The Geometry of Plain and Rib Knit Cotton Fabrics and Its Relation to Shrinkage in Laundering

The geometry of six plain and six rib circular-knit cotton fabrics with three different finishes was studied. Data on both gray and finished fabrics for stitch length, diameter of yarn, and wale and course spacings were used in evaluating the equations derived by Peirce for length of yarn in one stitch and for weight per unit area. Measured stitch length agreed with that calculated from Peirce's formula, l = 2p + w + 5.94d, when a specific volume of 1.1 was as sumed for the yarn. When the measured value for the yarn diameter was used, the stitch length was given by l = 2p + w + 4.56d. Weight of the fabrics calculated by Peirce's formula showed good agreement with that obtained by weighing a known area. In laundering tests, it was found that the shrinkage of the yarn was negligible, usually less than 1% in the finished fabrics. Curves relating the wale and course spacings of the unlaundered gray fabrics conformed to no orderly pattern. The gray material shrank in length and stretched excessively in width. Wale spacings plotted vs. course spacings in the laundered gray and finished fabrics followed parabolic curves. The finished fabrics in which wale and course spac ings approximated the parabolic relationship of the laundered fabrics changed the least in the length and width dimensions. These were the tighter-knit fabrics of two of the finishes. On the other hand, the fabrics having the greatest knitting stiffness shrank the most in area.