A dye can generally be described as a colored Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light (distribution of light energy versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of substance that has an affinity In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition to the substrate to which it is being applied. The dye is generally applied in an aqueous solution An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant formula. The word aqueous means pertaining to, related to, similar to, or dissolved in water. As water is an excellent solvent as well as naturally abundant, it is a ubiquitous solvent in chemistry, and may require a mordant A mordant is a substance used to set dyes on fabrics or tissue sections by forming a coordination complex with the dye which then attaches to the fabric or tissue. It may be used for dyeing fabrics, or for intensifying stains in cell or tissue preparations. The term mordant comes from the Latin word, "mordere", to bite. In the past, it 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 Light is electromagnetic radiation of a wavelength that is visible to the human eye . In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not preferentially. In contrast with a dye, a pigment A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light generally is insoluble, and has no affinity for the substrate. Some dyes can be precipitated Precipitation is the formation of a solid in a solution or inside another solid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, and the liquid remaining above the solid is called the supernate. Powders derived from precipitation have also historically been with an inert salt to produce a lake pigment A lake pigment is a pigment manufactured by precipitating a dye with an inert binder, usually a metallic salt. Manufacturers and suppliers to artists and industry frequently omit the lake designation in the name. Many lake pigments are fugitive because the dyes involved are unstable when exposed to light, and based on the salt used they could be aluminum lake, calcium lake or barium lake pigments.

Dyed flax Flax (binomial name: Linum usitatissimum) is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean to India and was probably first domesticated in the Fertile Crescent. It is known as Agasi/Akshi in Kannada, जवस (Jawas/Javas) or अळशी (Alashi) in Marathi and तीसी fibers have been found in the Republic of Georgia Georgia (Georgian: საქართველო, IPA: [sɑkʰɑrtʰvɛlɔ] ; English pronunciation: /ˈdʒɔrdʒə/ ( listen)) is a sovereign state in the Caucasus region of Eurasia. Situated at the juncture of Eastern Europe and Western Asia, it is bounded to the west by the Black Sea, to the north by Russia, to the south by Turkey and Armenia, dated back in a prehistoric cave to 36,000 BP Before Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use 1 January 1950 as the arbitrary origin of the age scale. For example, 1500 BP means 1500 years before 1950, that is, in the year 45.^[1][2] Archaeological Archaeology, or archeology , is the study of past human societies, primarily through the recovery and analysis of the material culture and environmental data which they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes. Due to the fact that archaeology employs a wide range of different procedures, it can be evidence shows that, particularly in India Home to the ancient Indus Valley Civilisation and a region of historic trade routes and vast empires, the Indian subcontinent was identified with its commercial and cultural wealth for much of its long history. Four major religions, Hinduism, Buddhism, Jainism and Sikhism originated here, while Zoroastrianism, Judaism, Christianity and Islam and Phoenicia Phoenicia was an ancient civilization centered in the north of ancient Canaan, with its heartland along the coastal regions of modern day Lebanon, Palestine, Syria and Israel. Phoenician civilization was an enterprising maritime trading culture that spread across the Mediterranean during the period 1550 BC to 300 BC. Though ancient boundaries of, dyeing Dyeing is the process of imparting colours to a textile material in loose fibre, yarn, cloth or garment form by treatment with a dye has been extensively carried out for over 5000 years. The dyes were obtained from animal Animals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and independently. All animals are also, vegetable The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This usually means the leaf, stem, or root of a plant or mineral A mineral is a naturally occurring solid chemical substance that is formed through geological processes and that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not have a specific chemical composition origin, with no or very little processing. By far the greatest source of dyes has been from the plant kingdom Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004,, notably roots In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating (growing up above the ground or especially above water). Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is, berries The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are berries. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors. The seeds are usually embedded in the flesh of the, bark Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes, leaves In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. As an evolutionary trait, the flatness of leaves works to expose the chloroplasts to more light and to increase the absorption of carbon dioxide at the expense of water loss. In the Devonian period, when carbon and wood Wood is a hard, fibrous tissue found in many plants. It has been used for centuries for both fuel and as a construction material for several types of living areas such as houses. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression. In the strict sense wood is produced as, but only a few have ever been used on a commercial scale.

Organic dyes

The first human-made (synthetic) organic An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic. The distinction between "organic" and " dye, mauveine Mauveine, also known as aniline purple and Perkin's mauve, was the first synthetic organic dye. Its chemical name is 3-amino-2,±9-dimethyl-5-phenyl-7-phenazinium acetate. The formula is C26H23N4+X− (mauveine A) and C27H25N4+X− (mauveine B, see below), was discovered by William Henry Perkin Sir William Henry Perkin, FRS was an English chemist best known for his discovery, at the age of 18, of the first aniline dye, mauveine in 1856. Many thousands of synthetic dyes have since been prepared.^[3], ^[4]

Synthetic dyes quickly replaced the traditional natural dyes. They cost less, they offered a vast range of new colors, and they imparted better properties to the dyed materials.^[5] Dyes are now classified according to how they are used in the dyeing process.

