Results are reported of a pilot plant evaluation of Pima S-1 cotton using an Egyptian variety, Karnak, and an American-Egyptian variety, Pima 32, as controls. The three cottons were processed alike on conventional equipment into a range of relatively fine single- and 2-ply yarns. Certain organizational details were varied within limits to aid in the evalution of the processing performance of the three cottons, and to determine the contributions each cotton made toward product quality. Each cotton was divided into three lots which were carded at 4, 6, and 8 lb/hr, respectively. Each lot was then combed, with 15 and 18% noils being removed. Twist- strength relationships were determined by spinning the yarns with a range of twist multipliers from 3.00 to 4.00 in increments of 0.25; draft-strength relationships were determined by spinning the yarns with a range of drafts from 14 to 53, using the twist multiplier found previously to produce maximum strength. The effect of the method of creeling was determined by spinning the same yarn number from a series of hank rovings both single and double creeled. Evaluation was made of gain in strength of 2-ply over single yarns using the same twist multiplier in both single and ply yarns. Also, an assessment was made of the response of these three cottons to three conditions of mercerizing and to subsequent dyeing. An analysis was made of opening-, picking-, and carding-waste percentages and of the uniformity of slivers and yarns. Yarn quality was determined by measuring skein and single-strand strengths, elongation, and appearance, and from the coefficient of variation of the strength values and Uster uniformity tester measurements. It was found that, within the limits of this study, the general processing performance of the Pima S-1 was equal to that of the Karnak and Pima 32 cottons. Regardless of the organizational variables used in the evaluation, the Pima S-1 cotton produced yarns of better appearance and uniformity than did the other two cottons. Also, yarns made from Pima S-1 were stronger than those made from Karnak, and were generally equal in strength to yarns made from Pima 32. Double creel produced stronger and more uni form yarns than did single-creel spinning for all the cotton varieties tested. The per formance of Pima S-1 in 2-ply constructions was equal to that of the two control cottons. The general response of Pima S-1 to mercerizing and to subsequent dyeing was slightly better than that of the other cottons.

A method has been found to prepare bulk samples of wool fibers in such a way that reproducible compression tests may be performed upon them. An evaluation of the bulk compression characteristics of 29 widely different wool samples shows that compressive load, rather than resilience, serves to bring out differences among them. This finding suggests that quality differences among wools, as determined by handling, are related to differences in the wools' resistance to compression rather than to differences in compressional resilience. For these 29 wool samples there is an inverse relationship between compressive load and mean fiber diameter. Although this finding is in agreement with similar results re ported for cotton fibers, it conflicts with the predictions from a theoretical model that has been proposed to explain the compressional behavior of wool. The theoretical model, which was based on a consideration of bending forces only during compression, has been claimed to fit results found for 310 samples of Merino wool. There is, therefore, an implication either that there is a different dependency of resistance to compression on fiber diameter within a wool breed as compared to that among different breeds or that the proposed theory is inadequate. When the compressing piston size is varied at a constant sample size for a Targhee 60's wool card sliver, it is found that the effective volume of fibers being compressed is greater than the volume of fibers beneath the piston, probably because of fiber-to-fiber entanglements. The experimental results indicate that a constant area should be added to the compressing piston areas in order to achieve a constant compressive stress. This area increment is independent of sample diameter, providing the sample diameter is suf ficiently greater than that of the compressing piston, and this area increment decreases with increasing degree of compression.