. 
 
 3.13 0.86 
 
 6.68 
 8.40 
 11.08 
 
 6.87 
 10.28 
 11.94 
 
 3.58 
 3.24 
 4.36 
 
 lb/yarn 
 Mean S.D. 
 
 541 
 0.487 
 0.427 
 
 0.674 
 0.623 
 0.599 
 
 0.707 
 0.700 
 
 0.694 
 
 054 
 
 055 
 0.027 
 0.073 
 
 0.039 
 0.048 
 0.030 
 
 040 
 0.033 
 042 
 
 inch 
 Mean S.D. 
 
 35 
 
 0.29 
 0.26 
 26 
 
 0.34 
 0.36 
 35 
 
 0.37 
 0.36 
 0.34 
 
 0.01 
 
 0.01 
 0.02 
 0.03 
 
 02 
 0.05 
 0.02 
 
 0.02 
 02 
 0.03 
 
 * Standard deviations are reported only for control. Fluidity was measured on two specimens for all other samples 
 and readings were less than ± 1 rhes of each other. 
 
 cotton fiber for 900 hours resulted in sub- 
 stantial gains in cellulose fluidity (table 4). 
 After 900 hours of exposure to light, the 
 Acala 4-42 fabric was found to have a 
 fluidity value of slightly over 13 rhes and 
 the Pima fabric value was approximated 
 12 rhes; a gain of approximately 9 and 10 
 rhes, respectively. While the Pima had a 
 greater percentage change in fluiditv, it 
 initially had a lower value and the rate of 
 change appeared to be similar for both 
 fabrics. For both fabrics there was no 
 apparent decrease in rate of change as 
 length of exposure increased. 
 
 The breaking strength of the fabrics 
 was reduced by exposure in the Fade- 
 
 Ometer — approximately 50 per cent for 
 the Acala fabric and 39 per cent for the 
 Pima after 900 hours. For both fabrics 
 the greatest reduction in strength oc- 
 curred during the first 300 hours of ex- 
 posure, and thereafter the rate of loss 
 decreased and was similar for both fab- 
 rics. Elongation of both fabrics was re- 
 duced in a similar manner bv exposure. 
 
 Heat and humidity 
 
 Laboratory exposures of Acala and Pima 
 cotton fabrics for periods up to 1,200 
 hours to varying conditions of heat and 
 humidity showed no well-defined trend 
 of degradation (table 5). Onlv small 
 
 TABLE 4. Laboratory Exposures B: Mean Laboratory Measurements 
 and Standard Deviations After Exposure to Light. 
 
 Fabric 
 
 Exposure 
 
 Cellulose fluidity 
 
 Breaking strength 
 
 Elongation 
 
 
 hours 
 
 rhes 
 Mean S.D.* 
 
 lb/yarn 
 Mean S.D. 
 
 inch 
 Mean S.D. 
 
 Acala 4-42 
 
 
 
 3.72 0.75 
 
 0.737 0.037 
 
 0.48 05 
 
 
 300 
 
 9.16 
 
 0.556 011 
 
 33 03 
 
 
 600 
 
 9.58 
 
 479 0.033 
 
 31 0.02 
 
 
 900 
 
 13 12 
 
 0.364 0.037 
 
 0.30 00 
 
 PimaS-1 
 
 
 
 1.65 0.17 
 
 0.879 0.049 
 
 53 04 
 
 
 300 
 
 6.70 
 
 673 048 
 
 34 05 
 
 
 600 
 
 S.48 
 
 0.590 0.036 
 
 33 0.03 
 
 
 900 
 
 11.93 
 
 547 009 
 
 34 02 
 
 * Standard deviations are reported only for control. Fluidity was measured on two specimens for all other samples 
 and readings were less than ± 1 rhes of each other. 
 
 [15] 
 
TABLE 5. Laboratory Exposures B: Mean Laboratory Measurements After 
 Exposure to Heat and Humidity. 
 
 Fabric 
 
 Relative 
 humidity 
 
 Temperature 
 
 Exposure 
 
 Cellulose 
 fluidity 
 
 Breaking 
 strength 
 
 Elongation 
 
 
 per cent 
 
 degrees F 
 
 hours 
 
 rhes 
 
 lb/yarn 
 
 inch 
 
 Acala 4-42 
 
 45 
 
 70 
 
 
 300 
 
 3.72 
 3.64 
 
 0.737 
 0.734 
 
 0.48 
 0.51 
 
 
 
 
 600 
 
 3.82 
 
 0.726 
 
 44 
 
 
 
 
 900 
 
 3.84 
 
 0.679 
 
 0.40 
 
 
 
 
 1,200 
 
 3.79 
 
 0.712 
 
 0.43 
 
 
 
