T tology estimated that more than 1

. I Effect of OBAs and Repeated Launderings on UVR Transmission through Fabrics By Ying Zhou and Patricia Cox Crews, University of Nebraska-Lincoln he American Academy of Derma- T tology estimated that more than 1 million skin cancers will be diagnosed in the United States in 1996 and half of all new cancers diagnosed this year will be skin cancers. I The increasing incidence of skin cancer in the populations of the U.S., Canada, and Australia has prompted educational programs ABSTRACT The increasing incidence of skin cancer in the populations of Australia and North America provided the impetus for developing educational programs about the risks of sun exposure and for developing sunscreens and sun protective clothing. In an effort to develop better fabrics for sun protective clothing, scientists have completed many studies investigating various factors influencing ultraviolet radiation (UVR) transmission through fabrics. Little research, however, has focused on the effect of repeated home launderings on UVR transmission through fabrics. In this study, eight types of summer-weight fabrics were subjected to home launderings using detergents with and without an optical brightening agent (OBA). Results showed that OBAs used in laundering improved the UVRblocking ability of cotton fabrics and cottonlpolyester blend fabrics, but not fabrics comprised entirely of polyester and nylon. The implication of the study is that a UPF rating determined for a new cotton or polyesterlcotton blend fabric can not only be maintained, but can be significantly enhanced by repeated laundering of the garment in a detergent containing an OBA. KEY TERMS Laundering Optical Brightening Agent (OBA) Sun-Protective Clothing Utraviolet Protection Factor (UPF) Ultraviolet Radiation aimed at informing the public of the risks associated with sun exposure, development of improved sunscreens, and the development and marketing of sun protective clothing. In an effort to develop better fabrics for sun protective clothing, scientists have conducted numerous studies investigating factors influencing ultraviolet radiation (UVR) transmission through fabrics. Reinert et al. briefly summarized the findings of many of these studies in a recent article published in Textile Chemist and Colorist.2 Most previous studies focused on the influence of fiber content, weave structure, porosity, weight, color, and fabric hydration on the UVR transmission of fabrics. Little research has focused on the effect of optical brighteners applied during repeated home launderings on the sunblocking properties of fabrics. In a review of the literature, only two studies were found in which scientists examined the effect of laundering on the sunblocking properties of fabric^.^^^ No published work was found that examined the effect of optical brightener applied through repeated laundering on the UVR transmission through fabrics. Stanford, Georgouras, and Pailthorpe found that wash and wear in a lo-week user study caused a significant increase in ultraviolet protection factor (UPF) of knitted cotton t-~hirts.~ UPF is an estimation of the protection a fabric provides against the biologically active component of ultraviolet radiation. It is comparabie, but not identical, to SPF which is based on in vivo testing of sunscreens. Stanford et al. concluded that the UPF of a garment may improve with use, mainly because of fabric shrinkage which reduces fab- ric p~rosity.~ They also acknowledged that further research was required to determine the effect of wash and wear for periods longer than weeks because longer periods may cause thinning of fabrics leading to a reduction in UPF. Subsequently, Stanford, Georgouras, and Pailthorpe conducted a study to determine the effect of prolonged laundering (6 washes) on sunblocking proper tie^.^ They found that cotton jersey-knit t-shirt fabric exhibited a significant increase in sunblocking ability (SPF doubled) after the first wash, presumably due to fabric shrinkage, but found almost no further change after another 5 washes. They deemed to launderings to constitute the reasonable life expectancy of a laundered garment before wear and tear or the dictates of fashion demand its replace- ~nent. ~ They concluded that a new cotton fabric s sun protective factor (SPF) rating will hold for the expected life of a garment. This had important implications for the Australian/New Zealand Standard 499:1996-Sun Protective Clothing: Evaluation and Classification-because the standard includes a classification system for the purposes of labeling sun protective ~lothing.