Effects of Roller Ginning and Saw Ginning on Pima S-1 Cotton

A pilot plant evaluation was made to compare the effects of roller ginning and saw ginning on the fiber, yarn, and fabric properties and processing performance of Pima S-1 cotton. Combed and carded yarns made from roller- and saw-ginned cotton and sewing thread and fabric made from combed lots of each stock were evaluated. The fabrics were compared in the grey and after finishing (singeing, mercerization, scouring, bleaching, dyeing, and Sanforize treating). It was found that, within the limits of this study, the general processing efficiency of the roller-ginned cotton was better than that of the saw-ginned cotton. The method of ginning had no appreriable effect on the strength, uniformity, or elongation at break of combed yarns, but carded yarns spun from roller-ginned cotton were significantly stronger than those spun from saw-ginned stock. Combed yarns spun from the roller- ginned cotton were better in appearance than those spun from the saw-ginned stock. There were no significant differences in the physical properties of sewing thread pro duced from combed saw- or roller-ginned cotton. Fabrics produced from combed cotton ginned by both methods were approximately equal in tearing strength, but the saw-ginned cotton produced fabric that, in some cases, had a lower elongation and breaking strength. There were no significant differences in abrasion resistance between the fabrics before finishing, but the results for abrasion resistance of the finished fabrics were inconclusive. The fabric woven from the saw-ginned cotton contained consider ably more neps than that woven from the roller-ginned cotton. Since this type of cotton is generally used for the production of fine quality yarns and fabrics, it was concluded that saw-ginned extra long staple cottons would not be suitable for these uses. Also, due to the greater amount of waste during processing and poorer spinning performance of the saw-ginned cotton, processing costs would be higher and possibly offset any savings in ginning costs.