BLEACHING EFFICIENCY AND PHOTOSTABILITY OF WOOL, WOOL COTTON BLENDS AND ALL-COTTON FABRIC/

In a followup to an investigation of the bleaching of worsted challis by the Agricultural Research Service (ARS) two-step, single-bath seque ntial oxidative/reductive process (full bleaching), comparative bleach ing studies were carried out on another fabric type, woolen flannel. I n the new studies, fabric was bleached in the individual oxidative and reductive steps of full bleaching and results were compared to those from ARS- and traditional full bleaching and to those from conventiona l bleaching by alkaline hydrogen peroxide. Bleached fabrics were studi ed for photo-yellowing and phototendering following exposure to artifi cial sunlight. ARS and conventional peroxide bleaching produced the sa me levels of yellowness after photoexposure. After photoexposure, the loss in strength of the fabrics from the ARS process was substantially less than the loss in strength from conventional peroxide bleaching. In full bleaching-ARS or traditional the reductive step contributed to significant strength loss, which was compensated by the oxidative ste p. As seen for all-wool, the ARS process for bleaching of cotton/wool or 100% cotton fabrics gave equivalent whiteness and yellowness values to that achieved by conventional bleaching. The bleached 50/50 union cloth with worsted wool warp and cotton weft showed significant streng th loss when stressed in the warp direction while a 50/50 intimate yar n-blended fabric and a 100% cotton fabric showed no strength losses.