 105 
 
 300 
 
 3.86 
 
 0.712 
 
 0.51 
 
 
 
 
 600 
 
 4.33 
 
 0.712 
 
 0.51 
 
 
 
 
 900 
 
 4.03 
 
 0.707 
 
 0.41 
 
 
 
 
 1,200 
 
 3.18 
 
 693 
 
 40 
 
 
 
 145 
 
 300 
 
 3.92 
 
 0.729 
 
 0.46 
 
 
 
 
 600 
 
 3.96 
 
 0.721 
 
 0.44 
 
 
 
 
 900 
 
 4.36 
 
 0.714 
 
 0.42 
 
 
 
 
 1,200 
 
 4.64 
 
 0.697 
 
 0.39 
 
 
 95 
 
 70 
 
 300 
 
 4.14 
 
 0.718 
 
 0.44 
 
 
 
 
 600 
 
 4.24 
 
 0.704 
 
 0.43 
 
 
 
 
 900 
 
 3.89 
 
 0.693 
 
 0.44 
 
 
 
 
 1,200 
 
 3.81 
 
 0.654 
 
 44 
 
 
 
 105 
 
 300 
 
 4.37 
 
 0.699 
 
 0.49 
 
 
 
 
 600 
 
 3.50 
 
 656 
 
 0.49 
 
 
 
 
 900 
 
 3.78 
 
 0.635 
 
 0.49 
 
 
 
 
 1,200 
 
 3 54 
 
 0.708 
 
 43 
 
 
 
 145 
 
 300 
 
 3.63 
 
 0.720 
 
 0.41 
 
 
 
 
 600 
 
 4.28 
 
 709 
 
 0.43 
 
 
 
 
 900 
 
 3.85 
 
 0.715 
 
 0.46 
 
 
 
 
 1,200 
 
 4.54 
 
 0.717 
 
 0.46 
 
 Pima S-l 
 
 
 
 
 
 1.65 
 
 0.879 
 
 0.53 
 
 
 45 
 
 70 
 
 300 
 
 1.82 
 
 883 
 
 0.58 
 
 
 
 
 600 
 
 1 70 
 
 0.826 
 
 0.58 
 
 
 
 
 900 
 
 1.62 
 
 0.868 
 
 0.53 
 
 
 
 
 1,200 
 
 1.58 
 
 0.885 
 
 0.56 
 
 
 
 105 
 
 300 
 
 1.71 
 
 0.840 
 
 0.59 
 
 
 
 
 600 
 
 1.93 
 
 0.818 
 
 0.59 
 
 
 
 
 900 
 
 1.76 
 
 0.832 
 
 61 
 
 
 
 
 1,200 
 
 1.67 
 
 0.863 
 
 0.48 
 
 
 
 145 
 
 300 
 
 1 84 
 
 0.830 
 
 0.53 
 
 
 
 
 600 
 
 2.12 
 
 0.851 
 
 0.49 
 
 
 
 
 900 
 
 1.91 
 
 0.875 
 
 0.56 
 
 
 
 
 1,200 
 
 2.08 
 
 0.833 
 
 0.51 
 
 
 95 
 
 70 
 
 300 
 
 1.78 
 
 0.868 
 
 0.56 
 
 
 
 
 600 
 
 1.71 
 
 0.818 
 
 0.56 
 
 
 
 
 900 
 
 1.59 
 
 0.846 
 
 0.50 
 
 
 
 
 1,200 
 
 1.76 
 
 0.833 
 
 0.49 
 
 
 
 105 
 
 300 
 
 1.84 
 
 812 
 
 0.59 
 
 
 
 
 600 
 
 1.62 
 
 0.822 
 
 0.62 
 
 
 
 
 900 
 
 1.94 
 
 0.837 
 
 0.64 
 
 
 
 
 1,200 
 
 1.65 
 
 0.836 
 
 0.56 
 
 
 
 145 
 
 300 
 
 1.89 
 
 0.860 
 
 0.52 
 
 
 
 
 600 
 
 1.82 
 
 0.859 
 
 0.53 
 
 
 
 
 900 
 
 1.82 
 
 0.853 
 
 0.59 
 
 
 
 
 1,200 
 
 2.22 
 
 0.846 
 
 0.56 
 
 changes in cellulose fluidity, and break- ing from 70° to 145 °F at 45 per cent and 
 
 ing strength and elongation, were found 95 per cent RH. 
 
 for samples exposed to temperatures rang- Other studies showing effects of tern- 
 
 [16] 
 
peratures and humidity in the range used 
 in this work over prolonged periods of 
 time appear to be lacking. While cotton 
 is fairly resistant to moderate heat (Ward, 
 1955), Hessler and Workman (1959) have 
 shown that degradation occurred when 
 cotton containing 4 per cent moisture 
 was heated for 20 minutes in a forced- 
 draft oven at 90 °C. Many other workers, 
 using more severe conditions, have sub- 
 stantiated the degrading action of heat on 
 cellulose. The presence of moisture dur- 
 ing heating has been shown to increase 
 degradation with increasing time and/or 
 temperature (Orr et al., 1954, and Wieg- 
 erink, 1940). Thus it may be concluded 
 that the temperature and moisture condi- 
 tions used were not severe enough or long 
 enough to result in degradation in the 
 absence of light. 
 