~ Another factor related to laundering is the effect of the detergent type (with and without optical brightener) on UVR transmission through fabrics. This factor was raised in discussions among members of the AATCC Committee RA6 while Crews (author) served as committee chair. AATCC Committee RA6 was formed to provide a forum where AATCC members with an interest in issues pertaining to sun protective clothing could meet and discuss them and subsequently the members decided to develop a method for evaluating UVR transmission through fabrics. Optical brightening agents (OBAs) are a common additive to home laundry detergent formulations where they enhance the ness of textiles by UV excitation and re-emission in the visible blue range of the electromagnetic spectrum. Because OBAs absorb radiation in the ultraviolet region, it was reasoned that laundering fabrics with a detergent containing an OBA might improve the sun blocking properties of fabrics or at least maintain a fabric s initial level of sun blocking properties over the course of repeated.~ November 1998 Textile Chemist and Colorist 19

washings and wearings. However, laundering trials would be required to demonstrate whether or not the presence of an OBA applied through home laundering would maintain a fabric s UV-blocking properties or enhance the UV-blocking ability of fabrics and if so by how much. Experimental Procedures Experimental Design This study was designed to determine whether or not the presence of an OBA in a laundry detergent applied through repeated home laundering would enhance the sun blocking properties of selected woven and knitted fabrics. The two independent variables were detergent type (with and without OBA) and number of launderings (,1,5,, 15, and ). The dependent variables were percent transmission and UPF. Two replications were completed for each fabric and detergent type. Fabric Eight fabric types commonly used in summer clothing were evaluated in this study. Fabric types included % cotton sheeting, % cotton broadcloth, % cotton jersey knit, / polyester/cotton, / polyester/cotton jersey knit, % polyester, % nylon, and % Supplex nylon (Table I). These types of fabric were selected to represent a range of lightweight woven and knitted fabrics and fiber types commonly used in summer clothing. Supplex nylon, marketed in sun protective clothing by several manufacturers, is made from heavily delustered microdenier fibers and possesses a cotton-like hand that is enhanced by finishing processes. The jersey knits are typical of those used in t-shirts. Laundering Procedures Fabrics samples were laundered and dried according to the AATCC guidelines for Standardization of Home Laundry Test Conditions using a Kenmore, heavy duty, 7 series, extra capacity, washer and dryer manufac- tured by Sears, Roebuck and Co. Fabric samples serving as controls were laundered up to times in AATCC 199 Standard Reference Detergent WOB (without optical brightener), whereas another set of fabric samples was laundered up to times in AATCC 199 Standard Reference Detergent, a home laundry detergent formulation containing an optical brightener. Sixty grams of AATCC detergent were added after the fabrics were placed in the washer, then the washer was filled to a medium water level of 17 1 gal. Fabrics were washed on a permanent press setting (-minute washing time) and warm (41 C) washing temperature. A ballast of % cotton sheeting (dummy load) was added to obtain a 1.8 o.lkg. wash load. Fabrics were tumble dried at a permanent press setting. The exhaust temperature was 145C by the middle to the end of the -minute drying cycle. Fabrics were dried for minutes, except for the fabric samples of % nylon, % polyester, and % Supplex nylon which were dried for only 15 minutes to prevent the fabrics composed entirely of synthetic fibers from overheating or overdrying. Following,1,5,,15, and launderings, five x specimens were cut from each fabric sample in preparation for UVR transmission measurements. UPF and Percent Transmission Measurements Percent transmission and UPF values were measured using a Cary UV-Visible spectrophotometer (model 911297) with an ultraviolet light source and an integrating sphere attachment to collect all the diffusely scattered light transmitted through a fabric. A Schott glass filter UG-11 was placed between the specimen and the integrating sphere to prevent artificially high values of transmittance in specimens containing an optical brightener. The scan speed was 9 nm/min and spectral bandwidth was 4. nm. The wavelength range was 29 to 9 nm. Procedures described in AustralianINew Zealand Standaid 499, Sun Protective Clothing-Evaluation and Classification were fol- wed.