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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. The original vat dye is indigo , once obtained only from plants but now often produced synthetically.
Once the dye liquor has been made in the front compartment, the dye solution will gradually move from the front compartment into the main dye vat. The fabric is made into a number of loops by sewing the ends together. These loops are equal in length. The fabric is looped over the two wheels that are located at the top of the dye vat.
Indigo dye is an organic compound with a distinctive blue color. Indigo is a natural dye extracted from the leaves of some plants of the Indigofera genus, in particular Indigofera tinctoria . Dye-bearing Indigofera plants were commonly grown and used throughout the world, particularly in Asia, with the production of indigo dyestuff economically ...
However, vat dyes, and especially indigo, must be treated after dyeing by 'soaping' to prevent the dye from rubbing (crocking) off. [5] Vat dyes can be used to simultaneously dye the fabric and to remove underlying fiber-reactive dye (i.e., can dye a black cotton fabric yellow) because of the bleaching action of the reducing bath. The extra ...
Direct dyes, a class of dyes largely for dyeing cotton, are water-soluble and can be applied directly to the fiber from an aqueous solution. Most other classes of synthetic dye, other than vat and surface dyes, are also applied in this way. The term may also be applied to dyeing without the use of mordants to fix the dye once it is applied.
The fabric passes over rollers, immerses into a dye bath, and then proceeds through rollers that remove excess dye, allowing it to return to the dye container. [8] The difference between piece-dyeing in a vat and using a pad-dyeing machine is that in the latter, the fabric is continuously moved through one or more dye baths, rather than being ...
Food dyes can be direct, mordant and vat dyes, and their use is strictly controlled by legislation. Many are azo dyes, although anthraquinone and triphenylmethane compounds are used for colors such as green and blue. Some naturally occurring dyes are also used. [20]
Vat Blue 36 is a vat dye that is chemically related to indigo. It is produced by condensation of 4-methyl-5-chloro-7-methoxy-3-indolinone and 5,7–dichloro-3-(2H)-thianaphthenone . [ 1 ]