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Recent cotton processing studies conducted by Textile Research Institute have demonstrated that the presence of a large number of short fibers in cotton causes appreciable increases in processing wastes, excessively uneven rovings and yarns, less efficient spinning, and weaker yarns than would otherwise be expected. The present paper outlines various methods of measuring fiber length distribution and of indicating excessive quantities of short fibers in the sample.Four case histories demonstrating the inferior quality of cottons containing excessive quantities of short fibers are described. These show the effects of improper drying prior to ginning, overprocessing during cleaning, and microbiological attack (cavitoma).In all cases the importance of fiber length distribution as a cotton quality factor is emphasized.COTTON fiber length has been recognized as a quality factor for so long, and given so much attention in the past, that textile technologists are apt to assume that knowledge of this subject is complete. Present measures of fiber length are believed to provide indexes precise enough to distinguish between samples with different processing behavior. When the length indexes fail to indicate the observed quality differences, other factors such as fineness, mechanical properties, the age of the cotton, and that convenient catchall, &dquo;character,&dquo; are usually blamed.Studies at Textile Research Institute of these &dquo;other&dquo; factors have brought to light several instances in which the differences in fiber length were clearly responsible for inferior processing and yarn quality. In some of these instances the conventional length indexes would not have indicated the inferior cotton quality experienced in the processing and laboratory tests. The purpose of this paper is to pass these observations on to cotton technologists who may find them helpful in meeting practical problems encountered in manufacture. After a few preliminary definitions four actual case histories will be described to emphasize the importance of fiber length distribution as a quality factor. Fiber Length CriteriaCotton fibers, as they grow on the cotton seed, are remarkably uniform in length, as indicated by the length array in Figure 1. This length is indicated by the classer's staple length, the upper-half mean length from the Fibrograph, and the upperquartile length from the fiber length array. All these measures give values which are about equal to the average length of fibers on the seed. These measures are very useful in processing since they indicate length of the longest fibers in the sample arriving at the mill. The roll settings in various drafting and combing operations all depend on the length of these longest fibers.The bale cotton, however, contains many more short fibers than the seed cotton because of the extensive fiber breakage occurring in ginning. The difference between seed cotton and bale cotton in this respect is also shown in Figure 1. The quantities of these short fibers are not indicated by the staple le...

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