 Ozone 
 
 Exposure of Acala 4-42 and Pima S-l 
 cotton fabrics to 0.5 ppm of ozone for 
 periods of 300, 600, 900, and 1,200 hours 
 had no appreciable effect upon values for 
 cellulose fluidity or breaking strength and 
 elongation (table 6). 
 
 Laboratory exposures of cotton to 
 ozone by other workers (Bogaty et al., 
 1952, and Doree and Healey, 1938) have 
 shown little action of dry ozone on dry 
 cellulose, but degradation occurred when 
 the moisture content of the cellulose was 
 high. At 70°F and 72 per cent RH, the 
 conditions during exposure of the fabric 
 to ozone in present study, the regain of 
 the samples would be approximately 9 
 
 per cent. Apparently under these condi- 
 tions, and in the absence of light, 50 
 pphm ozone has little degrading effect on 
 cellulose. 
 
 Air movement 
 
 Subjecting Acala 4-42 and Pima S-l cot- 
 ton fabrics to conditions simulating a 
 wind velocity of 40 miles per hour for 
 periods of 300, 600, and 900 hours seemed 
 to have no effect upon degradation as 
 evaluated by changes in cellulose fluidity, 
 breaking strength and elongation (table 7). 
 Few studies have been specifically con- 
 cerned with the effect of air movement 
 on the deterioration of fabrics, however 
 wind is mentioned as a component of 
 weather which causes damage to textiles 
 (Appleby, 1949; Bogaty et al, 1952; Bush, 
 1960). 
 
 Comparison of Laboratory 
 
 Exposures A and B 
 
 The only laboratory conditions that re- 
 sulted in degradation of the cotton fabrics 
 were exposure to the carbon-arc lamps of 
 the Fade-Ometer and Weather-Ometer. 
 Exposure to heat and humidity, ozone, 
 and air movement in the absence of light 
 for 900 or 1,200 hours did not result in 
 any appreciable change in cellulose fluid- 
 ity or breaking strength. No significant 
 differences were observed between the 
 rates of degradation or the relationship 
 between fluidity and strength changes for 
 the Acala 4-42 and Pima S-l cotton 
 fabrics. 
 
 TABLE 6. Laboratory Exposures B: Mean Laboratory Measurements 
 After Exposure to Ozone. 
 
 Fabric 
 
 Exposure 
 
 Cellulose fluidity 
 
 Breaking strength 
 
 Elongation 
 
 
 hours 
 
 rhes 
 
 lb/yam 
 
 inch 
 
 Acala 4-42 
 
 
 
 3.72 
 
 0.737 
 
 48 
 
 
 300 
 
 3.36 
 
 0.688 
 
 42 
 
 
 600 
 
 3.34 
 
 0.705 
 
 0.43 
 
 
 900 
 
 3.97 
 
 0.645 
 
 0.46 
 
 
 1,200 
 
 3.52 
 
 0.679 
 
 0.46 
 
 Pima S-l 
 
 
 
 1.65 
 
 0.879 
 
 0.53 
 
 
 300 
 
 1 59 
 
 0.826 
 
 51 
 
 
 600 
 
 1.84 
 
 0.830 
 
 57 
 
 
 900 
 
 1.74 
 
 0.786 
 
 0.54 
 
 
 1,200 
 
 1.86 
 
 0.849 
 
 54 
 
 [IV] 
 
TABLE 7. Laboratory Exposures B: Mean Laboratory Measurements 
 After Exposure to Air Movement. 
 
