Thesis Details

Thesis Title: Feasibility of wet-on-wet pad/batch dyeing of 50/50 polyester/rayon woven fabrics with reactive dyes to obtain level dyeing
Thesis Author: Steven Hensley
Abstract: Pad/batch dyeing is commonly used for the application of reactive dyes. In most plants, the dye solution is padded onto dry fabric in a wet-on-dry process. In a wet-onwet process, the dye solution is padded onto wet fabric directly after bleaching with no intermediate drying step. Elimination of the drying step before dye application in the wet-on-wet process lowers production costs. However, the wet-on-wet dyeing process is susceptible to shade tailing, a decrease in the shade depth along the length of the dyed fabric due to dyebath dilution. The feasibility of wet-on-wet pad/batch dyeing was evaluated in this research. The effect of the water content of the fabric entering the dye pad and the wet pickup in the dye pad on dyebath dilution was examined. The possibility of preventing dyebath dilution by altering the concentration of the dye solution used in dyebath reconstitution was also investigated. Quality of the dyed goods was examined based upon fabric lightfastness, washfastness, crockfastness, shade, and shade variability. Several conclusions were drawn from this research. Shade tailing was prevented in wet-on-wet pad/batch dyeing by modifying the concentration of the reconstitution stream. Shade variation of the wet-on-wet dyed goods was no worse than that of the wet-on-dry dyed goods. No difference was found between wet-on-wet and wet-on-dry dyed goods with respect to lightfastness, washfastness, or crockfastness properties.