Sulphur Dyes are still a very important part of the dyeing industry and play an important role in the denim industry. The environmental concerns both over the feedstock for the dyes and the actual process has led to some recent developments see Archroma for some insights which also contains a useful video on the process used to apply both for sulphur and for indigo. Denim plays a massive role in the volume for textiles produced worldwide. In terms of dye feedstock Archroma have introduced Earthcolours which are sulphur dyes based on waste from the food industry (possibly the nut industry).
This extract from Burkinshaw is an important part of this course.
The following a a whole chapter on dyeing with sulphur dyes which you should use for the application details and structure details that are given. The figures for volume usage are probably out of date. C. Senior Dyeing with Sulphur Dyes
The auxiliaries used in sulphur dyeing are discussed in more detail in this chapter Shore – Auxiliaries used in sulphur dyeing
This 1989 review of Sulphur dyes provides some useful information on the types of dye and the similarities with Vat dyes.