 Fabric 
 
 Exposure 
 
 Cellulose fluidity 
 
 Breaking strength 
 
 Elongation 
 
 
 hours 
 
 rhes 
 
 lb/yarn 
 
 inch 
 
 Acala4-42 
 
 
 
 3.72 
 
 0.737 
 
 0.48 
 
 
 300 
 
 3.91 
 
 0.720 
 
 0.38 
 
 
 600 
 
 3.65 
 
 0.765 
 
 0.38 
 
 
 900 
 
 3.65 
 
 0.765 
 
 0.40 
 
 PimaS-1 
 
 
 
 1.65 
 
 0.879 
 
 0.53 
 
 
 300 
 
 1.58 
 
 0.768 
 
 0.66 
 
 
 600 
 
 2.00 
 
 0.865 
 
 0.45 
 
 
 900 
 
 1.77 
 
 0.897 
 
 0.50 
 
 •H 
 •H 
 
 3 
 
 r-l 
 
 <U 
 w 
 o 
 
 300 
 
 600 
 
 900 
 
 HOURS OF EXPOSURE 
 Fig. 2. Relationship of increase in cellulose fluidity to hours of exposure for cotton fabrics 
 exposed in the laboratory to carbon-arc lamps. The rate of degradation of the Acala 4-42 
 fabric and Pima S-l fabric exposed in the Fade-Ometer was similar. The Acala 4-42 fabric 
 degraded more during Fade-Ometer Exposure B (continuous exposure) than Exposure A 
 (intermittent exposure). 
 
 [18] 
 
A comparison of cellulose fluidity val- 
 ues after exposure of Acala 4-42 cotton 
 fabric in Fade-Ometers indicates that the 
 fabric degraded more during Laboratory 
 Exposure B than during Exposure A (fig- 
 ure 2). In the "A" work the exposure was 
 intermittent, i.e. 4 hours of light followed 
 by 1 hour with no light, while in the 
 other exposure the carbon-arc lamp was 
 on continuously. These exposures were 
 made in different Fade-Ometers, at dif- 
 ferent times, and at different laboratories. 
 Any of these factors may have had an 
 effect on results. However, the differences 
 in degradation may indicate that continu- 
 ous exposure in the Fade-Ometer is more 
 deleterious than intermittent exposure. 
 
 The relationship between changes in 
 breaking strength and cellulose fluidity 
 for samples exposed to carbon-arc lamps 
 is shown in figure 3. Under the condi- 
 tions employed in this study, the pres- 
 ence of moisture during exposure to light 
 (Weather-Ometer) resulted in similar in- 
 creases in cellulose fluidity and less loss 
 in strength than exposure to light at rela- 
 tively low humidity conditions (Fade- 
 Ometer), especially during the first 600 
 hours of exposure. 
 
 Comparison of Outdoor and 
 Laboratory Exposures 
 
 In both outdoor and laboratory exposures 
 to light the presence of moisture tended 
 to result in a larger increase in fluidity with 
 a corresponding decrease in strength than 
 when exposures were made in a dry at- 
 mosphere. This is shown in figure 4 by 
 comparison of outdoor exposures in Cali- 
 fornia and Oregon (high humidity) with 
 exposure in New Mexico (low humiditv) 
 and laboratory exposure in the Weather- 
 Ometer (high humiditv) and Fade-Ometer 
 (low humidity). 
 
 The relationship between changes in 
 fluidity and breaking strength for cotton 
 degraded bv exposure to sunlight in drv 
 and moist air has been reported to be 
 linear with a rise of fluidity of 10 units 
 corresponding approximately to a loss of 
 strength of 20 per cent (Egerton, 1947). 
 Recently Egerton et al. (1962), have re- 
 ported that irradiation in the far ultra- 
 
 [ 
 
 violet (2537 A) in dry air produces a 
 larger loss in strength than irradiation in 
 moist air, the difference being greater for 
 short times of exposure. They found 
 changes in fluiditv were greater for ex- 
 posure in humid air than in drv air. Dur- 
 ing the outdoor exposures probably none 
 of the ultraviolet radiation reaching the 
 samples would have been in the range of 
 2600 A, as used by Egerton. Therefore, 
 it appears that irradiation of longer wave 
 length, as might reach the surface of the 
 earth, in moist and dry air results in 
 strength-fluiditv changes similar to those 
 reported by Egerton in the far ultraviolet. 
 Figure 4 illustrates that the points for 
 samples exposed under generally moist 
 conditions fall to the left of the line mark- 
 ing a change in fluidity of 10 units with a 
 decrease in strength of 20 per cent and 
 the points for fabrics exposed under drier 
 conditions fall to the right. 
 
 The proportionate differences between 
 increase in fluidity values and loss in 
 strength of samples exposed under condi- 
 tions of high and low humiditv may indi- 
 cate that these two types of exposure 
 resulted in different types of reactions. 
 An increase in cellulose fluidity indicates 
 that the cellulosic chains have become 
 shorter. This shortening of the chains, 
 along with a breakdown of the complex 
 fibrillate structure of the fiber, results in 
 changes in strength. If the degradation 
 occurs near the end of the cellulose chain, 
 there may be less increase in fluidity com- 
 pared to nonlocalized cleavage (Egerton 
 et al, 1962, and Goldthwait and Robin- 
 son, 1958). Therefore it appears that out- 
 door and laboratory exposure to light in 
 moist air resulted in nonlocalized degra- 
 dation while exposure in drier air resulted 
 in localized degradation of the cellulose 
 near the end of the chain. 
 
