INDIGO DYEING OF COTTON DENIM YARN - CORRELATING THEORY WITH PRACTICE

The previously reported correlations in indigo dyeing of cotton denim between distribution of indigo in the cross-section of denim yarn, colour yield and dyebath pH are reviewed. Statistical analysis reveals that even with the experimental uncertainty of the absolute pK(a) values associated with the ionisation of the reduced form of indigo, distribution of indigo in the denim yarn cross-section and the resulting colour yield still are strongly correlated with dyebath pH.