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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Prep on Pima Cotton Textile Quality

Authors
item Hughs, Sidney
item Owen, Charles - PIMA AZ

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 5, 2000
Publication Date: June 30, 2000

Interpretive Summary: Ginned Pima cotton that is classified by a certified cotton classer as having excessive preparation or roughness in appearance is subject to price discounts in the market place. How these price discounts reflect actual cotton fiber quality or utility in the textile mill is not well defined. Paired prep (designated as having excessive preparation) and non-prep bales swere obtained from the three major Pima cotton production areas to be tested in order to better define what fiber or textile quality factors the preparation designation defines. The goal was to obtain paired bales whose only significant difference was the preparation designation. However, some of the prep bales were significantly lower in micronaire and fiber strength than their paired non-prep bales. These bales were then processed into yarn and cloth and the yarn and cloth was evaluated for quality. Evaluation of yarn and cloth properties showed significant statistical differences between production areas, but the differences were attributed to micronaire and strength differences. Quality as expressed by the prep designation was not statistically significant relative to yarn and cloth quality. Further work needs to be done to clarify the effect of prep by repeating the test with a better effort to obtain bales of cotton with similar raw fiber properties, including strength and micronaire, for both the prep and non-prep bales.

Technical Abstract: The only reliable source of Pima cotton that is classed as having excessive preparation is cotton that has been ginned in a commercial gin plant and then given the preparation designation during the normal classing operation. Representative Pima cotton bales that were classed both preppy and non-prep were obtained from each of the three major Pima cotton production areas. The goal was to obtain pairs of bales from each of the three production areas whose only significant difference was the preparation designation. The goal was not completely met for micronaire, but other HVI properties were in the normal range. Data analysis showed that there were significant differences between growing areas, as might be expected, in most of the raw fiber properties measured for the six bales tested. When comparing raw fiber properties between paired bales from a given production area, the prep bales tended to be lower in strength, micronaire, grade, color, neps, and length. Evaluation of yarn and cloth properties also showed significant differences between production areas as would be expected due to the initial differences in raw fiber properties between production areas. This test indicates that there are small but significant differences in some yarn properties and dyeing performance when comparing prep and non-prep Pima cotton. Yarn made from Pima cotton classed as preppy was not as uniform as the yarn made from cotton that did not receive the preparation designation. Also, the preppy cotton resulted in dyed cloth that was significantly higher in white specks than cloth made from non-prep cotton. One factor that could have affected the quality of yarn and cloth, apart from the preparation designation, was the low micronaire cotton included in the test.

Last Modified: 11/22/2014
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