~ Four measurements were taken on each of four specimens from each fabric sample per replication following each laundry interval. Two measurements were made in the warp direction and two in the filling direction on each specimen and each measurement was made at a 9 degree angle to the previous measurement. Mean percent transmission was computed over the spectral range between 29 and 9 nm. Ultraviolet Protection Factor (UPF) software, OS2/Warp version, developed by Varian, automatically calculated mean UPF. Solar spectral irradiance measured in Melbourne was used in the equation for calculating UPF by the Varian software. UPF is defined as the ratio of the average effective UVR irradiance calculated for unprotected skin to the average effective UVR irra- diance calculated for skin protected by the test fabri~. ~ More specifically, 9 EEL XS, UPF = % =,,, xaa E E, xs, xta XAA 29 Eq. 1 where E, = erythemal spectral effectiveness, Sk = solar spectral irradiance in W.m-2.nm-1, T, = spectral transmittance of the specimen, AA = measured wavelength interval in nm, and A = wavelength of light in nm. The term UPF was chosen to distinguish it from the SPF scheme, which traditionally is used to describe the UV-blocking ability of sunscreen based on in vivo or human testing of sunscreens. Although a percent transmission measurement can be used to characterize a fabric s sunblocking abilities, percent transmission values do not reflect large variations in spectral effectiveness in causing biological damage-uvb is considerably more effective at causing biological damage than UVA. 6 Therefore, the UPF scheme weighs more heavily the UVB wavelengths in the calculation of sun Table 1. Construction Characteristics of Fabrics Fabric nylon (TF #61p Supplex nylon cotton (TF #5) cotton (TF #419) polyester (TF #76) / C/PET (TF#7429) % cotton / C/PET Weave Structure jersey knit jersey knit Thread CounVFabric Gauge (Per inch; w xf Iw x c) 51 x46 117x69 51 x 1 x 67 41 x1 x 42 6 x 8 6 x 8 Weight (odsq. yd.).7 2.6 5.6.4 5.2 4.4.5 4. Thickness (in. at.624 psi).12.6.14.7 Color natural afabrics with a TF style number were purchased from Testfabrics, Middlesex, N.J. Supplex nylon was supplied by Burlington Industries, Greensboro, N.C. Textile Chemist and Colorist ax) Vol., No. 71

.L - protection. Consequently, UPF is regarded as a more useful means to describe a fabric s sunblocking ability. Statistical Analysis The data for each fabric type were analyzed separately using General Linear Model Analysis of Variance procedures. The level of significance was.5 for all tests. Mean UPF values for each fabric type laundered with an optical brightener were compared to mean UPF values for each fabric type laundered without an optical brightener. Then, Fisher s LSD tests were conducted to compare the difference in mean UPF and mean percent transmission for each fabric type due to number of launderings. Results and Discussion Mean percent transmission and UPF values for each fabric type before laundering and after 1, 5,, 15, and launderings with and without an OBA are shown in Table 11. % Cotton Fabrics Results showed that mean UPF increased and mean percent transmission decreased significantly following repeated launderings using a detergent with OBA in all three of the cotton fabrics included in the study (Table I1 and Figs. 1, 2, and ). The cotton sheeting showed a tenfold increase in mean UPF following launderings with an OBA (UPF = 5.5 initially, before laun- dering, and mean UPF = 57.1 after launderings). The % cotton broadcloth and the % cotton jersey knit showed smaller, but still impressive, improvements in UPF values after launderings of about sixfold increases each. When there was no OBA in the detergent formulation used in the repeated launderings, changes in mean UPF for the woven cotton fabrics were small, whereas the mean UPF of the cotton knit doubled following launderings. The changes observed in UVR transmission as expressed by UPF are attributed to fabric shrinkage which, in turn, leads to reduced porosity of the fabrics. As expected, a larger amount of shrinkage occurred in the cotton knit than the woven fabrics. These findings differ somewhat from those of Stanford et al. who found that shrinkage in the first wash accounts for most of the increase in SPF associated with laundering of cotton jersey-knit t- shirts4 They found that SPF doubled following the first wash and that further change after another 5 washes was not significant. By contrast we found that UPF did not come close to doubling until the fifth wash. These differences in findings may be associated with differences in laundry conditions. Although top-loading washing machines were used in both studies, Stanford et al. used a colour-fast setting (water temperature was not specified), whereas a permanent press set- ting (warm water temperature) was used in this study.