Improvement of Luster of Cotton

Anhydrous ethylamine and solutions of sodium hydroxide both affect the luster of cotton yarns in the same direction as well as having similar effects on properties which indicate de crease of crystallinity, or increase of accessibility of the cellulose. However, the extent of the effect is less for ethylamine, under the conditions examined, with one exception. When the cotton yarn is held at nearly constant length by wrapping on plates, with minimum possibility of mechanical action, the ethylamine treatment has more effect on moisture sorption, though less on luster, than the relatively low degree of mercerization obtained on plates. Tension or control of length is required to produce luster; treatment by either ethylamine or sodium hydroxide solution without tension decreases the luster. Luster is increased more by mercerizing after the ethylamine treatment than by the ethylamine treatment after merceriz ing, holding the yarn at original length. The stretching of the yarn, which is made possible by a swelling treatment, and the improvement of fiber roundness are more important for high luster than the degree of change of crystallinity of the cellulose. Thus, measures of accessibility, such as "barium number," do not indicate changes in luster primarily, but only indirectly and in limited ranges in which there is definite stretching of the yarn and with the important con dition that final yarn length is constant in the group being compared. In these special cases the accessibility measure can indicate the degree of action of the swelling agent and can parallel the effect on luster.