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any substance, natural or synthetic, used to color various materials, especially textiles, leather, and food. Natural dyes are so called because they are obtained from plants (e.g., alizarinalizarin
, or 1,2-dihydroxyanthraquinone, mordant vegetable dye obtained originally from the root of the madder plant (Rubia tinctorum), in which it occurs as a glucoside. The term also includes a group of synthetic dyestuffs prepared from coal-tar derivatives.
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, catechucatechu
or cutch,
extract from the heartwood of Acacia catechu, a leguminous tree of the pulse family, native to India and Myanmar. Catechu is a fast brown dye used for various shades of brown and olive, including the familiar khaki, and also in tanning.
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, indigoindigo
[Span.; from Lat.,=Indian], important blue dyestuff used in printing inks and for vat dyeing of cotton (see dye). It was anciently produced in India and was known in Egypt, probably c.1600 B.C.
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, and logwood), from animals (e.g., cochinealcochineal
, natural dye obtained from an extract of the bodies of the females of the cochineal bug (Dactylopius confusus) found on certain species of cactus, especially Nopalea coccinellifera, native to Mexico and Central America.
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, kermes, and Tyrian purple), and from certain naturally occurring minerals (e.g., ocherocher
, mixture of varying proportions of iron oxide and clay, used as a pigment. It occurs naturally as yellow ocher (yellow or yellow-brown in color), the iron oxide being limonite, or as red ocher, the iron oxide being hematite.
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 and Prussian bluePrussian blue,
pigment widely used for laundry bluing, in dyeing compounds, and in the manufacture of inks and paints. Several varieties are known, one of which consists of the chemical compound ferric ferrocyanide.
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). They have been almost entirely replaced in modern dyeing by synthetic dyes. Most of these have been prepared from coal tar or petroleum, being formed from an aromatic hydrocarbonhydrocarbon
, any organic compound composed solely of the elements hydrogen and carbon. The hydrocarbons differ both in the total number of carbon and hydrogen atoms in their molecules and in the proportion of hydrogen to carbon.
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 such as benzene, from which indigo is derived (see also anilineaniline
, C6H5NH2, colorless, oily, basic liquid organic compound; chemically, a primary aromatic amine whose molecule is formed by replacing one hydrogen atom of a benzene molecule with an amino group.
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), or anthracene, which yields alizarin.

Although some materials, e.g., silk and wool, can be colored simply by being dipped in the dye (the dyes so used are consequently called direct dyes), others, including cotton, commonly require the use of a mordantmordant
[Fr.,=biting], substance used in dyeing to fix certain dyes (mordant dyes) in cloth. Either the mordant (if it is colloidal) or a colloid produced by the mordant adheres to the fiber, attracting and fixing the colloidal mordant dye (see colloid); the insoluble, colored
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 (see also lakelake,
in dyeing, an insoluble pigment formed by the reaction between an organic dye and a mordant. The color of a lake depends upon the mordant as well as the dye used. Generally, lakes are not as colorfast as many inorganic dyes, but their colors are more brilliant.
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). Alizarin is a mordant dye and the color it gives depends upon the mordant used. Dyes are classified also as acidic or basic according to the medium required in the dyeing process. A vat dye, e.g., indigo, is so called from the method of its application; it is first treated chemically so that it becomes soluble and is then used for coloring materials bathed in a vat.

When the materials become impregnated with the dye, they are removed and dried in air, the indigo reverting to its original, insoluble form. The process by which a dye becomes "attached" to the material it colors is not definitely known. One theory holds that a chemical reaction takes place between the dye and the treated fiber; another proposes that the dye is absorbed by the fiber.

Dyeing is an ancient industry. The Chinese, Persians, and Indians used natural dyes many centuries ago, including indigo, probably the oldest dye in use, and Tyrian purple, derived from a species of snail. The Egyptians prepared some brilliant colors. In the 13th and 14th cent. dyeing assumed importance in Italy; the methods employed were carried to other parts of Europe and, as new dyes became known, the dyeing industry flourished and grew. Cochineal was introduced from Mexico. Finally, in the 19th cent. the work of W. H. PerkinPerkin, Sir William Henry,
1838–1907, English chemist. In 1856 he discovered the first aniline dye (aniline purple, known as mauve and mauveine); by founding a factory to make it, Perkin established the aniline dye industry in England. He was knighted in 1906.
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 and Adolf von BaeyerBaeyer, Adolf von
(Johann Friedrich Wilhelm Adolf von Baeyer) , 1835–1917, German chemist. He taught at Berlin and Strasbourg and in 1875 succeeded Liebig at Munich.
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 produced the first synthetic dyes.


See S. Robinson, The History of Dyed Textiles (1970); H. Zollinger, Color Chemistry: Syntheses, Properties, and Applications of Organic Dyes and Pigments (1987); D. R. Waring and G. Hallas, ed., The Chemistry and Application of Dyes (1989).


A colored substance which imparts more or less permanent color to other materials. Also known as dyestuff.


A coloring material or compound that imparts color throughout a material by penetration.
References in periodicals archive ?
Dyer felt a shift in his thinking that led him to explore the spiritual aspects of human experience.
Dyer of Central Way in Liverpool was sentenced to 14 months imprisonment.
The young teenage male told the court that Dyer had then partially undressed him, hooking his finger around his trousers to pull them down before lying down and grabbing the boy behind the neck, pulling him down onto him.
Mr Dyer has more than 33 years experience in civil litigation, especially in relation to common law matters including workers compensation, transport accident and public liability matters, Mr Clark said.
Dyer initially applied for long-term care insurance for the client, but she was denied coverage.
SMILE: Amy and Richard with bridesmaid Elle Louise Dyer, Grace Anne Dyer and page boy Matthew Connor Dyer, above, Amy with her maid of honour, Nicola Briggs, right, and Matthew again, left
Dyer and De Guzman (right) argued when the Dutchman refused to let Dyer take a spot-kick to complete his hat-trick.
The life and horrific crimes of Dyer stand apart among the records that chronicle intriguing and horrible tales in the history of crimes.
Dick Dyer Toyota wants to aid the efforts of Harvest Hope by hosting a food drive, gathering the foodstuff that the food bank desperately needs in order to continue its programs.
Mr Dyer, 53, had been found by his wife to be in possession of a disc containing indecent photographs.
As a 12-year-old, Dyer and friend Kaycee Gamez, the daughter of then-Oregon softball coach Rick Gamez, would take ground balls and dream about the future.
Lincoln's keeper Ben Scott denied Ross Dyer on three second-half occasions, Chad Sheppard also had an effort cleared off the line.