The quantitative comparison of wash fastness improvement of acid and direct dyes on wool using full backtan,syntan, and syntan/cation system

Natural tannin, synthetic tanning agent (syntan), and syntan/cationic agent were applied on wool fabric dyed with different acid and direct dyes to improve the wash fastness of dyes. In this study, a method for quantitative and exact assessment of dye removal after washing from dyed samples was used. Firstly, the optimum operating parameters for application of full backtan and syntan were determined. Then the dyed wool samples were aftertreated, using natural tannin, syntan, and syntan/cationic agent. It was found that all aftertreatments improved the wash fastness. However, aftertreatment with natural tannin improved wash fastness to the greatest extent. In the case of syntan, sequential application of cationic agent on syntaned fabric obtained further improvement in wash fastness.