Dye 8179 223554482 2008-07-04T16:18:25Z Iridescent 937705 Reverted edits by [[Special:Contributions/59.178.162.253|59.178.162.253]] to last version by VMS Mosaic (using [[WP:HG|Huggle]]) {{Wiktionarypar|dye}} [[Image:Conner-prairie-yarn-drying.jpg|300px|thumb|Yarn drying after being dyed in the early American tradition, at [[Conner Prairie]] [[living history museum]].]] A '''dye''' can generally be described as a [[color]]ed substance that has an [[Chemical affinity|affinity]] to the [[Wiktionary:substrate|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 [[light]] preferentially. In contrast with a dye, a [[pigment]] generally is insoluble, and has no affinity for the substrate. Some dyes can be [[Precipitation (chemistry)|precipitated]] with an inert salt to produce a [[lake pigment]], and based on the salt used they could be aluminum lake, calcium lake or barium lake pigments. [[Archaeology|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 [[mineral]] origin, with no or very little processing. By far the greatest source of dyes has been from the [[plant kingdom]], notably [[root]]s, [[berry|berries]], [[bark]], [[leaf|leaves]] and [[wood]], but only a few have ever been used on a commercial scale. ==Organic dyes== The first human-made (synthetic) [[organic compound|organic]] dye, [[mauveine]], was discovered by [[Sir William Henry Perkin|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.<ref> {{cite book|title=Mauve: How One Man Invented a Color That Changed the World|author=Simon Garfield|date=2000|publisher=[[Faber and Faber]] |id=ISBN 0-393-02005-3 }}</ref> Dyes are now classified according to how they are used in the dyeing process. '''[[Acid dye]]s''' are [[water]]-[[soluble]] [[anionic]] dyes that are applied to [[fiber]]s such as [[silk]], [[wool]], [[nylon]] and modified [[acrylic fiber]]s using neutral to acid dyebaths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and [[cationic]] groups in the fiber. Acid dyes are not substantive to [[Cellulose|cellulosic]] fibers. Most synthetic food colors fall in this category. '''Basic dyes''' are water-soluble [[cationic]] dyes that are mainly applied to [[acrylic fiber]]s, 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 '''[[substantive dye]]ing''' is normally carried out in a neutral or slightly [[alkaline]] dyebath, at or near [[boiling point]], with the addition of either [[sodium chloride]] (NaCl) or [[sodium sulfate]] (Na<sub>2</sub>SO<sub>4</sub>). Direct dyes are used on [[cotton]], paper, [[leather]], wool, silk and [[nylon]]. They are also used as [[pH indicator]]s and as [[staining (biology)|biological stain]]s. '''Mordant dyes''' require a [[mordant]], which improves the fastness of the dye against water, [[light]] and [[perspiration]]. The choice of mordant is very important as different mordants can change the final color significantly. Most natural dyes are mordant dyes and there is therefore a large literature base describing dyeing techniques. The most important mordant dyes are the synthetic mordant dyes, or chrome dyes, used for wool; these comprise some 30% of dyes used for wool, and are especially useful for black and navy shades. The mordant, [[potassium dichromate]], is applied as an after-treatment. It is important to note that many mordants, particularly those in the heavy metal category, can be hazardous to health and extreme care must be taken in using them. {{wiktionarypar|leuco form}} '''[[Vat dye]]s''' are essentially insoluble in water and incapable of dyeing fibres directly. However, reduction in [[alkaline liquor]] produces the water soluble [[alkali]] [[metal]] [[salt]] of the dye, which, in this leuco form, has an affinity for the textile fibre. Subsequent [[oxidation]] reforms the original insoluble dye. The color of denim is due to indigo, the original vat dye. '''[[Reactive dyes]]''' utilize a [[chromophore]] attached to a [[substituent]] that is capable of directly [[chemical reaction|reacting]] with the fibre substrate. The [[covalent]] bonds that attach reactive dye to natural fibers make them among the most permanent of dyes. "Cold" reactive dyes, such as [[Procion MX]], [[Cibacron F]], and [[Drimarene K]], are very easy to use