A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and may require a mordant to improve the fastness of the dye on the fiber.
95-773: The majority of natural dyes are derived from non-animal sources such as roots, berries, bark, leaves, wood, fungi and lichens . However, due to large-scale demand and technological improvements, most dyes used in the modern world are synthetically produced from substances such as petrochemicals. Some are extracted from insects and/or minerals . Synthetic dyes are produced from various chemicals. The great majority of dyes are obtained in this way because of their superior cost, optical properties (color), and resilience (fastness, mordancy). Both dyes and pigments are colored, because they absorb only some wavelengths of visible light . Dyes are usually soluble in some solvent, whereas pigments are insoluble. Some dyes can be rendered insoluble with
190-420: A chlorin -type ring in the case of chlorophyll. The highly conjugated pi-bonding system of the macrocycle ring absorbs visible light. The nature of the central metal can also influence the absorption spectrum of the metal-macrocycle complex or properties such as excited state lifetime. The tetrapyrrole moiety in organic compounds which is not macrocyclic but still has a conjugated pi-bond system still acts as
285-493: A ferrous sulfate (copperas) mordant. Despite changing fashions in color, logwood was the most widely used dye by the 19th century, providing the sober blacks of formal and mourning clothes. Synthetic dyes, which could be quickly produced in large quantities, quickly superseded natural dyes for the commercial textile production enabled by the Industrial Revolution , and unlike natural dyes, were suitable for
380-497: A radio antenna detects photons along its length. Typically, the more conjugated (longer) the pi-system is, the longer the wavelength of photon can be captured. In other words, with every added adjacent double bond we see in a molecule diagram, we can predict the system will be progressively more likely to appear yellow to our eyes as it is less likely to absorb yellow light and more likely to absorb red light. ("Conjugated systems of fewer than eight conjugated double bonds absorb only in
475-489: A chromophore's structure go into determining at what wavelength region in a spectrum the chromophore will absorb. Lengthening or extending a conjugated system with more unsaturated (multiple) bonds in a molecule will tend to shift absorption to longer wavelengths. Woodward–Fieser rules can be used to approximate ultraviolet -visible maximum absorption wavelength in organic compounds with conjugated pi-bond systems. Some of these are metal complex chromophores, which contain
570-478: A chromophore. Examples of such compounds include bilirubin and urobilin , which exhibit a yellow color. An auxochrome is a functional group of atoms attached to the chromophore which modifies the ability of the chromophore to absorb light, altering the wavelength or intensity of the absorption. Halochromism occurs when a substance changes color as the pH changes. This is a property of pH indicators , whose molecular structure changes upon certain changes in
665-588: A commercial scale. Early industrialization was conducted by J. Pullar and Sons in Scotland. The first synthetic dye, mauve , was discovered serendipitously by William Henry Perkin in 1856. The discovery of mauveine started a surge in synthetic dyes and in organic chemistry in general. Other aniline dyes followed, such as fuchsine , safranine , and induline . Many thousands of synthetic dyes have since been prepared. The discovery of mauve also led to developments within immunology and chemotherapy . In 1863
760-399: A complete rainbow palette. Swedish and American mycologists, building upon Rice's research, have discovered sources for true blues ( Sarcodon squamosus ) and mossy greens ( Hydnellum geogenium ). Hypholoma fasciculare provides a yellow dye, and fungi such as Phaeolus schweinitzii and Pisolithus tinctorius are used in dyeing textiles and paper. From the second millennium BC to
855-553: A complex formula for yellow that employs a dock plant (most likely Rumex crispus ) for yellow. Navajo artists create yellow dyes from small snake-weed , brown onion skins, and rubber plant ( Parthenium incanum ). Rabbitbush ( Chrysothamnus ) and rose hips produce pale, yellow-cream colored dyes. If plants that yield yellow dyes are common, plants that yield green dyes are rare. Both woad and indigo have been used since ancient times in combination with yellow dyes to produce shades of green. Medieval and Early Modern England
950-488: A deep brown approaching black. Today black walnut is primarily used to dye baskets but has been used in the past for fabrics and deerhide. Juniper, Juniperus monosperma , ashes provide brown and yellow dyes for Navajo people , as do the hulls of wild walnuts ( Juglans major ). Khaki , which translates a Hindustani word signifying "soil-colored", was introduced into British uniforms in India, which were dyed locally with
1045-424: A dye prepared from the native mazari palm Nannorrhops . Choctaw dyers use maple ( Acer sp.) for a grey dye. Navajo weavers create black from mineral yellow ochre mixed with pitch from the piñon tree ( Pinus edulis ) and the three-leaved sumac ( Rhus trilobata ). They also produce a cool gray dye with blue flower lupine and a warm gray from Juniper mistletoe ( Phoradendron juniperinum ). In
