Abstract:

A new idea was investigated in this study wherein the use of coagulants was assessed in the wash-off process to simultaneously remove unfixed reactive dyes from fabrics and washoff liquor. At the end of dark shade dyeing (5% owf) with C.I. Reactive Yellow 145, C.I. Reactive Red 194, and C.I. Reactive Black 5, fabrics were subjected to both conventional and new wash-off methods, and comparisons were made. The effectiveness of coagulant wash-off was evaluated in terms of the change in shade, wash fastness, rubbing properties, and colour difference values (ΔL*,ΔC*, Δh* & ΔE*). The colour removal efficiency (%) of liquor was considered as indicative of the removal of unfixed dyes from the fabric. Overall results have shown that the use of alum and MgCl2 coagulants during the wash-off process can achieve up to an 87% reduction in the colour of wash-off liquor, without compromising the colour properties of the dyed substrate.