because the dye can be applied at room temperature. Reactive dyes are by far the best choice for dyeing [[cotton]] and other [[cellulose]] fibers at home or in the art studio. '''Disperse dyes''' were originally developed for the dyeing of [[cellulose acetate]], and are substantially water insoluble. The dyes are finely ground in the presence of a dispersing agent and then sold as a paste, or spray-dried and sold as a powder. Their main use is to dye [[polyester]] but they can also be used to dye nylon, [[cellulose triacetate]], and acrylic fibres. In some cases, a dyeing [[temperature]] of 130 [[Celsius|°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 dye]]ing''' 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 [[component]]s. 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 dye]]s''' are two part "developed" dyes used to dye cotton with dark colors. The initial bath imparts a yellow or pale [[chartreuse]] color. This is aftertreated with a sulfur compound in place to produce the dark black we are familiar with in socks for instance. Sulfur Black 1 is the largest selling dye by volume. == Food dyes == One other class which describes the role of dyes, rather than their mode of use, is the [[food coloring|food dye]]. Because food dyes are classed as [[food additive]]s, they are manufactured to a higher standard than some industrial dyes. Food dyes can be direct, mordant and vat dyes, and their use is strictly controlled by [[law|legislation]]. Many are [[azoic]] dyes, although [[anthraquinone]] and [[triphenylmethane]] compounds are used for colors such as [[green]] and [[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 brightener]]s, for textile fibres and paper * [[Solvent dye]]s, for wood staining and producing colored lacquers, solvent inks, coloring oils, waxes. * [[Carbene dye]]s, a recently developed method for coloring multiple substrates ==Chemical classification== By the nature of their [[chromophore]], dyes are divided into: [http://stainsfile.info/StainsFile/dyes/dyes.htm] * [[:Category:Acridine dyes]], derivates of [[acridine]] * [[:Category:Anthraquinone dyes]], derivates of [[anthraquinone]] * Arylmethane dyes ** [[:Category:Diarylmethane dyes]], based on [[diphenyl]] methane ** [[:Category:Triarylmethane dyes]], derivates of [[triphenyl methane]] * [[:Category:Azo dyes]], based on -N=N- [[azo compound|azo]] structure * Cyanine dyes, derivates of [[phthalocyanine]] * Diazonium dyes, based on [[diazonium]] salts * Nitro dyes, based on a -NO<sub>2</sub> [[nitro functional group]] * Nitroso dyes, based on a -N=O [[nitroso]] functional group * Phthalocyanine dyes, derivates of [[phthalocyanine]] * Quinone-imine dyes, derivates of [[quinone]] ** [[:Category:Azin dyes]] *** [[:Category:Eurhodin dyes]] *** [[:Category:Safranin dyes]], derivates of [[safranin]] ** Indamins ** [[:Category:Indophenol dyes]], derivates of indophenol ** [[:Category:Oxazin dyes]], derivates of oxazin ** Oxazone dyes, derivates of [[oxazone]] ** [[:Category:Thiazin dyes]], derivates of thiazin * [[:Category:Thiazole dyes]], derivates of [[thiazole]] * Xanthene dyes, derived from [[xanthene]] ** Fluorene dyes, derivates of [[fluorene]] *** [[Pyronin]] dyes ** [[:Category:Fluorone dyes]], based on [[fluorone]] *** [[:Category:Rhodamine dyes]], derivates of [[rhodamine]] ==See also== *[[Hair coloring]] *[[Blue Wool Scale]] *[[Phototendering]] *[[Stain]] * [[:Category:Natural dyes]] * [[:Category:Pigments]] ** [[:Category:Inorganic pigments]] ==Notes== <div class="references-small"><references/></div> ==External links== *[http://www.wildcolours.co.uk Growing and using Natural Dyes] *[http://www.pburch.net/dyeing/aboutdyes.shtml About Dyes] *[http://www.oriental-rugs-history.com/dyers-and-dyes.html Dyers and Dyes in Oriental Rugs] *[http://www.deliberatelife.com/index.php?option=com_content&task=view&id=157&Itemid=70 Dyeing fiber with plants] *[http://nariphaltan.virtualave.net/dye.pdf Effect of various dyes on solar distillation] {{Dyeing}} [[Category:Dyes| ]] [[de:Farbstoffe]] [[es:Tinte]] [[fr:Teinture]] [[lt:Dažiklis]] [[nl:Kleurstof]] [[ja:染料]] [[ko:염료]] [[pl:Substancje barwiące]] [[ro:Coloranţi]] [[ru:Красители]] [[simple:Dye]] [[zh:染料]]