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#17328007137381140-439: A living body - administered by injection or other means (intravital staining) - as the latter is (for instance) subject to higher safety standards, and must typically be a chemical known to avoid causing adverse effects on any biochemistry (until cleared from the tissue), not just to the tissue being studied, or in the short term. The term "vital stain" is occasionally used interchangeably with both intravital and supravital stains,
1235-406: A metal in a coordination complex with ligands. Examples are chlorophyll , which is used by plants for photosynthesis and hemoglobin , the oxygen transporter in the blood of vertebrate animals. In these two examples, a metal is complexed at the center of a tetrapyrrole macrocycle ring: the metal being iron in the heme group (iron in a porphyrin ring) of hemoglobin, or magnesium complexed in
1330-406: A microscope). As the visibility is meant to allow study of the cells or tissues, it is usually important that the dye not have other effects on the structure or function of the tissue that might impair objective observation. A distinction is drawn between dyes that are meant to be used on cells that have been removed from the organism prior to study (supravital staining) and dyes that are used within
1425-708: A number of non-metal salt substances can be used to assist with the molecular bonding of natural dyes to natural fibres—either on their own, or in combination with metal salt mordants—including tannin from oak galls and a range of other plants/plant parts , "pseudo-tannins", such as plant-derived oxalic acid, and ammonia from stale urine . Plants that bio-accumulate aluminum have also been used. Some mordants, and some dyes themselves, produce strong odors, and large-scale dyeworks were often isolated in their own districts. Throughout history, people have dyed their textiles using common, locally available materials, but scarce dyestuffs that produced brilliant and permanent colors such as
1520-570: A number of weedy flowering plants. Limited evidence suggests the use of weld ( Reseda luteola ), also called mignonette or dyer's rocket before the Iron Age, but it was an important dye of the ancient Mediterranean and Europe and is indigenous to England. Two brilliant yellow dyes of commercial importance in Europe from the 18th century are derived from trees of the Americas : quercitron from
1615-417: A particular wavelength and reflects color as a result. Chromophores are commonly referred to as colored molecules for this reason. The word is derived from Ancient Greek χρῶμᾰ (chroma) 'color' and -φόρος (phoros) 'carrier of'. Many molecules in nature are chromophores, including chlorophyll , the molecule responsible for the green colors of leaves . The color that
1710-771: A piece of silk or any other desired material. The colorant at this stage has the consistency of fine, red mud. Color used as a dye can be diluted. 1.5 kilograms (3.3 lb) of dried florets produces enough dye pigment to dye a small piece of fabric. The dye color is fixed in the fabric with a mordant . Darker shades are achieved by repeating the dyeing process several times, having the fabric dry, and redyed. Dyes that create reds and yellows can also yield oranges. Navajo dyers create orange dyes from one-seeded juniper, Juniperus monosperma , Navajo tea , Thelesperma gracile , or alder bark. Yellow dyes are "about as numerous as red ones", and can be extracted from saffron , pomegranate rind, turmeric , safflower , onion skins, and
1805-521: A purple-red dye which is extracted from several genera of sea snails , primarily the spiny dye-murex Murex brandaris (currently known as Bolinus brandaris ). Murex dye was greatly prized in antiquity because it did not fade, but instead became brighter and more intense with weathering and sunlight. Murex dyeing may have been developed first by the Minoans of East Crete or the West Semites along
1900-427: A range of reddish-purples, blues, violets, greens and reds became available by 1880. These dyes had great affinity for animal fibres such as wool and silk. Although some new colors tended to fade and wash out, others were identical to natural dyes, e.g., indigo dye . By the 1870s commercial dyeing with natural dyestuffs was fast disappearing. Chromophore A chromophore is a molecule which absorbs light at
1995-502: A stronger dye and could thus be used in smaller quantities, replaced kermes dyes in general use in Europe from the 17th century. During the course of the 15th century, the civic records show brilliant reds falling out of fashion for civic and high-status garments in the Duchy of Burgundy in favor of dark blues, greens, and most important of all, black. The origins of the trend for somber colors are elusive, but are generally attributed to
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#17328007137382090-406: A variety of colors and shades from the same dye, as many mordants not only fix the natural dye compounds to the fibre, but can also modify the final dye color. Fibres or cloth may be pretreated with mordants (pre-mordant), or the mordant may be incorporated in the dyebath (meta-mordant, or co-mordant), or the mordanting may be done after dyeing (post-mordant). Natural alum (aluminum sulfate) has been
