PROCEDURE:

Thirty-one bales of Texas upland cotton were selected in a manner to ensure nine groupings of fibers with different values for fiber length and micronaire. Sampling strata and the resulting number of bales in each stratum are as follows:

The main cause of differing numbers of bales in each stratum (or cell) was the initial bale selection process being based on USDA classing data, but more exacting measurements taken at the International Textile Center shifted some of the bales to different categories. (Each bale was sampled at 10 layers throughout, with HVI measurements being done on each layer. Each measurement consisted of 4 replications of micronaire and 10 replications of length and strength.)

In addition to the Texas bales, 6 representative, high-quality bales were selected from other regions of the U.S. cotton belt: 3 bales from the Delta and 3 from California. Thus, all 6 of these bales fell into the long length category and care was taken not to get micronaire values higher than 4.90 from the Delta. The California cottons were all high-quality Acala varieties. The purpose of these 6 cottons, all of which are deemed appropriate for use on ring spinning systems, was to provide a better frame of reference for evaluating the performance of the Texas cottons.

A statistical summary of the HVI fiber data for all 37 bales used in the study is given in Table 1.

Table 1: Summary of main HVI fiber properties of the 37 bales

Preliminary experiments were done to evaluate the spin-ability limits of a representative Texas bale from each sampling strata. These experiments enabled an efficient selection of yarn sizes to make in the larger experimental design. Results from this made it clear that the compact spinning technology would open the ring spinning to cottons that are not generally considered suitable for this process. Indeed, all of the test cottons could be taken far beyond typical spin-ability limits on a conventional ring spinning system.

The experimental procedure used on all 37 cotton bales is outlined in Figure 2. The yarn sizes for each length group were chosen to enable useful comparisons between the conventional and compact yarns.