Vat Dye Continuous Processing Systems
topic
Vat dye continuous processing uses pad-steam or pad-roll systems applying reduced leuco vat dye under alkaline reducing conditions from sodium hydrosulphite or glucose-alkali systems, with steaming under exclusion of air maintaining the reduced leuco form during fixation before oxidation in aeration or hydrogen peroxide baths converts the leuco dye back to the insoluble vat form trapped within the fibre structure for superior wash fastness.
Role
Produces the highest wash fastness continuous dyeings on cotton fabrics for workwear, military, and technical textile applications requiring colour permanence under repeated industrial laundering, with vat dyeing complexity and cost being justified by the superior fastness performance that reactive dyes cannot match for the most demanding wash fastness specifications requiring fastness ratings above 4 to 5 on ISO 105 washing fastness scale.