ABSTRACT
Wool is bleached to a good cream color. The brilliant whites achieved with cotton and synthetics cannot be approached with wool, and no attempt is made to do so. Fully bleached wool is slightly whiter than unbleached scoured cotton. Bleached wool is still produced as such in many countries, and bleaching together with other finishing processes is common. A wool fiber is a complex, composite structure consisting of a thin, hard outer cuticle or sheath with a high degree of cystine cross-linking, which is separated by the endocuticular layer from a microfibular cortex. Alkaline fiber damage shows itself in yellowing, loss of strength, a fall in abrasion resistance, and an increased tendency to felting. An alkaline scouring process not only yellows the fiber, but also enhances yellowing on subsequent bleaching. Less is known about the relationships which the above chemical parameters bear to physical damage caused by reductive bleaching.