Acid dyes Acid dye is a member of a class of dye that is applied from an acidic solution. In the home or art studio, the acid used in the dyebath is often vinegar or citric acid. The uptake rate of the dye is controlled with the use of sodium chloride are water Water is a chemical substance with the chemical formula H2O. Its molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state, water vapor or steam-soluble Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a liquid solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on temperature and pressure. The extent of the solubility of a substance in a anionic In chemistry, an anionic species is one that contains a full negative charge. These types of compounds can range in reactivity dyes that are applied to fibers Fiber, also spelled fibre, is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. They are very important in the biology of both plants and animals, for holding tissues together. Human uses for fibers are diverse. They can be spun into filaments, string or rope, used as a component such as silk Silk is a natural protein fibre, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity . The shimmering appearance of silk is due to the triangular prism-like structure of the silk fibre, which allows silk cloth to refract, wool The term wool is usually restricted to describing the fibrous protein derived from the specialized skin cells called follicles in sheep, nylon Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935 by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station. Nylon is one of the most commonly used polymers and modified acrylic fibers Acrylic fibers are synthetic fibers made from a polymer with an average molecular weight of ~100,000, about 1900 monomer units. To be called acrylic in the U.S, the polymer must contain at least 85% acrylonitrile monomer. Typical comonomers are vinyl acetate or methyl acrylate. The Dupont Corporation created the first acrylic fibers in 1941 and using neutral to acid dye baths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. An anion , from the Greek word ἀνω (anο), meaning "up", is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively groups in the fiber. Acid dyes are not substantive to cellulosic Cellulose is an organic compound with the formula n, a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units fibers. Most synthetic food colors fall in this category.

Basic dyes are water-soluble cationic An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. An anion , from the Greek word ἀνω (anο), meaning "up", is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively dyes that are mainly applied to acrylic fibers Acrylic fibers are synthetic fibers made from a polymer with an average molecular weight of ~100,000, about 1900 monomer units. To be called acrylic in the U.S, the polymer must contain at least 85% acrylonitrile monomer. Typical comonomers are vinyl acetate or methyl acrylate. The Dupont Corporation created the first acrylic fibers in 1941 and, but find some use for wool and silk. Usually acetic acid Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid that gives vinegar its sour taste and pungent smell. It is a weak acid, in that it is only a partially dissociated acid in an aqueous solution. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment (hygroscopy), and freezes at 16.5 °C (62 ° 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 Paper is a thin material mainly used for writing upon, printing upon or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets.

Direct or substantive dyeing Substantive dye is a dye used in a process in which dye molecules are attracted by physical forces at the molecular level to the textile. The amount of this attraction is known as "substantivity": the higher the substantivity the greater the attraction of the dye for the fiber is normally carried out in a neutral or slightly alkaline In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base, especially for soluble bases. This broad use of the dyebath, at or near boiling point The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid, with the addition of either sodium chloride Sodium chloride, also known as salt, common salt, table salt, or halite, is an ionic compound with the formula Na (NaCl) or sodium sulfate Sodium sulfate is the sodium salt of sulfuric acid. Anhydrous, it is a white crystalline solid of formula Na2SO4 known as the mineral thenardite; the decahydrate Na2SO4·10H2O has been known as Glauber's salt or, historically, sal mirabilis since the 17th century. Another solid is the heptahydrate, which transforms to mirabilite when cooled. With (Na₂SO₄). Direct dyes are used on cotton Cotton is a soft, fluffy staple fiber that grows in a boll around the seeds of the cotton plant . The plant is a shrub native to tropical and subtropical regions around the world, including the Americas,Africa , India and Pakistan. The fiber most often is spun into yarn or thread and used to make a soft, breathable textile, which is the most, paper, leather Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry, wool, silk and nylon Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935 by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station. Nylon is one of the most commonly used polymers. They are also used as pH indicators and as biological stains.

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.

Vat dyes 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 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 water insoluble. The dyes are finely ground in the presence of a dispersing agent and 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 °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.

Azoic dyeing is a technique in which an insoluble azo 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 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 dye. Because food dyes are classed as food additives, 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 legislation. Many are azo 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
• Laser dyes
• 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
• Contrast dyes, injected for magnetic resonance imaging, are essentially the same as clothing dye except they are coupled to an agent that has strong paramagnetic properties.[1]

Chemical classification

By the nature of their chromophore, dyes are divided into: [2]

• 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 structure
• Cyanine dyes, derivates of phthalocyanine
• Diazonium dyes, based on diazonium salts
• Nitro dyes, based on a -NO₂ 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

• Biological pigment, any colored substance in organisms
• Hair coloring
• Blue Wool Scale
• Oxidant
• Paper dyeing
• Phototendering
• Stain
• Category:Natural dyes
• Category:Pigments
  • Category:Inorganic pigments
• List of dyes

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