Investigation into the Use of Gelatin as a Buffer in the Dyeing of Wool with Indigo

Abstract

The effect of varying gelatin concentration and temperature on the levelness of wool dyed with 2.0% o.m.f. indigo for various time periods was investigated. The degree of levelness was measured in terms of (RUI)Cvalues. (RUI)Cstands for corrected relative unlevelness index as reported in the work of Chonget al.[1]. The colour fastness to washing of the indigo-dyed wool using gelatin as a buffer was also determined.Gelatin, used as a buffer, potentially maintained the dyebath pH at a constant value of 10 which consequently reduced the colour variations between dyeings. The levelness of dyeing and depth of shade was found to be unaffected by varying concentrations of gelatin. While longer dyeing times resulted in higher degree of levelness and enhanced shade depths, higher dyeing temperatures did not favour the dyeing of wool with indigo, in that lower shade depths and reduced levelness were achieved. Dyeings of excellent wash fastness and dry and wet rubbing fastness were obtained.