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 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, after spinning or after weaving. Many natural dyes require the use of substances called mordants to bind the dye to the textile fibres. Mordants 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 and iron. 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, a number of non-metal salt substances can be used to assist with the molecular bonding of natural dyes to natural fibreseither on their own, or in combination with metal salt mordantsincluding 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 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, indigo, saffron, and madder were important trade goods in the economies of Asia, Africa and Europe. Dyes 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.
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 dyeswhich require the use of toxic fossil fuel byproducts for their productionin manufacturing and there is a growing demand for products that use natural dyes.

Dyes in use in the fashion industry

Because of their different molecular structure, cellulose and protein fibres require different mordant treatments to prepare them for natural dyes.
  • Cellulose fibres: cotton, linen, hemp, ramie, bamboo, rayon
  • Protein fibres: wool, angora, mohair, cashmere, silk, soy, leather, suede
Cellulose fibres have a lower affinity for natural dyes than do protein fibres. The most common method for preparing cellulose fibres is to use a tannin first, 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:

Animal-derived dyes

  • Cochineal insect
  • Cow urine
  • Lac insect
  • Murex snail
  • Octopus/Cuttlefish

    Plant-derived dyes

  • Black walnut or black walnut hulls
  • Catechu or cutch tree
  • Gamboge tree resin
  • Chestnut hulls
  • Ebony leaves
  • Himalayan rhubarb root
  • Indigo leaves
  • Kamala seed pods
  • Katuray
  • Madder root
  • Mangosteen peel
  • Narra wood
  • Myrobalan fruit
  • Noni roots
  • Pomegranate rind
  • Sappanwood
  • Teak leaf
  • Sumac or staghorn sumac tree
  • Turmeric roots
  • Weld herb

    Origins

Colors in 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, were found. Polychrome or multicolored fabrics seem to have been developed in 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.
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 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 the dyeing process and his theories on color brought much praise by the well known poet and artist Johann Wolfgang von Goethe.

Processes

After mordanting, the essential process of dyeing requires soaking the material containing the dye in water, adding the textile to be dyed to the resulting solution, and bringing the solution to a simmer for an extended period, often measured in days or even weeks, stirring occasionally until 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 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, or the mordant may be incorporated in the dyebath, or the mordanting may be done after dyeing.
Natural alum has been the most common metallic salt mordant for millennia, but tin, copper, iron and chrome 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 dyeing to protect fibre structure, shift pH to achieve different color results, or for any number of other desirably outcomes. Metal-salt accumulating plants 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 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 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 along with 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.

Common dyestuffs

Reds and pinks

A variety of plants produce red dyes, including a number of lichens, henna, alkanet or dyer's bugloss, asafoetida, sappanwood, various galium species, and dyer's madder Rubia tinctorum and Rubia cordifolia. Madder and related plants of 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 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 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 is native to the Himalayas and other mountains of Asia and Japan. Munjeet 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. In Malaysia and Laos, a red to purple dye is produced from the root of the Indian mulberry. In the Philippines, red dye was obtained from noni roots, sapang, katuray, and narra wood, among other plants.
Puccoon or bloodroot 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 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.