Yarn drying after being dyed in the early American tradition, at Conner Prairie living history museum. Conner Prairie is a living history Museum in Fishers Indiana, USA, that preserves the historic William Conner home and recreates part of An open air museum is a distinct type of Museum exhibiting its collections out-of-doors

A dye can generally be described as a colored substance that has an affinity to the substrate to which it is being applied. In Chemical physics and Physical chemistry, chemical affinity can be defined as electronic properties by which dissimilar Chemical species are capable of The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber. A mordant is a substance used to set Dyes on fabrics by forming an insoluble compound with the dye

Both dyes and pigments appear to be colored because they absorb some wavelengths of light preferentially. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 In contrast with a dye, a pigment generally is insoluble, and has no affinity for the substrate. For the drug referred to as "pigment" see Black tar heroin. Some dyes can be 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. Precipitation is the formation of a Solid in a Solution during a Chemical reaction. A Lake pigment is a Pigment manufactured by precipitating a Dye with an Inert binder usually a metallic salt

Archaeological evidence shows that, particularly in India and the Middle East, dyeing has been carried out for over 5000 years. Archaeology, archeology, or archæology (from Greek grc ἀρχαιολογία archaiologia – grc ἀρχαῖος archaīos India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country The Middle East is a Subcontinent with no clear boundaries often used as a synonym to Near East, in opposition to Far East. The dyes were obtained from animal, vegetable or mineral origin, with no or very little processing. The term " vegetable " generally means the edible parts of Plants The definition of the word is traditional rather than Scientific, however A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific By far the greatest source of dyes has been from the plant kingdom, notably roots, berries, bark, leaves and wood, but only a few have ever been used on a commercial scale. Plants are living Organisms belonging to the kingdom Plantae. ROOT is an object-oriented program and library developed by CERN. The word berry has two meanings one based on a botanical definition the other on common identification Bark, also known as periderm is the outermost layer of stems and Roots of Woody plants such as Trees It overlays the Wood and consists In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs

Organic dyes

The first human-made (synthetic) organic dye, mauveine, was discovered by William Henry Perkin in 1856. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Mauveine, also known as Aniline Purple and Perkin's mauve, was the first synthetic organic Dye. Sir William Henry Perkin, FRS ( March 12, 1838 July 14, 1907) was an English Chemist best known for his 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.

Acid dyes are water-soluble anionic dyes that are applied to fibers such as silk, wool, nylon and modified acrylic fibers using neutral to acid dyebaths. Acid dye is a member of a class of Dye that is applied from an acidic solution Water is a common Chemical substance that is essential for the survival of all known forms of Life. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Fiber or fibre is a class of Materials that are continuous filaments or are in discrete elongated pieces similar to lengths of thread. Silk is a natural Protein Fiber, some forms of which can be woven into Textiles The best-known type of silk is obtained from cocoons Wool is the fiber derived from the specialized skin cells called follicles of animals in the Caprinae family principally sheep, but the hair of certain species Overview Nylon is a Thermoplastic silky material first used commercially in a nylon- Bristled Toothbrush (1938 followed more famously by Acrylic fibers are Synthetic fibers made from a polymer ( Polyacrylonitrile) with an average molecular weight of ~100000 Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Acid dyes are not substantive to cellulosic fibers. Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Most synthetic food colors fall in this category.

Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers, but find some use for wool and silk. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Acrylic fibers are Synthetic fibers made from a polymer ( Polyacrylonitrile) with an average molecular weight of ~100000 Usually acetic acid is added to the dyebath to help the uptake of the dye onto the fiber. Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste Basic dyes are also used in the coloration of paper. Paper is thin material mainly used for writing upon printing upon or packaging