* Another, and perhaps more important, difference was in drying time. Stanford et al. tumble dried their cotton knits for 6 minutes, whereas cotton fabrics in this study were dried for only minutes after each wash.4 Results clearly showed that significant improvement in the UV-blocking properties of woven cotton fabrics requires that the fabrics be laundered repeatedly using a detergent containing an OBA. Repeated laundering alone does not cause sufficient shrinkage to significantly improve the sun-blocking properties of the woven cotton fabrics. The cotton fabrics enhanced sunblocking properties following repeated launderings with an OBA are attributed primarily to the high absorptive capacity of the cotton fiber which facilitates the buildup of optical brightener on cotton fabrics. The buildup may also be due to the cotton fiber s greater chemical affinity for the OBA used in the AATCC detergent formulation. The buildup of optical brightener on cotton fabrics increased with each laundering interval included in this study (Table I). Further testing would be required to determine whether or not the OBA buildup would eventually level off. It had not reached a plateau at the end of launderings, the maximum number of launderings evaluated in this study. Detergent Type Mean UPF No. of Launderings WOBB WOB 1 WOB 5 WOB WOB 15 WOB OBb OB 1 OB 5 OB OB 15 OB Table II. Mean UPF and Percent Transmission for all Fabrics % % % / Cotton Cotton Cotton / PET/Cotton % Sheeting Broadcloth Knit PET/Cotton Knit PET 5.6 6.5 6.9 7.1 7.4 7.7 5.5 8.1 18. 2.4 4.1 57.1 4. 4.7 4.7 4.6 4.6 4.7 4.2 5.6 9. 1. 17.6 22.1 6.5 9.5 11.1 11. 11.8 12. 6.7 11.9 19.8 26.2 2.5 8.4 15.1 17.6 1 19.8 1.8 14.8 19.2 22.2 2.1 26.5 26.5 12.8 18.6.8 24.1 24.8 26.4 12.7 21.I 26.4.9.7 5.7 15.1 16.1 18. 19.5..6 14.4 16. 18.1 19.6 19.9.9 % % Supplex Nylon Nylon 6.9 16. 6.7 17.4 7. 17.2 6.7 17. 7. 17.4 6.9 17.4 6.8 16.8 6.8 17.6 6.8 17.8 7.2 18. 7.2 18.8 7.5 19.1 Mean Percent Transmission WOB WOB 1 WOB 5 WOB WOB 15 WOB OB OB 1 OB 5 OB OB 15 OB 16.5 18.9 15.5 15. 14.6 14.1 18.9.9.7 1.9 1.5 1.2 24.7 22.7 22.9 2. 22.8 22.6 25. 16.5 8.1 5..6 2.8 17.6 12.8 11.2 11.1.6.2 17.1 8.5 4. 2.9 2.4 2. 11.2 9.9 9. 9.5 9. 11.2 8.5 6.4 5.7 4.9 4.8.2 7.4 6.7 6. 5.9 5.4.2 6. 4.6.8.5. 11. 11.1.1 9.6 9.2 11.7.9. 9. 17.8 9.1 17.9 8.5 17. 8.6 18. 8.6 17.4 8.5 17.7 8.5 18. 8.8 17.4 8.2 16.6 7.4 15.5 6.9 15.2 6.5 14.2 6.2 awob = AATCC 199 Standard Reference Detergent WOB (without optical brightener). bob = AATCC 199 Standard Reference Detergent with optical brightener. November 7998 a Textile Chemist and Colorist 21

Bo Bo r I - OB LL 11 U n o 5 15 5 15 Fig. 1. Mean UPF for % cotton sheeting after laundering. Fig. 2. Mean UPF for % cotton broadcloth and laundering. PolyesterlCotton Blend Fabrics Both the woven and knitted polyester/ cotton blend fabrics exhibited higher mean UPF values (15.1 and 12.8 respectively) before laundering than did the % cotton fabrics (UPF value ranged from 4.-6.5). This difference in fabric types is attributed to inherent fiber properties. Cellulose is known to be very transparent to UV radiation, whereas polyester inherently absorbs more radiation in the UVB region than does cellulose.2 The polyester component in the fabric blends significantly enhances their sunblocking properties. When the polyester/cotton blend knit was laundered using a detergent without OBA, the mean UPF value 6 doubled. When laundered repeatedly using a detergent with OBA, the mean UPF value tripled (Table I1 and Fig. 4). In fact, the mean UPF in the knitted fabric increased and percent transmission decreased significantly after only one laundering. These changes are probably due to the shrinkage of the knitted fabric. The woven fabric also exhibited an increase in sunblocking properties following repeated launderings in a detergent with OBA. The increase, however, was not as great as it was for the knit (Fig. 5). This difference is attributed to the poorer dimensional stability of knits, in general, compared to woven fabrics. Thus, the results of this experiment show that Bo both the presence of OBA in a detergent formulation and repeated launderings significantly improved the UV-blocking ability of the polyester/ cotton blend fabrics; the effect of number of launderings is more pronounced in the knitted fabrics, as expected. Nylon and Polyester Fabrics The mean UPF and mean percent transmission values of % nylon, % Supplex nylon and % polyester after laundering with and without an OBA are illustrated in Figs. 6,7, and 8. The % polyester fabric has a higher UPF value and lower percent transmission value compared to the cotton fabrics and to the conventional OB kw ll n m Fig.. Mean UPF for % cotton knit after laundering. Fig. 4. Mean UPF for / polyester/cotton after laundering. 22 Textile Chemist and Colorist Vol., No. 11

