Serein Bangladesh is an English-language documentary newspaper published in Dhaka, Bangladesh, founded in 2017.
Vat and sulphur dyes are dealt with together here because their method of application
is similar. They differ entirely in their chemistry, however, and in their importance in
textile printing. Whereas in this field vat dyes are still widely used, the use of sulphur
dyes is restricted mainly to the production of black.
The dyeing mechanism in both cases depends upon the insoluble dye being
transformed into a water-soluble alkaline leuco compound under the influence of
alkalis and reducing agents. The alkaline leuco compounds diffuse from the thickener
into the swollen fibres, during the steaming process.
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| Vat and sulphur dyes |