2185-520: Is a popular red dye among Southeastern Native American basketweavers. Choctaw basketweavers additionally use sumac for red dye. Coushattas artists from Texas and Louisiana used the water oak ( Quercus nigra L.) to produce red. A delicate rose color in Navajo rugs comes from fermented prickly pear cactus fruit, Opuntia polyacantha . Navajo weavers also use rainwater and red dirt to create salmon-pink dyes. In Japan , dyers have mastered
2280-559: Is added to the dye bath to help the uptake of the dye onto the fiber. Basic dyes are also used in the coloration of paper . Direct or substantive dyeing is normally carried out in a neutral or slightly alkaline dye bath, at or near boiling point , with the addition of either sodium chloride (NaCl) or sodium sulfate (Na 2 SO 4 ) or sodium carbonate (Na 2 CO 3 ). Direct dyes are used on cotton , paper, leather , wool, silk and nylon . They are also used as pH indicators and as biological stains . Laser dyes are used in
2375-523: Is reflected in the Greek word for the dye, which was indikon (ινδικόν). The Romans used the term indicum , which passed into Italian dialect and eventually into English as the word indigo . In the Philippines , blue to indigo colors were also obtained from Indigofera tinctoria and related species, known under common names including tarum , dagum , tayum . In Central and South America ,
2470-569: Is seen by our eyes is that of the light not absorbed by the reflecting object within a certain wavelength spectrum of visible light . The chromophore indicates a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum (or in informal contexts, the spectrum under scrutiny). Visible light that hits the chromophore can thus be absorbed by exciting an electron from its ground state into an excited state . In biological molecules that serve to capture or detect light energy,
2565-560: Is still popular with natural dyers. Across Asia and Africa and the Americas, patterned fabrics were produced using resist dyeing techniques to control the absorption of color in piece-dyed cloth. In China, Japan, India, Pakistan , Nigeria , Gambia , and other parts of West Africa and southeast Asia , patterned silk and cotton fabrics were produced using techniques in which the cloth is printed or stenciled with starch or wax , or tied in various ways to prevent even penetration of
2660-485: 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. A number of other classes have also been established, including: By
2755-427: Is to use a tannin first (tannins have high affinity for both protein and cellulose fibres), then use an aluminum salt. The most common method for preparing protein fibres is to use alum. However, the historic record contains many hundreds of different mordanting methods for both protein and cellulose fibres. The types of natural dyes currently popular with craft dyers and the global fashion industry include: Colors in
2850-463: Is used. The very fine particle size gives a large surface area that aids dissolution to allow uptake by the fiber. 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 fiber. This is achieved by treating a fiber with both diazoic and coupling components . With suitable adjustment of dyebath conditions
2945-776: The British East India Company . Woad was carried to New England in the 17th century and used extensively in America until native stands of indigo were discovered in Florida and the Carolinas. In Sumatra , indigo dye is extracted from some species of Marsdenia . Other indigo-bearing dye plants include dyer's knotweed ( Polygonum tinctorum ) from Japan and the coasts of China, and the West African shrub Lonchocarpus cyanescens . The cultivation of indigo
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3040-527: The Levantine coast, and heaps of crushed murex shells have been discovered at a number of locations along the eastern Mediterranean dated to the mid-2nd millennium BC. The classical dye known as Phoenician Red was also derived from murex snails. Murex dyes were fabulously expensive – one snail yields but a single drop of dye – and the Roman Empire imposed a strict monopoly on their use from
3135-617: The Mediterranean region). The dye is of ancient origin; jars of kermes have been found in a Neolithic cave-burial at Adaoutse, Bouches-du-Rhône . Similar dyes are extracted from the related insects Porphyrophora hamelii ( Armenian cochineal ) of the Caucasus region, Porphyrophora polonica ( Polish cochineal or Saint John's blood) of Eastern Europe, and the lac -producing insects of India, Southeast Asia , China, and Tibet . When kermes-dyed textiles achieved prominence around
3230-525: The Neolithic period. In China, dyeing with plants, barks and insects has been traced back more than 5,000 years. The essential process of dyeing changed little over time. Typically, the dye material is put in a pot of water and heated to extract the dye compounds into solution with the water. Then the textiles to be dyed are added to the pot, and held at heat until the desired color is achieved. Textile fibre may be dyed before spinning or weaving ("dyed in