Direct or substantive dyeing 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 (Na₂SO₄). 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. In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Sodium sulfate is the Sodium salt of Sulfuric acid Direct dyes are used on cotton, paper, leather, wool, silk and nylon. Cotton is a soft staple Fibre that grows around the seeds of the cotton plant ( Gossypium sp Leather is a material created through the Tanning of hides and Skins of Animals primarily Cattlehide The Tanning process Overview Nylon is a Thermoplastic silky material first used commercially in a nylon- Bristled Toothbrush (1938 followed more famously by They are also used as pH indicators and as biological stains. A pH indicator is a halochromic chemical compound that is added in small amounts to a Solution so that the PH ( Acidity or Staining is an auxiliary Technique used in Microscopy to enhance contrast in the microscopic image

Mordant dyes require a mordant, which improves the fastness of the dye against water, light and perspiration. A mordant is a substance used to set Dyes on fabrics by forming an insoluble compound with the dye Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 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. Potassium dichromate, K2Cr2O7 is a common inorganic chemical reagent most commonly used as an Oxidizing agent in various laboratory 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. Vat dyes are an ancient class of Dyes based on the natural dye Indigo, which is now produced synthetically 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. Lye is a Corrosive alkaline substance commonly Sodium hydroxide (NaOH In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants Subsequent oxidation reforms the original insoluble dye. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state 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. In a reactive dye a Chromophore contains a Substituent that is activated and allowed to directly react to the surface of the substrate A chromophore is part (or moiety) of a Molecule responsible for its Color. In Organic chemistry, a substituent is an atom or group of atoms substituted in place of a Hydrogen atom on the Parent chain of a Hydrocarbon A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called 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. Procion is a brand of fibre Reactive dyes Procion MX are a class of cold Reactive dyes. Reactive dyes are by far the best choice for dyeing cotton and other cellulose fibers at home or in the art studio. Cotton is a soft staple Fibre that grows around the seeds of the cotton plant ( Gossypium sp Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4

Disperse dyes were originally developed for the dyeing of cellulose acetate, and are substantially water insoluble. Cellulose acetate, first prepared in 1865 is the Acetate Ester of Cellulose. 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. Polyester is a category of Polymers which contain the Ester Functional group in their main chain Cellulose triacetate, also known simply as triacetate, is manufactured from Cellulose and Acetate. In some cases, a dyeing temperature of 130 °C is required, and a pressurised dyebath is used. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The Celsius Temperature scale was previously known as the centigrade scale. 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. Azo compounds are compounds bearing the Functional group R-N=N-R' in which R and R' can be either Aryl or Alkyl. 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. Sulfur dyes are the most commonly used Dyes manufactured for Cotton in terms of volume 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. A food coloring is any substance that is added to Food or Drink to change its Color. Because food dyes are classed as food additives, they are manufactured to a higher standard than some industrial dyes. Food additives are substances added to food to preserve flavour or improve its taste and appearance Food dyes can be direct, mordant and vat dyes, and their use is strictly controlled by legislation. Law is a system of rules enforced through a set of Institutions used as an instrument to underpin civil obedience politics economics and society Many are azoic dyes, although anthraquinone and triphenylmethane compounds are used for colors such as green and blue. Anthraquinone ( 910-dioxoanthracene) is an aromatic Organic compound. Triphenylmethane, or triphenyl methane, is the Hydrocarbon with the formula (C6H53CH Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. Blue is a Colour, the Perception of which is evoked by 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. Leather is a material created through the Tanning of hides and Skins of Animals primarily Cattlehide The Tanning process Optical brighteners, optical brightening agents (OBAs, fluorescent brightening agents (FBAs or fluorescent whitening agents (FWAs are Dyes A solvent dye is a Dye soluble in Organic solvents It is usually used as a solution in an organic solvent
• Carbene dyes, a recently developed method for coloring multiple substrates

Chemical classification

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

• 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

• Hair coloring
• Blue Wool Scale
• Phototendering
• Stain
• Category:Natural dyes
• Category:Pigments
  • Category:Inorganic pigments

Notes

External links

• Growing and using Natural Dyes
• About Dyes
• Dyers and Dyes in Oriental Rugs
• Dyeing fiber with plants
• Effect of various dyes on solar distillation