The redox behaviour of CI Sulphur Black 1 ‐ a'basis for improved understanding of sulphur dyeing

The redox properties of Cl Sulphur Black 1 are studied by redox and potentiometric titration. The results permit a more detailed description of the dyestuff reduction at a molecular level. Dyeing experiments with selected reducing agents show that dyestuff reduction is important in order to obtain a certain colour depth. When tin(II) chloride or iron(II) triethanolamine are used as reducing agents, a maximum correlation between redox potential and observed colour depth can be derived and a redox potential for maximum dyestuff affinity can be determined.