Application of Natural and Synthetic Tanning agent and Cationic Compounds for Improvement of Wash Fastness of dyed Silk, Wool and Nylon with Acid Dyes

In this work, we studied and compared the effectiveness of three different aftertreatments including full backtan, syntan and syntan/cation process on improvement of wash fastness of three different acid dyes applied on wool, silk and nylon. The effectiveness of the aftertreatments were determined, according to the ISO 105CO6 wash test. The results showed that Aftertreatment with natural tannins gained the highest wash fastness improvement. Although treating dyed samples with syntan improved the wash fastness of dyes, subsequent application of cationic agent enhanced their wash fastness to a great extent. The highest improvement of wash fastness was achieved in the case of acid dye with larger molecular size (supermilling acid dye). In addition, aftertreatments was more effective on acid dye with more sulphonic groups (leveling acid dye) and therefore more solubility. Comparing the results for different fibers, we found that the highest wash fastness improvement was obtained in the case of nylon while aftertreatments on wool and silk were also effective, but to a lesser extent.