Improving the Dye Coverage of Immature Cotton Fibres by Treatment with Chitosan

A study has been made of the sorption by cotton of chitosan (a partially deacetylated poly(N-acetyl-D-glucosamine)) which had been applied to fabric by pad and exhaust methods. Chitosan pretreatment increases the exhaustion of direct dyes and is also very effective in eliminating differences in colour between dyed immature and mature cotton fibres. Some reduction in dye fastness results from the chitosan pretreatment when the dyeings are aftertreated with a conventional cationic fixing agent. However, much higher levels of fastness are obtained by aftertreatment with fibre-reactive quaternary ammonium compounds; in general, these compounds produce dyeings of similar fastness properties on both untreated and chitosan-treated cotton.