3325-473: The Philippines , black dye was obtained from ebony ( knalum or batulinao ) leaves, as well as from indigo . Dye-bearing lichen produce a wide range of greens, oranges, yellows, reds, browns, and bright pinks and purples. The lichen Rocella tinctoria was found along the Mediterranean Sea and was used by the ancient Phoenicians . In recent times, lichen dyes have been an important part of
3420-569: The Republic of Georgia in a prehistoric cave dated to 36,000 BP . Archaeological evidence shows that, particularly in India and Phoenicia , dyeing has been widely carried out for over 5,000 years. Early dyes were obtained from animal , vegetable or mineral sources, with no to very little processing. By far the greatest source of dyes has been from the plant kingdom , notably roots, berries, bark, leaves and wood, only few of which are used on
3515-517: The Spanish treasure fleets, and the dyestuffs of Europe were carried by colonists to America. The discovery of man-made synthetic dyes in the mid-19th century triggered a long decline in the large-scale market for natural dyes. In the early 21st century, the market for natural dyes in the fashion industry is experiencing a resurgence. Western consumers have become more concerned about the health and environmental impact of synthetic dyes—which require
3610-717: The "ruddy" range of reds, browns, and oranges are the first attested colors in a number of ancient textile sites ranging from the Neolithic to the Bronze Age across the Levant , Egypt , Mesopotamia and Europe , followed by evidence of blues and then yellows, with green appearing somewhat later. The earliest surviving evidence of textile dyeing was found at the large Neolithic settlement at Çatalhöyük in southern Anatolia , where traces of red dyes, possible from ochre ( iron oxide pigments from clay ), were found. Polychrome or multicolored fabrics seem to have been developed in
3705-530: The 14th and early 15th century, brilliant full grain kermes scarlet was "by far the most esteemed, most regal" color for luxury woollen textiles in the Low Countries , England, France, Spain and Italy. Cochineal ( Dactylopius coccus ) is a scale insect of Central and North America from which the crimson -colored dye carmine is derived. It was used by the Aztec and Maya peoples. Moctezuma in
3800-763: The 15th century collected tribute in the form of bags of cochineal dye. Soon after the Spanish conquest of the Aztec Empire cochineal began to be exported to Spain, and by the seventeenth century it was a commodity traded as far away as India. During the colonial period the production of cochineal (in Spanish, grana fina ) grew rapidly. Produced almost exclusively in Oaxaca by indigenous producers, cochineal became Mexico's second most valued export after silver. Cochineal produces purplish colors alone and brilliant scarlets when mordanted with tin; thus cochineal, which produced
3895-402: The 19th century, a succession of rare and expensive natural dyestuffs came in and out of fashion in the ancient world and then in Europe. In many cases the cost of these dyes far exceeded the cost of the wools and silks they colored, and often only the finest grades of fabrics were considered worthy of the best dyes. The premier luxury dye of the ancient world was Tyrian purple or royal purple,
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3990-527: The 3rd or 2nd millennium BCE. Textiles with a "red-brown warp and an ochre-yellow weft " were discovered in Egyptian pyramids of the Sixth Dynasty (2345–2180 BCE). The chemical analysis that would definitively identify the dyes used in ancient textiles has rarely been conducted, and even when a dye such as indigo blue is detected it is impossible to determine which of several indigo-bearing plants
4085-592: The Northwest Plateau in North America used lichen to dye corn husk bags a sea green. Navajo textile artist Nonabah Gorman Bryan developed a two-step process for creating green dye. First the Churro wool yarn is dyed yellow with sagebrush , Artemisia tridentata , and then it is soaked in black dye afterbath. Red onion skins are also used by Navajo dyers to produce green. Blue colorants around
4180-504: The addition of salt to produce a lake pigment . Textile dyeing dates back to the Neolithic period. Throughout history, people have dyed their textiles using common, locally available materials. Scarce dyestuffs that produced brilliant and permanent colors such as the natural invertebrate dyes Tyrian purple and crimson kermes were highly prized luxury items in the ancient and medieval world. Plant-based dyes such as woad , indigo , saffron , and madder were important trade goods in
4275-497: The aromatic rings conjugate. Because of their limited extent, the aromatic rings only absorb light in the ultraviolet region, and so the compound appears colorless in the 0-8 pH range. However, as the pH increases beyond 8.2, that central carbon becomes part of a double bond becoming sp hybridized and leaving a p orbital to overlap with the π-bonding in the rings. This makes the three rings conjugate together to form an extended chromophore absorbing longer wavelength visible light to show
