Unevenness in the Appearance of Spun Yarn

Abstract

Object: This article experimentally reviews the assumptions on theory and the theoretical equations presented in the previous instalments. It seeks to confirm the theories previously deduced and grasp the characteristics of apparent unevenness. The samples used are 30s spun rayon yarns.Results: 1. The over-level ratio introduced in part 1 will do as a measure, or yardstick, by which to indicate the perception of apparent unevenness.2. Apparent unevenness is characterized not by a certain level or expression, but by the curve of the over-level ratio proper.3. The theoretical equations derived in part 1 are practical.4. The value of the length distribution in an ideal yarn and the value of the length distribution in service yarn have similar density functions.5. Level, the number of uneven areas, and the relation between these two factors and length have been experimentally obtained. The mean length of uneven areas has been deduced.6. An apparent uneven area is determined by the over-level ratio of the area proper. It is not influenced by the unevenness of environs or by the dimensions of the uneven area, i.e., not by any disturbances.7. The over-level ratio which distinguishes an uneven area from an even area exists in each level. The value of this discrimination threshold range has been obtained.8. The theoretical equation of the total length of uneven areas on a black board, given in part 2, fits practical cases.