 The only laboratory exposures that re- 
 sulted in changes in breaking strength 
 and/or cellulose fluidity of the fabrics 
 were those exposed to the light of a car- 
 bon-arc lamp (tables 3 and 4). The changes 
 in fluidity of samples exposed outdoors at 
 California and Oregon for 32 days (ap- 
 proximately 12 to 14.5 rhes) were similar 
 to the changes observed for samples ex- 
 posed to carbon-arc lamps for 900 hours 
 
 19] 
 
C 
 
 C w 
 
 •H XI 
 
 CO v_x 
 
 0.8 
 
 0.7 
 
 0.6 
 
 0.5 
 
 0.4 
 
 0.3 
 
 0.2 
 
 0.1 
 
 Laboratory Exposure A 
 Q_Q Fade-Ometer Acala 4-42 fabric 
 X x Weather-Ometer Acala 4-42 fabric 
 
 Laboratory Exposure B 
 Fade-Ometer Acala 4-42 fabric 
 Fade-Ometer Pima S-l fabric 
 
 10 
 
 15 
 
 Cellulose Fluidity (Rhes) 
 Fig. 3. Relationship of decrease in breaking strength to increase in cellulose fluidity for 
 cotton fabrics exposed in the laboratory to carbon-arc lamps. Exposure to light in the Weather- 
 Ometer resulted in similar increases in cellulose fluidity but less loss in strength than exposure 
 in the Fade-Ometer to light. The relationship of strength to fluidity changes were similar for 
 the Acala 4-42 and Pima S-l fabrics. 
 
 (11 to 13 rhes). Samples exposed outdoors 
 at Colorado, Utah, and New Mexico for 
 128 days still had fluidity values less than 
 those observed for 900 hours of labora- 
 tory exposure to light. Changes in break- 
 ing strength of the outdoor and Fade- 
 Ometer exposed samples followed a pat- 
 tern similar to that described for cellulose 
 
 fluidity changes. Exposure in the Weather- 
 Ometer generally resulted in less loss in 
 strength than exposure outdoors at the 
 six locations. 
 
 Considering the relationship of fluidity- 
 strength changes (figure 4), it appears that 
 exposure in the Weather-Ometer gave 
 some indication of the rate of degrada- 
 
 20] 
 
30 
 
 
 1 1 
 
 
 
 1/ 1 
 
 25 
 
 
 
 • i 
 
 
 a 
 
 20 
 
 
 • / 
 
 □ 
 
 
 • California 
 
 15 
 
 
 / ® 
 ■ / 
 
 
 
 A Colorado 
 
 E Nevada 
 O New Mexico 
 T Oregon 
 x Utah 
 
 10 
 
 
 
 V 
 
 ■ Weather-Ometer Acala 4-42 *~ 
 v Fade-Ometer Acala 4-42 
 
 
 
 / v 
 
 
 
 ® Fade-Ometer Pima S-l 
 
 
 
 ' L o °® 
 
 
 
 
 5 
 
 ■ 
 
 / * ® v v 
 
 / A 
 
 /A O v 
 / A X 
 
 < 6 
 
 1 1 
 
 
 
 1 1 
 
 20 
 
 40 
 
 60 
 
 80 
 
 100 
 
 Percent loss in strength 
 
 Fig. 4. Relationship of increase in cellulose fluidity to percentage loss in breaking strength 
 for cotton fabrics exposed outdoors and in the laboratory. The points for samples exposed 
 under generally moist conditions fall to the left of the line (marking a change in fluidity of 10 
 units with a decrease in strength of 20 per cent) and the points for fabrics exposed under drier 
 conditions fall to the right. 
 
 tion that occurred during outdoor expo- 
 sure at the California and Oregon loca- 
 tions. In contrast, exposure in the Fade- 
 Ometer gave little indication of the rate 
 or amount of degradation resulting from 
 exposure at any of the locations, except 
 New Mexico. 
 
 It is apparent that rate and amount of 
 photo-degradation during outdoor expo- 
 
 [21 
 
 sure varies greatly among locations. 
 Among the many factors that may affect 
 the rate of degradation (temperature, 
 moisture, air currents, ozone), none was 
 found capable of reacting with cotton in 
 the absence of light in laboratory expo- 
 sures. It is probable that the interaction 
 of these factors during outdoor exposure 
 is complex. 
 
