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Thursday, March 12, 2009

Type of dyeing

Acid dye - In this process, water-soluble anionic dyes are applied to fibers from neutral to acid dyebaths. Usually fibers of silk, wool, nylon and modified acrylic are dyed.

Direct (substantive) dye - This process uses either sodium chloride or sodium sulphate in neutral or little alkaline dyebath. Usually cotton, paper, leather, wool, silk and nylon is dyed

Mordent dye - The process requires the use of mordent (a dyeing substance) to improve the fastness of the dye on the fiber like water, light and perspiration fastness.

Vat dye - This dye is insoluble in water and does not dye fiber directly. Reduction in alkaline liquor gives the water soluble alkali metal salt of the dye. This form dyes the textile fiber.

Reactive dye - This dye contain a reactive group, haloheterocycle or activated double bond. It is applied to the fiber in a weakly alkaline dyebath, which forms a chemical bond with an hydroxyl group on the cellulosic fiber.

Disperse dye - A substantially water insoluble, developed for dyeing cellulose acetate. The dyes are ground finely in the presence of a dispersing agent. It is in the form of paste, spray dried, or powders. It is used to dye nylon, triacetate, polyester and acrylic fibers.
Azoic dye - An insoluble azo dye is produced directly onto or within the fiber in this process. This is achieved by the treatment with a diazo component and a coupling component.


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