Change of UV Protection Efficiency of Apparel Fabrics by Washing -Effect of Fluorescent Whitening Agent in Detergent-.

Fluorescent whitening agents (FWA) absorb UV-A and decrease the transmittance, resulting in the increase of the UV-A protection efficiency. In this research, the UV protection efficiency of FWA absorbed during washing was clarified. Twenty two cotton and polyester fabrics were washed with four types of powder detergents for ten times by Tergot-O-Meter, and UPF (UV-B protection index) and APE (UV-A protection index) were calculated. Concerning the cotton fabrics, FWA decreased the transmittance of UV-A and UV absorber decreased that of UV-B. All the cotton fabrics having no UV protection efficiency before washing showed enough efficiency after five times washing except shirting (kanakin in Japanese). Kanakin was the only one cotton fabric which did not show enough efficiency after ten times washing. These results were also confirmed by an automatic washing machine. For the protection of photoallergy, it is advisable to wash cotton fabrics with detergent containing FWA and UV absorber before wearing. [ABSTRACT FROM AUTHOR]