 ] 
 
LITERATURE CITED 
 
 American Association of Textile Chemists and Colorists 
 1960. Technical Manual. New York: Howes Publishing Co. 
 American Society for Testing Materials 
 
 1960. ASTM Standards on Textile Materials. Committee D-13. Philadelphia. 
 Appleby, D. K. 
 
 1949. The action of light on textile materials. American Dyestuff Reporter 38:149- 
 56; 189-92. 
 Bogaty, H., K. S. Campbell, and W. D. Appel 
 
 1952. The oxidation of cellulose by ozone in small concentrations. Textile Research 
 Jour. 22:81-83. 
 Bush, G. F. 
 
 1960. New artificial weathering methods — rubber, plastics and textiles. American 
 Dyestuff Reporter 49:64-70. 
 Cyrot, J. 
 
 1958. The effect of mercerization on cotton's resistance to microorganisms. Textile 
 Research Jour. 28:1048. 
 Doree, M. A., and A. C. Healey 
 
 1938. The action of ozone on cellulose and modified cellulose. Jour. Textile Inst. 
 29:T27-42. 
 Egerton, G. S. 
 
 1947. The action of light on dyed and undyed cotton. Jour. Soc. Dyers Colourists 
 
 63:161-71. 
 1949. The mechanism of the photochemical degradation of textile materials. Jour. 
 Soc. Dyers Colourists 65:764-80. 
 Egerton, G. S., E. Attle, and M. A. Rather 
 
 1962. Photochemistry of cellulose in the far ultra-violet. Nature 194:968-69. 
 Egerton, G. S., E. Attle, F. Guirguis, and M. A. Rather 
 
 1963. The action of far-ultraviolet radiation on cotton cellulose. Jour. Soc. Dyers 
 Colourists 79:49-55. 
 
 Fels, M. 
 
 1960. Weathering of textile yarns. Jour. Textile Inst. 51:P648-56. 
 Goldthwait, C. F., and H. M. Robinson 
 
 1958. Improved light and weather resistance of cotton resulting from mercerization. 
 Textile Research Jour. 28:120-26. 
 
 Hessler, L. E., and H. Workman 
 
 1959. Heat-induced chemical changes in cotton fiber. Textile Research Jour. 29: 
 487-92. 
 
 Howard, J. W., and F. A. McCord 
 
 1960. Cotton Quality Study IV: Resistance to weathering. Textile Research Jour. 
 30:75-117. 
 
 Marsh, P. B., L. R. Guthrie, and M. L. Butler 
 
 1951. The influence of weathering and of microorganisms on the aqueous-extract 
 pH of cotton fiber. Textile Research Jour. 21:565-79. 
 Orr, R. S., L. C. Weiss, G. C. Humphreys, T. Mares, and J. N. Grant 
 
 1954. Degradation of cotton fibers and yarns by heat and moisture. Textile Research 
 Jour. 24:399-406. 
 Phillips, G. O., and J. C. Arthur, Jr. 
 
 1964. Chemical effects of light on cotton cellulose and related compounds. Part II: 
 Photodegradation of cotton cellulose. Textile Research Jour. 34:572-80. 
 
 Pomroy, E. R., and H. T. Stevens 
 
 1964. The effects of weather on drapery lining fabrics in two geographic regions 
 Jour. Home Econ. 56:607-13. 
 
 [22] 
 
Race, E. 
 
 1949. Degradation of cotton during atmospheric exposure, particularly in industrial 
 regions. Jour. Soc. Dyers Colourists 65:56-63. 
 Robinson, H. M., and W. A. Reeves 
 
 1961. Survey of the effect of light on cotton and other cellulosic fibers. American 
 Dyestuff Reporter 50:17-31. 
 Singleton, R. W., R. K. Kunkel, and B. S. Sprague 
 
 1965. Factors influencing the evaluation of actinic degradation. Textile Research 
 Jour. 35:228-36. 
 U. S. Weather Bureau 
 
 1960. Local Climatological Data. U. S. Department of Commerce, Washington, D.C. 
 Ward, K. 
 
 1955. Chemistry and chemical technology of cotton. New York: Interscience Pub- 
 lishers, Inc. 
 Whittaker, CM. 
 
 1935. The effect of certain vat dyes on cellulose when exposed to light and atmos- 
 pheric influences. Jour. Soc. Dyers Colourists 51:117—26. 
 Wiegerink, J. R. 
 
 1940. Effects of drying conditions on properties of textile yarns. Textile Research 
 Jour. 10:493-509. 
 
 [23] 
 
APPENDIX 
 
 TABLE 1A. Summary of Weather Data Recorded at Exposure Locations 
 During Outdoor Exposures 
 
 Exposure 
 
 Temperatures 
 
 Precipitation 
 
 Wind speed 
 
 Sunshine 
 
 Period 
 
 Location 
 
 Minimum 
 <32°F 
 
 Maximum 
 
 >85°F 
 
 Trace or 
 more 
 
 >25 mph 
 
 
 
 California 
 
 days 
 
 hours 
 
 32 days (March-April) . . . 
 