! -OB I lot Fig. 5. Mean UPF for / polyester/cotton knit after laundering. Fig. 6. Mean UPF for % polyester after laundering. nylon fabric. This is probably because polyester fabric absorbs more radiation in the UVB region of the electromagnetic spectrum and transmission in that region is weighed more heavily in the calculation of UPFe2 Supplex nylon fabric, which is made of microdenier fibers, starts with a much higher mean UPF and much lower mean percent transmission value compared to conventional % nylon and has a slightly higher UPF value than conventional polyester. Supplex nylon's better UV-blocking ability than conventional nylon is probably due to the fact that Supplex nylon is heavily delustered with TiOz which has high absorption of UV radiation. This factor coupled with the microfiber fabric's higher thread count and tighter weave structure are presumed to be the reasons for the Supplex nylon's higher UPF than the conventional nylon fabric (Table I). The sunblocking properties for Supplex nylon increased slightly during repeated launderings; however, the changes are minor (4.5 UPF, 42.6 %T) and probably have no practical significance (Table I1 and Fig. 8). Results show that neither laundering without nor with an OBA enhances the sun blocking properties of fabrics made of conventional nylon and polyester. The lack of improvement in sunblocking properties following repeated launderings is attributed to the excellent dimensional stability of these woven fabrics, coupled with their limited affinity for the OBA. Therefore, their absorption of the OBA is so poor that there is no buildup on the nylon and polyester fabrics during repeated launderings. Consequently, repeated launderings did not significantly influence the % nylon or polyester fabric's mean UPF nor percent transmission values. It is possible that if a detergent formulation containing OBAs with substantivity for polyester and nylon were used that nylon and Bo U. n w 1 I Fig. 7. Mean UPF for % nylon after laundering. Fig. 8. Mean UPF for % Supplex nylon after laundering. November 1998 (ID Textile Chemist and Colorist 2

polyester fabrics might exhibit increased sunblocking properties as did the cotton fabrics in this study. Conclusions Laundering clothing with detergents containing an OBA is an effective means for improving the UV-blocking ability of cotton fabrics and polyester/ cotton blend fabrics, but not % nylon and polyester fabrics. The implication of this finding is that the UPF rating for a cotton or polyester/cotton blend fabric can not only be maintained, but can be significantly enhanced by repeated laundering of the garment in a detergent containing an OBA. Furthermore, findings show that repeated home launderings (regardless of whether or not the detergent contains an OBA) does not reduce the UPF rating of a woven or knitted fabric of cotton, polyester, or nylon. On the contrary UPF ratings are enhanced or remain unchanged by repeated launderings up to times. These findings should be helpful to the Consumer Product Safety Commission and AATCC and ASTM committees currently discussing labeling considerations for sun protective fabrics and clothing. Acknowledgement This research was supported in part by funding from the University of Nebraska-Lincoln, Agricultural Research Division (journal series no. 12156), and an AATCC/HE Student Research Award. References 1. American Academy of Dermatology, Skin Savvy: Stop Skin Cancer Before It Stops You, *..1 web www.aad/org/skincancernews/skin Savvy/StopsCancer.html, 1997. 2. Reinert, G., et al., Textile Chemist and Colorist, Vol. 29, No. 12, December 1997, p6.. Stanford, D., K. Georgouras, andm. Pailthorpe, TheMedicalJournal ofaustralia,vol. 162,No. 8, August 1995, p422. 4. Stanford, D., K. Georgouras, and M. Pailthorpe, Journal of the European Academy of Dermatology and Venereology, Vol. 5, 1995, p28. 5. Joint Standards Australia/Standards New Zealand Committee TX/21, AS/NZS 499:1996, Sun Protective Clothing-Evaluation and Classification. 6. Gies, H. P., et al., Health Physic, Vol. 67, No. 2, February 1994, p11. Author s Address Patricia Crews, University of Nebraska- Lincoln, P.O. Box 882, Lincoln, Nebr. 6 8 5 8-82 ; telephone 2-4 7 2-642; fax 2-472-6; e-mail pcrews @unl. edu. AATCC s 1999 BUYER S GUIDE AATCC is now compiling product information for its 1999 Buyer s Guide to be published in July. And we d like to add your company to the long list of producers and supplies already in it. Used worldwide, it is one of the most trusted source books in the textile wet processing industry. It covers: Dyes and Pigments Basic listing fee (includes 12 products) is $1 Additional product listings are $8 each (no limit). Chemical Specialties Basic listing fee (includes 12 products) is $1 Additionai product listings are $ each (no limit). Machinery, Equipment, and Supplies Basic listing fee (includes 12 products) is $1 Additional product listings are $ each (no limit). Business Cards Listing fee is $ and must be prepaid. AATCC accepts MasterCard. Visa. and American Express. To list your products or services in the 1999 Buyer s Guide contact: Lorraine Blanton AATCC P.O. Box 122 15 Research Triangle Park, NC 2779 Tel: 9 19-549-8 14 1 Fax: 9 19-549-89 E-Mail: blantonl@aatcc.org 24 Textile Chemist and Colorist cco Vol., No. 11