4370-414: The berries of White Bryony from the northern Rocky Mountain states and mulberry ( morus nigra ) (with an acid mordant). Cutch is an ancient brown dye from the wood of acacia trees, particularly Acacia catechu , used in India for dyeing cotton . Cutch gives gray-browns with an iron mordant and olive-browns with copper. Black walnut ( Juglans nigra ) is used by Cherokee artists to produce
4465-426: The burnt ash of Chenopodium album var. centrorubrum is added to release the red colorant. The batch is then kneaded with one's hands and strained. Vinegar is then added to the solution, and the colorant is soaked up by using strips of linen. The strips of linen (now red) are then placed in a separate container and alkali obtained from the burnt ash of Chenopodium album var. centrorubrum is added once more to release
4560-420: The chromophore is the moiety that causes a conformational change in the molecule when hit by light. Just like how two adjacent p-orbitals in a molecule will form a pi-bond , three or more adjacent p-orbitals in a molecule can form a conjugated pi-system . In a conjugated pi-system, electrons are able to capture certain photons as the electrons resonate along a certain distance of p-orbitals - similar to how
4655-445: The color has evenly transferred to the textiles. Some dyestuffs, such as indigo and lichens , will give good color when used alone; these dyes are called direct dyes or substantive dyes . The majority of plant dyes, however, also require the use of a mordant , a chemical used to "fix" the color in the textile fibres . These dyes are called adjective dyes or "mordant dyes". By using different mordants, dyers can often obtain
4750-464: The dawn of Early Modern period , a new and superior method of dyeing black dye reached Europe via Spanish conquests in the New World. The new method used logwood ( Haematoxylum campechianum ), a dyewood native to Mexico and Central America. Although logwood was poorly received at first, producing a blue inferior to that of woad and indigo, it was discovered to produce a fast black in combination with
4845-615: The dye traditions of Wales , Ireland , Scotland , and among native peoples of the southwest and Intermontane Plateaus of the United States . Scottish lichen dyes include cudbear (also called archil in England and litmus in the Netherlands), and crottle. The American artist Miriam C. Rice pioneered research into using various mushrooms for natural dyes. Starting in the late 1960s, she discovered mushroom dyes for
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#17328007137384940-445: The dye when the cloth is piece-dyed. The Chinese ladao process is dated to the 10th century; other traditional techniques include tie-dye , batik , Rōketsuzome , katazome , bandhani and leheria . Some mordants and some dyestuffs produce strong odours, and the process of dyeing often depends on a good supply of fresh water, storage areas for bulky plant materials, vats which can be kept heated (often for days or weeks) along with
5035-410: 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 fibers. In some cases, a dyeing temperature of 130 °C (266 °F) is required, and a pressurized dyebath
5130-460: The dyeing process and his theories on color brought much praise by the well known poet and artist Johann Wolfgang von Goethe . After mordanting, the essential process of dyeing requires soaking the material containing the dye (the dyestuff ) in water, adding the textile to be dyed to the resulting solution (the dyebath ), and bringing the solution to a simmer for an extended period, often measured in days or even weeks, stirring occasionally until
5225-457: The economies of Asia and Europe. Across Asia and Africa, patterned fabrics were produced using resist dyeing techniques to control the absorption of color in piece-dyed cloth. Dyes from the New World such as cochineal and logwood were brought to Europe by the Spanish treasure fleets, and the dyestuffs of Europe were carried by colonists to America. Dyed flax fibers have been found in
5320-500: The fabric in a solution of an organic compound, typically a nitrophenol derivative, and sulfide or polysulfide . The organic compound reacts with the sulfide source to form dark colors that adhere to the fabric. Sulfur Black 1, the largest selling dye by volume, does not have a well defined chemical structure. Some dyes commonly used in Staining: One other class that describes the role of dyes, rather than their mode of use,
5415-454: 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 cellulosic fibers. Most synthetic food colors fall in this category. Examples of acid dye are Alizarine Pure Blue B, Acid red 88 , etc. Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers , but find some use for wool and silk. Usually acetic acid
5510-448: The fiber 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
5605-401: The forerunner to Bayer AG was formed in what became Wuppertal , Germany . In 1891, Paul Ehrlich discovered that certain cells or organisms took up certain dyes selectively. He then reasoned that a sufficiently large dose could be injected to kill pathogenic microorganisms, if the dye did not affect other cells. Ehrlich went on to use a compound to target syphilis , the first time a chemical