 
 
 
 
 12 
 
 1 
 
 241 
 
 
 Colorado 
 
 25 
 
 
 
 12 
 
 4 
 
 311 
 
 
 Nevada 
 
 25 
 
 
 
 12 
 
 11 
 
 330 
 
 
 New Mexico 
 
 8 
 
 
 
 4 
 
 7 
 
 359 
 
 
 Oregon 
 
 8 
 
 
 
 23 
 
 
 
 113 
 
 
 Utah 
 
 11 
 
 
 
 9 
 
 4 
 
 333 
 
 64 days (March-May) .... 
 
 California 
 
 
 
 
 
 18 
 
 2 
 
 584 
 
 
 Colorado 
 
 34 
 
 
 
 24 
 
 6 
 
 578 
 
 
 Nevada 
 
 47 
 
 
 
 23 
 
 24 
 
 698 
 
 
 New Mexico 
 
 9 
 
 9 
 
 5 
 
 11 
 
 726 
 
 
 Oregon 
 
 10 
 
 
 
 49 
 
 
 
 252 
 
 
 Utah 
 
 15 
 
 3 
 
 25 
 
 7 
 
 650 
 
 96 days (March-June). . . . 
 
 California 
 
 
 
 1 
 
 22 
 
 2 
 
 971 
 
 
 Colorado 
 
 35 
 
 2 
 
 39 
 
 6 
 
 892 
 
 
 Nevada 
 
 54 
 
 8 
 
 27 
 
 36 
 
 1,121 
 
 
 New Mexico 
 
 9 
 
 36 
 
 12 
 
 16 
 
 1.125 
 
 
 Oregon 
 
 11 
 
 
 
 72 
 
 
 
 472 
 
 
 Utah 
 
 16 
 
 8 
 
 31 
 
 16 
 
 1,045 
 
 32 days (April-May) 
 
 California 
 
 
 
 
 
 7 
 
 1 
 
 343 
 
 
 Colorado 
 
 9 
 
 
 
 12 
 
 2 
 
 267 
 
 
 Nevada 
 
 22 
 
 
 
 11 
 
 13 
 
 368 
 
 
 New Mexico 
 
 1 
 
 9 
 
 1 
 
 4 
 
 367 
 
 
 Oregon 
 
 2 
 
 
 
 27 
 
 
 
 139 
 
 
 Utah 
 
 4 
 
 3 
 
 16 
 
 3 
 
 317 
 
 32 days (May-June) 
 
 California 
 
 
 
 1 
 
 3 
 
 
 
 387 
 
 
 Colorado 
 
 1 
 
 2 
 
 15 
 
 
 
 314 
 
 
 Nevada 
 
 7 
 
 8 
 
 4 
 
 12 
 
 423 
 
 
 New Mexico 
 
 
 
 27 
 
 7 
 
 5 
 
 419 
 
 
 Oregon 
 
 1 
 
 
 
 23 
 
 
 
 220 
 
 
 Utah 
 
 1 
 
 5 
 
 6 
 
 9 
 
 395 
 
 32 days (June-July) 
 
 California 
 
 
 
 1 
 
 
 
 
 
 297 
 
 
 Colorado 
 
 
 
 15 
 
 17 
 
 3 
 
 357 
 
 
 Nevada 
 
 1 
 
 29 
 
 5 
 
 11 
 
 456 
 
 
 New Mexico 
 
 
 
 33 
 
 9 
 
 5 
 
 407 
 
 
 Oregon 
 
 
 
 4 
 
 2 
 
 
 
 343 
 
 
 Utah 
 
 
 
 26 
 
 1 
 
 3 
 
 416 
 
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TABLE 8A. 32 Days (March-April) and 128 Days Outdoor Exposure: Mean 
 
 Laboratory Measurements and Standard Deviations for Breaking 
 
 Strength and Elongation, and Resistance to Abrasion. 
 
 
 
 
 
 
 
 Resistance to abrasion 
 
 Exposure 
 
 Breaking strength 
 
 elongation 
 
 Impeller tumble 
 method 
 
 Inflated diaphragm 
 method 
 
 Location 
 
 Period 
 
 Mean 
 
 S.D. 
 
 Mean 
 
 S.D. 
 
 Mean 
 
 S.D. 
 
