What is "vat dye"

n. Any of a type of dye, many based on indigo, in which a soluble form is used to impregnate a fibre or fabric and is then converted to an insoluble form

n. a dye that is applied by reducing the dye to a base-soluble form, applying the dye, then regenerating the insoluble dye by oxidation in the material; used for dyeing cotton [syn: vat color]

Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. Almost any dye, including fiber- reactive dyes, direct dyes, and acid dyes, can be used in a vat dye. Cotton, wool, and other fibers can be all dyed with vat dyes. The original vat dye is indigo, once obtained from plants but now produced synthetically.