5700-526: The genus Rubia are native to many temperate zones around the world, and were already used as sources of good red dye in prehistory. Madder has been identified on linen in the tomb of Tutankhamun , and Pliny the Elder records madder growing near Rome. Madder was a dye of commercial importance in Europe, being cultivated in the Netherlands and France to dye the red coats of military uniforms until
5795-560: The growing influence of Spain and possibly the importation of Spanish merino wools. The trend spread in the next century: the Low Countries, German states , Scandinavia , England, France, and Italy all absorbed the sobering and formal influence of Spanish dress after the mid-1520s. Producing fast black in the Middle Ages was a complicated process involving multiple dyeings with woad or indigo followed by mordanting, but at
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#17328007137385890-462: The imperial family. Tyrian purple retained its place as the premium dye of Europe until it was replaced "in status and desirability" by the rich crimson reds and scarlets of the new silk - weaving centers of Italy, colored with kermes . Kermes is extracted from the dried unlaid eggs of the insect Kermes vermilio or Kermococcus vermilio found on species of oak (especially the Kermes oak of
5985-478: The important blue dyes were Añil ( Indigofera suffruticosa ) and Natal indigo ( Indigofera arrecta ). In temperate climates including Europe, indigo was obtained primarily from woad ( Isatis tinctoria ), an indigenous plant of Assyria and the Levant which has been grown in Northern Europe over 2,000 years, although from the 18th century it was mostly replaced by superior Indian indigo imported by
6080-482: The inner bark of Eastern Black Oak ( Quercus velutina ), native to eastern North America and fustic from the dyer's mulberry tree ( Maclura tinctoria ) of the West Indies and Mexico . In rivercane basketweaving among Southeastern Woodlands tribes in the Americas, butternut ( Juglans cinerea ) and yellow root ( Xanthorhiza simplicissima ) provide a rich yellow color. Chitimacha basket weavers have
6175-432: The luxury dyes kermes and cochineal . Madder could also produce purples when used with alum. Brazilwood also gave purple shades with vitriol ( sulfuric acid ) or potash. In China , purple root/gromwell ( Lithospermum purpurocaeruleum ) has been used to produce a purple dye. Choctaw artists traditionally used maple ( Acer sp.) to create lavender and purple dyes. Purples can also be derived from lichens , and from
6270-456: The market collapsed following the development of synthetic alizarin dye in 1869. Madder was also used to dye the "hunting pinks" of Great Britain. Turkey red was a strong, very fast red dye for cotton obtained from madder root via a complicated multistep process involving " sumac and oak galls, calf's blood, sheep's dung, oil, soda, alum, and a solution of tin". Turkey red was developed in India and spread to Turkey. Greek workers familiar with
6365-534: The methods of its production were brought to France in 1747, and Dutch and English spies soon discovered the secret. A sanitized version of Turkey red was being produced in Manchester by 1784, and roller-printed dress cottons with a Turkey red ground were fashionable in England by the 1820s. Munjeet or Indian madder ( Rubia cordifolia ) is native to the Himalayas and other mountains of Asia and Japan. Munjeet
6460-415: The mid-11th century, the dyestuff was called "grain" in all Western European languages because the desiccated eggs resemble fine grains of wheat or sand. Textiles dyed with kermes were described as dyed in the grain . Woollens were frequently dyed in the fleece with woad and then piece-dyed in kermes, producing a wide range colors from blacks and grays through browns, murreys , purples, and sanguines . By
6555-891: The most common metallic salt mordant for millennia (see Papyrus Graecus Holmiensis , mordant and dye recipes start at recipe #84), but tin ( stannous chloride ), copper ( cupric sulfate ), iron ( ferrous sulfate , called copperas ) and chrome ( potassium dichromate ) are also used. Iron mordants "sadden" colors, while alum and tin mordants brighten colors. Iron, chrome and tin mordants contribute to fabric deterioration, referred to as "dye rot". Additional modifiers may be used during or after dying to protect fibre structure, shift pH to achieve different color results, or for any number of other desirably outcomes. Metal-salt accumulating plants (including club mosses ) were also commonly used as mordants in parts of Europe, but are now endangered in many areas. The Symplocos genus of plants, which grows in semi-tropical regions, also bioaccumulates aluminum, and
6650-503: The natural invertebrate dyes Tyrian purple and crimson kermes became highly prized luxury items in the ancient and medieval world. A less expensive substitute for Tyrian purple was the purple/violet colored Folium also called Turnasole . Plant-based dyes such as woad ( Isatis tinctoria ), indigo , saffron , and madder were important trade goods in the economies of Asia, Africa and Europe. Dyes such as cochineal and logwood ( Haematoxylum campechianum ) were brought to Europe by