 Mean 
 
 S.D. 
 
 
 days 
 
 32 
 128 
 
 32 
 128 
 
 32 
 128 
 
 32 
 128 
 
 32 
 128 
 
 32 
 128 
 
 lb/yarn 
 
 inch 
 
 per cent wt loss 
 
 no. cycles 
 
 California 
 
 Colorado 
 
 Nevada 
 
 0.545 
 0.278 
 0.598 
 0.522 
 0.545 
 0.257 
 0.600 
 0.459 
 0.599 
 0.350 
 0.618 
 0.579 
 
 0.021 
 0.008 
 0.042 
 0.014 
 0.054 
 012 
 0.026 
 0.023 
 0.025 
 0.023 
 0.024 
 0.022 
 
 0.30 
 18 
 0.25 
 0.24 
 0.32 
 0.18 
 0.30 
 0.27 
 0.30 
 25 
 0.30 
 0.32 
 
 01 
 0.02 
 01 
 0.01 
 0.03 
 01 
 00 
 01 
 0.02 
 02 
 01 
 01 
 
 12 
 28 
 12 
 14 
 11 
 30 
 10 
 15 
 11 
 22 
 10 
 13 
 
 1.1 
 2.7 
 4.2 
 1.7 
 7 
 2 
 1.0 
 2.4 
 1.8 
 1.8 
 1.7 
 0.6 
 
 93.4 
 
 42.1 
 133 . 1 
 108.4 
 111.2 
 
 47.2 
 101.2 
 
 84.0 
 114.6 
 
 58.8 
 110.7 
 
 98.3 
 
 18.9 
 4.2 
 23.6 
 19.4 
 15.6 
 7 5 
 22 8 
 
 Oregon 
 
 Utah 
 
 15.1 
 12.4 
 7.1 
 16 2 
 17.4 
 
 TABLE 9A. Relative Humidity Near Exposure Locations During 
 
 Outdoor Exposure 
 
 
 Station reporting 
 
 32-day period 
 
 Location 
 
 March-April 
 
 April-May 
 
 May-June 
 
 June-July 
 
 
 Oakland Airport 
 
 Denver Airport 
 
 Reno Airport 
 
 El Paso Airport 
 
 Salem Airport 
 
 Salt Lake City Airport 
 
 per cent RH (average) 
 
 California 
 
 72 
 50 
 57 
 28 
 82 
 63 
 
 69 
 39 
 50 
 20 
 
 82 
 48 
 
 70 
 46 
 40 
 20 
 81 
 44 
 
 71 
 
 Colorado 
 
 Nevada 
 
 New Mexico 
 
 45 
 36 
 
 27 
 
 Oregon 
 
 69 
 
 Utah 
 
 23 
 
 
 
 TABLE 10A. Multiple regression — Cellulose Fluidity Upon Relative 
 Humidity and Hours of Sunshine 
 
 Source of variation 
 
 Sum of squares 
 
 Degrees of 
 freedom 
 
 Mean square 
 
 Relative humidity 
 
 167.7 
 60.4 
 228.1 
 139.5 
 367.6 
 
 1 
 
 1 
 
 20 
 22 
 
 
 Sunshine 
 
 Relative humidity and sunshine 
 
 60.4 
 
 Residual 
 
 6.98 
 
 Total 
 
 
 F = 8.65 
 
 Caluloee Fluidity - 0.221 IIH + 0.0295 Sunshine - 12.55. 
 
 [28] 
 
TABLE 11 A. Regression of Cellulose Fluidity Upon Relative Humidity 
 
 Source of variation 
 
 Sum of squares 
 
 Degrees of 
 freedom 
 
 Mean square 
 
 
 167.7 
 199.9 
 367.6 
 
 1 
 21 
 22 
 
 167.7 
 
 
 9.5 
 
 Total 
 
 
 
 F = 17.7 
 
 Cellulose Fluidity = 0.142 RH + 1.39. 
 
 To simplify this information, it is sometimes necessary to use trade names of prod- 
 ucts or equipment. No endorsement of named products is intended nor is criticism 
 implied of similar products not mentioned. 
 
 7im-6,'66(G936)J.F. 
 
THE GOOD EARTH 
 
 ... is the abundant earth. To achieve it, vast knowledge is needed 
 now — and more will be required as expanding populations continue to 
 make even greater demands upon the earth's resources. 
 
 How are scientists, researchers, and agriculturists developing and 
 implementing knowledge which will make the good earth flourish for 
 future generations? In part, the answer will be found in the many pub- 
 lications put out by the University of California's Division of Agricul- 
 tural Sciences. Among these publications are: 
 
 V 
 
 «$§$&• 
 
 the BULLETIN series . . . designed for an 
 audience of scientists, and for informed lay- 
 men interested in new research. 
 
 the CIRCULAR series 
 
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 popular audience, and offering extensive dis- m 
 cussions of some phase of an agricultural' 
 operation 
 
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