Aftertreatments of Sulfur Black 1 Dyed Cotton Fabric: Optimization of Process Parameters for Developing a Protective System to Improve Color Retention

Abstract

Sulfur dyed cellulosic goods exhibit limited wash fastness against oxidative laundering; particularly to washing powder formulations containing activated bleaches. This study presents a novel two-bath exhaust finishing process to improve the wash fastness of Sulfur Black 1 dyed cotton fabrics reduced with two different reducing agents—sodium sulfide and a commercial glucose-based Diresul reducing agent D. The finishing process involves sequential aftertreatments with a cationic fixative and synthetic tanning agent (syntan). A Box-Behnken design with three variables: concentrations of cationic fixative and syntan, and application temperature of syntan (at three different levels) was studied to understand the effects of these variables on the color retention of the dyed cotton fabrics. Color retention of the sulfur dyeings was improved using the newly developed finishing process.