6745-714: The nature of their chromophore , dyes are divided into: Dyes produced by the textile, printing and paper industries are a source of pollution of rivers and waterways. An estimated 700,000 tons of dyestuffs are produced annually (1990 data). The disposal of that material has received much attention, using chemical and biological means. A "vital dye" or stain is a dye capable of penetrating living cells or tissues without causing immediate visible degenerative changes. Such dyes are useful in medical and pathological fields in order to selectively color certain structures (such as cells) in order to distinguish them from surrounding tissue and thus make them more visible for study (for instance, under
6840-438: The necessary fuel, and airy spaces to dry the dyed textiles. Ancient large-scale dye-works tended to be located on the outskirts of populated areas. A variety of plants produce red (or reddish) dyes, including a number of lichens , henna , alkanet or dyer's bugloss ( Alkanna tinctoria ), asafoetida , sappanwood, various galium species, and dyer's madder Rubia tinctorum and Rubia cordifolia . Madder and related plants of
6935-495: The once-famous Kendal green. This in turn fell out of fashion in the 18th century in favor of the brighter Saxon green, dyed with indigo and fustic. Soft olive greens are also achieved when textiles dyed yellow are treated with an iron mordant. The dull green cloth common to the Iron Age Halstatt culture shows traces of iron, and was possibly colored by boiling yellow-dyed cloth in an iron pot. Indigenous peoples of
7030-626: The percentage of total cells that stain negatively. Because the dye determines whether the staining is supravital or intravital, a combination of supravital and vital dyes can be used to more accurately classify cells into various groups (e.g., viable, dead, dying). Natural dye Natural dyes are dyes or colorants derived from plants , invertebrates , or minerals . The majority of natural dyes are vegetable dyes from plant sources— roots , berries , bark , leaves , and wood —and other biological sources such as fungi . Archaeologists have found evidence of textile dyeing dating back to
7125-473: The production of some lasers, optical media ( CD-R ), and camera sensors ( color filter array ). 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
7220-405: The red absorbed by the linen. The solution obtained is then poured into a separate container. An extract made from plums that have been covered with soot and fumigated in a smoking pit for 24 hours, followed by a drying period of one month in the sun, is then used as a color fixing mordant. The dried plums are steeped in water and mixed with the color pigment, causing the colorant to precipitate onto
7315-494: The reign of Alexander Severus (AD 225–235) that was maintained by the succeeding Byzantine Empire until the Early Middle Ages . The dye was used for imperial manuscripts on purple parchment , often with text in silver or gold, and porphyrogenitos or " born in the purple " was a term for Byzantine offspring of a reigning Emperor. The color matched the increasingly rare purple rock porphyry , also associated with
7410-400: The surrounding pH. This change in structure affects a chromophore in the pH indicator molecule. For example, phenolphthalein is a pH indicator whose structure changes as pH changes as shown in the following table: In a pH range of about 0-8, the molecule has three aromatic rings all bonded to a tetrahedral sp hybridized carbon atom in the middle which does not make the π-bonding in
7505-600: The synthetic fibres that followed. Artists of the Arts and Crafts Movement preferred the rich, complex colors of natural dyes, since many natural dye sources contain more than one type of dye compound, unlike synthetic dyes which tend to rely on a single type of dye compound, creating a flatter visual effect. This helped ensure that the old European techniques for dyeing and printing with natural dyestuffs were preserved for use by home and craft dyers. Natural dyeing techniques are also preserved by artisans in traditional cultures around
7600-532: 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
7695-456: The technique of producing a bright red to orange-red dye (known as carthamin ) from the dried florets of safflower ( Carthamus tinctorius ). A bath solution of cold water is first prepared, to which is added the collected flowers. Steeping in cold water releases a yellow pigment ( colorant ) which, after straining, is discarded. After pressing and drying once again the red petals, the petals are re-hydrated again, at which time alkali made from
7790-404: 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. This method of dyeing cotton is declining in importance due to the toxic nature of the chemicals used. Sulfur dyes are inexpensive dyes used to dye cotton with dark colors. Dyeing is effected by heating
7885-537: The ultraviolet region and are colorless to the human eye", "Compounds that are blue or green typically do not rely on conjugated double bonds alone.") In the conjugated chromophores, the electrons jump between energy levels that are extended pi orbitals , created by electron clouds like those in aromatic systems. Common examples include retinal (used in the eye to detect light), various food colorings , fabric dyes ( azo compounds ), pH indicators , lycopene , β-carotene , and anthocyanins . Various factors in
