| A dye can generally be described as a
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| | after-treatment. It is important to note
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| colored substance that has an affinity to
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| | that many mordants, particularly those in
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| the substrate to which it is being
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| | the hard metal category, can be hazardous
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| applied. The dye is generally applied in
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| | to health and extreme care must be taken
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| an aqueous solution, and may require a
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| | in using them.
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| mordant to improve the fastness of the
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| | Look up leuco form in Wiktionary, the
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| dye on the fiber.
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| | free dictionary.
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| Both dyes and pigments appear to be
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| | Vat dyes are essentially insoluble in
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| colored because they absorb some
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| | water and incapable of dyeing fibres
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| wavelengths of light preferentially. In
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| | directly. However, reduction in alkaline
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| contrast with a dye, a pigment generally
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| | liquor produces the water soluble alkali
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| is insoluble, and has no affinity for the
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| | metal salt of the dye, which, in this
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| substrate. Some dyes can be precipitated
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| | leuco form, has an affinity for the
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| with an inert salt to produce a lake
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| | textile fibre. Subsequent oxidation
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| pigment.
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| | reforms the original insoluble dye.
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| Archaeological evidence shows that,
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| | Reactive dyes utilize a chromophore
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| particularly in India and the Middle
| |
| | containing a substituent that is capable
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| East, dyeing has been carried out for
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| | of directly reacting with the fibre
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| over 5000 years. The dyes were obtained
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| | substrate. The covalent bonds that attach
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| from animal, vegetable or mineral origin,
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| | reactive dye to natural fibers make it
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| with no or very little processing. By far
| |
| | among the most permanent of dyes. "Cold"
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| the greatest source of dyes has been from
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| | reactive dyes, such as Procion MX,
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| the plant kingdom, notably roots,
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| | Cibacron F, and Drimarene K, are very
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| berries, bark, leaves and wood, but only
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| | easy to use because the dye can be
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| a few have ever been used on a commercial
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| | applied at room temperature. Reactive
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| scale.
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| | dyes are by far the best choice for
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| Organic dyes
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| | dyeing cotton and other cellulose fibers
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| The first human-made (synthetic) organic
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| | at home or in the art studio.
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| dye, mauveine, was discovered by William
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| | Disperse dyes were originally developed
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| Henry Perkin in 1856. Many thousands of
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| | for the dyeing of cellulose acetate, and
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| synthetic dyes have since been prepared.
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| | are substantially water insoluble. The
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| Synthetic dyes quickly replaced the
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| | dyes are finely ground in the presence of
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| traditional natural dyes. They cost less,
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| | a dispersing agent and then sold as a
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| they offered a vast range of new colors,
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| | paste, or spray-dried and sold as a
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| and they imparted better properties upon
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| | powder. They can also be used to dye
|
| the dyed materials.[1] Dyes are now
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| | nylon, cellulose triacetate, polyester
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| classified according to how they are used
| |
| | and acrylic fibres. In some cases, a
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| in the dyeing process.
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| | dyeing temperature of 130 °C is
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| Acid dyes are water-soluble anionic dyes
| |
| | required, and a pressurised dyebath is
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| that are applied to fibers such as silk,
| |
| | used. The very fine particle size gives a
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| wool, nylon and modified acrylic fibers
| |
| | large surface area that aids dissolution
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| using neutral to acid dyebaths.
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| | to allow uptake by the fibre. The dyeing
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| Attachment to the fiber is attributed, at
| |
| | rate can be significantly influenced by
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| least partly, to salt formation between
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| | the choice of dispersing agent used
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| anionic groups in the dyes and cationic
| |
| | during the grinding.
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| groups in the fiber. Acid dyes are not
| |
| | Azo dyeing is a technique in which an
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| substantive to cellulosic fibers.
| |
| | insoluble azoic dye is produced directly
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| Basic dyes are water-soluble cationic
| |
| | onto or within the fibre. This is
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| dyes that are mainly applied to acrylic
| |
| | achieved by treating a fibre with both
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| fibers, but find some use for wool and
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| | diazoic and coupling components. With
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| silk. Usually acetic acid is added to the
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| | suitable adjustment of dyebath conditions
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| dyebath to help the uptake of the dye
| |
| | the two components react to produce the
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| onto the fiber. Basic dyes are also used
| |
| | required insoluble azo dye. This
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| in the coloration of paper.
| |
| | technique of dyeing is unique, in that
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| Direct or substantive dyeing is normally
| |
| | the final color is controlled by the
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| carried out in a neutral or slightly
| |
| | choice of the diazoic and coupling
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| alkaline dyebath, at or near boiling
| |
| | components.
|
| point, with the addition of either sodium
| |
| | Sulfur dyes are two part "developed" dyes
|
| chloride (NaCl) or sodium sulfate
| |
| | used to dye cotton with dark colors. The
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| (Na2SO4). Direct dyes are used on cotton,
| |
| | initial bath imparts a yellow or pale
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| paper, leather, wool, silk and nylon.
| |
| | chartreuse color. This is oxidized in
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| They are also used as pH indicators and
| |
| | place to produce the dark black we are
|
| as biological stains.
| |
| | familiar with in socks and the indigo
|
| Mordant dyes require a mordant, which
| |
| | blue of the common blue jeans.
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| improves the fastness of the dye against
| |
| | Food dyes
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| water, light and perspiration. The choice
| |
| | One other class which describes the role
|
| of mordant is very important as different
| |
| | of dyes, rather than their mode of use,
|
| mordants can change the final color
| |
| | is the food dye. Because food dyes are
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| significantly. Most natural dyes are
| |
| | classed as food additives, they are
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| mordant dyes and there is therefore a
| |
| | manufactured to a higher standard than
|
| large literature base describing dyeing
| |
| | some industrial dyes. Food dyes can be
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| techniques. The most important mordant
| |
| | direct, mordant and vat dyes, and their
|
| dyes are the synthetic mordant dyes, or
| |
| | use is strictly controlled by
|
| chrome dyes, used for wool; these
| |
| | legislation. Many are azoic dyes,
|
| comprise some 30% of dyes used for wool,
| |
| | although anthraquinone and
|
| and are especially useful for black and
| |
| | triphenylmethane compounds are used for
|
| navy shades. The mordant, potassium
| |
| | colors such as green and blue. Some
|
| dichromate, is applied as an
| |
| | naturally-occurring dyes are also used.
|
