The effects of the single fiber property fiber fineness on the physical properties of single yarns, both coarse and fine and of varying twist, were investigated. To permit the study of fiber fineness while maintaining other important properties approximately constant, a special technique was used which controlled the length factor by reducing all the cottons to common quartile and mean lengths. The cottons selected—Seaberry Sea Island, Mesa Acala, Tanguis, and Rowden 41—B—represented extremes in fineness, ranging from 2.9 to 5.6 μg. per in., and had other important fiber properties approximately equal. The study showed mainly that a relationship exists between fiber fineness and the turns per inch required in a single yarn to obtain optimum yarnstrength benefits. Low-twist yarns decreased less rapidly in strength from maximum strength when made from fine than when made from coarse fibers. In contrast, high-twist yarns decreased more rapidly in strength when made from fine rather than when made from coarse fibers. Yarns made from coarse fibers required more twist to attain maximum yarn strength than those made from fine fibers. The study also revealed that fiber fineness does not materially affect yarn elongation. In addition, it was found that fiber fineness is a critical factor of roving twist.THAT a relationship exists between cotton fiber properties, both individually and collectively, and yarn and fabric properties has been known from practical experience since the days when the spainning wheel was the only yarn producer.The relationship of fiber properties to the yarn property skein strength has been confirmed by means of statistical methods by many investigators. By substituting in the equations derived by some of these investigators the values obtained by measurements of certain fiber properties, yarn skein strength can be predicted within practical limits. But even the most successful of these prediction formulas are inadequate when it is desired to determine the effect of individual fiber properties on spinning quality. For example, length and fineness are properties hitherto so closely correlated that it has not been possible to evaluate statistically the distinct effect of each on yarn properties. Moreover, the statistical approach attempts to rank the fiber properties in relation to yarn skein strength only, without attempting to explain any effects on single and plied yarns of varying twists, product uniformity, processing behavior, or fabric quality.

Research leading to the development of specialized fabrics for an agency of the Department of Defense is described. Requirements called for the fabrics to be highly resistant to the passage of water and air and to possess relatively high tensile and tear strength, yet to be light in weight. The effects of 7 types of fabric structure on the physical properties of the fabrics are discussed. Of the constructions tested, basket weaves offered an acceptable com promise among the properties desired, with a 2/2 basket being highly water resistant without any chemical treatment and a 3/3 basket being slightly less water resistant and slightly more tear resistant. Regardless of the weave, as the picks per inch were in creased, air and water resistance increased and tear strength decreased. Bleaching, mercerizing, and dyeing significantly decreased the tightness of the fabrics; however, application of a flame-retardant and water-repellent treatment almost restored the original resistance of the fabrics to the passage of water and air.

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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.

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