7980-408: The underlying concept in either case being that the cells examined are still alive. In a stricter sense, the term "vital staining" means the polar opposite of "supravital staining." If living cells absorb the stain during supravital staining, they exclude it during "vital staining"; for example, they color negatively while only dead cells color positively, and thus viability can be determined by counting
8075-429: The use of toxic fossil fuel byproducts for their production—in manufacturing and there is a growing demand for products that use natural dyes. Because of their different molecular structure, cellulose and protein fibres require different mordant treatments to prepare them for natural dyes. Cellulose fibres have a lower affinity for natural dyes than do protein fibres. The most common method for preparing cellulose fibres
8170-563: The visible region (some examples are nitro , azo , quinoid groups) and an auxochrome which serves to deepen the color. This theory has been superseded by modern electronic structure theory which states that the color in dyes is due to excitation of valence π-electrons by visible light. Dyes are classified according to their solubility and chemical properties. 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 dye baths. Attachment to
8265-412: The water-soluble alkali metal salt of the dye. This form is often colorless, in which case it is referred to as a Leuco dye , and 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
8360-762: The wool"), after spinning (" yarn -dyed") or after weaving ("piece-dyed"). Many natural dyes require the use of substances called mordants to bind the dye to the textile fibres. Mordants (from Latin mordere 'to bite') are metal salts that can form a stable molecular coordination complex with both natural dyes and natural fibres. Historically, the most common mordants were alum (potassium aluminum sulfate—a metal salt of aluminum) and iron ( ferrous sulfate ). Many other metal salt mordants were also used, but are seldom used now due to modern research evidence of their extreme toxicity either to human health, ecological health, or both. These include salts of metals such as chrome, copper, tin, lead, and others. In addition,
8455-595: The world were derived from indigo dye -bearing plants, primarily those in the genus Indigofera , which are native to the tropics . The primary commercial indigo species in Asia was true indigo ( Indigofera tinctoria ). India is believed to be the oldest center of indigo dyeing in the Old World. It was a primary supplier of indigo dye to Europe as early as the Greco-Roman era. The association of India with indigo
8550-435: The world. The first synthetic dyes were discovered in the mid-19th century, starting with William Henry Perkin 's mauveine in 1856, an aniline dye derived from coal tar . Alizarin , the red dye present in madder, was the first natural pigment to be duplicated synthetically, in 1869, leading to the collapse of the market for naturally grown madder. The development of new, strongly colored aniline dyes followed quickly:
8645-709: Was an important dye for the Asian cotton industry and is still used by craft dyers in Nepal. In tropical Asia, a red dye is obtained from sappanwood ( Biancaea sappan ). In Malaysia and Laos, a red to purple dye is produced from the root of the Indian mulberry ( Morinda tinctoria ). In the Philippines , red dye was obtained from noni ( Morinda citrifolia ) roots, sapang (sappanwood), katuray ( Sesbania grandiflora ), and narra wood ( Pterocarpus spp.), among other plants. Puccoon or bloodroot ( Sanguinaria canadensis )
8740-543: Was especially known for its green dyes. The dyers of Lincoln , a great cloth town in the high Middle Ages , produced the Lincoln green cloth associated with Robin Hood by dyeing wool with woad and then overdyeing it yellow with weld or dyer's greenweed ( Genista tinctoria ), also known as dyer's broom. Woolen cloth mordanted with alum and dyed yellow with dyer's greenweed was overdyed with woad and, later, indigo, to produce
8835-414: Was swiftly displaced by synthetic indigo , which is identical to the natural material and environmentally friendlier as its production did not require hundreds of square kilometers of monoculture . In medieval Europe, purple, violet, murrey and similar colors were produced by dyeing wool with woad or indigo in the fleece and then piece-dyeing the woven cloth with red dyes, either the common madder or
8930-447: Was used in order to selectively kill bacteria in the body. He also used methylene blue to target the plasmodium responsible for malaria . The color of a dye is dependent upon the ability of the substance to absorb light within the visible region of the electromagnetic spectrum (380–750 nm). An earlier theory known as Witt theory stated that a colored dye had two components, a chromophore which imparts color by absorbing light in
9025-485: Was used. Nevertheless, based on the colors of surviving textile fragments and the evidence of actual dyestuffs found in archaeological sites, reds, blues, and yellows from plant sources were in common use by the late Bronze Age and Iron Age . In the 18th century Jeremias Friedrich Gülich made substantial contributions to refining the dyeing process, making particular progress on setting standards on dyeing sheep wool and many other textiles. His contributions to refining
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