Dye



Look up dye in Wiktionary, the free dictionary.

 

A dye can generally be described as a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber.

Both dyes and pigments appear to be colored because they absorb some wavelengths of lake pigment.

Archaeological evidence shows that, particularly in India and the Middle East, dyeing has been carried out for over 5000 years. The dyes were obtained from animal, vegetable or leaves and wood, but only a few have ever been used on a commercial scale.

Organic dyes

The first human-made (synthetic) William Henry Perkin in 1856. Many thousands of synthetic dyes have since been prepared.

Synthetic dyes quickly replaced the traditional natural dyes. They cost less, they offered a vast range of new colors, and they imparted better properties upon the dyed materials.[1] Dyes are now classified according to how they are used in the dyeing process.

cellulosic fibers.

Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers, but find some use for wool and silk. Usually acetic acid is added to the dyebath to help the uptake of the dye onto the fiber. Basic dyes are also used in the coloration of paper.

Direct or pH indicators and as biological stains.

Mordant dyes require a mordant, which improves the fastness of the dye against water, potassium dichromate, is applied as an after-treatment. It is important to note that many mordants, particularly those in the hard metal category, can be hazardous to health and extreme care must be taken in using them.

Look up leuco form in Wiktionary, the free dictionary.

oxidation reforms the original insoluble dye. The indigo color of blue jeans is a vat dye.

Reactive dyes utilize a cellulose fibers at home or in the art studio.

Disperse dyes were originally developed for the dyeing of °C is required, and a pressurised dyebath is used. The very fine particle size gives a large surface area that aids dissolution to allow uptake by the fibre. The dyeing rate can be significantly influenced by the choice of dispersing agent used during the grinding.

Azo dyeing is a technique in which an insoluble azoic dye is produced directly onto or within the fibre. This is achieved by treating a fibre with both diazoic and coupling components. With suitable adjustment of dyebath conditions the two components react to produce the required insoluble azo dye. This technique of dyeing is unique, in that the final color is controlled by the choice of the diazoic and coupling components.

Sulfur dyes are two part "developed" dyes used to dye cotton with dark colors. The initial bath imparts a yellow or pale chartreuse color. This is oxidized in place to produce the dark black we are familiar with in socks.

Food dyes

One other class which describes the role of dyes, rather than their mode of use, is the blue. Some naturally-occurring dyes are also used.

Other important dyes

A number of other classes have also been established, including:

  • Oxidation bases, for mainly hair and fur
  • Leather dyes, for leather
  • Fluorescent brighteners, for textile fibres and paper
  • Solvent dyes, for wood staining and producing colored lacquers, solvent inks, coloring oils, waxes.
  • Carbene dyes, a recently developed method for coloring multiple substrates

Chemical classification

By the nature of their chromophore, dyes are divided into: [1]

See also

Notes

  1. ^ Simon Garfield (2000). Mauve: How One Man Invented a Color That Changed the World. Faber and Faber. ISBN 0-393-02005-3. 
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