Dyestuffs

David S. Seigler Department of Plant Biology University of Illinois Urbana, Illinois 61801 USA seigler@life.illinois.edu http://www.life.illinois.edu/seigler

Dyestuffs from plants - Outline Importance o Former o Today Botanical Chemical Indigo Madder

Mordants Special uses o Food o Laboratory use o Cosmetics o Tattoos

Reading CHAPTER 15 IN THE TEXT, 372 ff.

Introduction Dyeing of fibers has been carried out since antiquity. Virtually every culture has its own set of dyestuffs, but a few have emerged and have been particularly important.

Although these dyes were once widely used, the synthesis of synthetic dyestuffs in 1856 by William Perkin, an English chemist, and the subsequent manufacture of synthetic dyes (mainly by the Germans), replaced almost all of natural dyes with better quality materials. Synthetic dyes are more stable, many bind more effectively to the fabrics, and they are more reproducible. Some purists still use natural dyes, but except for food and histological uses, few of them are important.

Silk dress dyed with synthetic mauve Chemistry in Britain

Several dyes from animals have also been used Several dyes from animals have also been used. Cochineal (Coccus cacti) is a scale insect that feeds on cacti. It was used by the Aztecs. A related insect from the Middle East produces a similar dye called kermes.

Scale insect on Opuntia species

Scale insect and effects of mashing them

Adherence of dyes Dyes must adhere to the fibers or they will be washed out. It is easier to dye animal fibers than plant fibers. Although many plant parts are colored, the components of some of these parts are not particularly stable and decompose too quickly to be useful. Some do not bind well to the fibers. In some cases, the dyestuffs bind tightly by chemical bonding and in others they are only bound by hydrophobic interactions.

Mordants As early as the Egyptians, it was known that other substances caused some dyes to bind that normally would not. These are called mordants. Many mordants are metal salts that appear to form metal bridges between the dye and the fiber molecules.

Sometimes mordants came from the container in which the dyeing was being done and at other times from dung, urine or other compounds added. Some dyestuffs (such as madder) contain substances that naturally act as mordants. Alum is a commonly used mordant. Cream of tartar, wood ashes, tannic acid (sumac), and many other substances have been used.

Woad, Isatis tinctoria, Brassicaceae Woad (Isatis tinctoria, Brassicaceae or Cruciferae) was once widely grown and utilized as a dyestuff in Europe. Woad contains a smaller amount of the same compounds as found in indigo (actually these compounds are found in a number of other plants as well).

Woad, Isatis tinctoria, Brassicaceae

The odors produced from processing woad were legendary The odors produced from processing woad were legendary. The leaves were crushed and made into balls which were then allowed to ferment. After fermentation, the product was allowed to dry and then refermented before use to make it soluble. In the Middle Ages, woad was a common article of commerce in Europe.

Indigo (Indigofera tinctoria, Fabaceae) Indigo (Indigofera tinctoria, Fabaceae) has been one of the most important dyestuffs; this dye was used as far back as 6000 years in China. Indigo produces an intense deep blue color. The leaves and branches of the plant are harvested, placed in a vat, covered with water, and permitted to ferment.

Indigo, Indigofera tinctoria, Fabaceae R. Bentley and H. Trimen, Medicinal Plants, London, Churchill, 1880

Indigo, Indigofera tinctoria, Fabaceae Courtesy Dr. David Rembert

The sludge of partially rotted plant material which settles to the bottom is collected and pressed into cakes. When dry, these cakes produce a powder that makes a colorless solution. The color only develops when an item is dipped into the solution, removed and then exposed to air. See p. 375.

Submerging indigo foliage under water to manufacture indigo http://www.indiamart.com/nccagroindustries/

Indigo dye ready to be added to the dye bath P. C. Cross, The indigo dyers of Amarapura, http://www.tribaltextiles.info/Galleries/Amarapura_Indigo_Dyers.htm

When the fabric is first removed from the bath of indigo dye, it is not blue, but turns blue upon oxidation by air.

Indigo dyeing and the cultivation of the plant originated in India Indigo dyeing and the cultivation of the plant originated in India. Because of the good quality of the dye, indigo became an important item of trade between India and other parts of the world by 300 B.C. Dyers in Europe tried to resist the importation of indigo into Europe and were able to do so for a long time. Finally, however, quality won out.

Indigo was an early crop in colonial South Carolina Indigo was an early crop in colonial South Carolina. South Carolina indigo was considered excellent, but as the economics were not too good, it was replaced by rice. The leaves contain about 3% indigo. Synthetic indigo was produced in 1897.

Although indigo of commerce came from an Old World plant, another species of Indigofera was domesticated and used as a source of a blue dye by the Precolumbian inhabitants of Yucatan.

Baptisia leucantha, false indigo, Fabaceae In the Eastern U.S., Indians sometimes used Baptisia species, which also contain indigo, as dyestuffs.

Madder (Rubia tinctoria, Rubiaceae) Madder (Rubia tinctoria, Rubiaceae) (see p. 372) has been used since ancient times. One form of this dye is sometimes called Turkey red. The dyestuff is found in the root of the plant. The compound in the plant is ruberythric acid. Alizarin (a compound derived from madder) is usually used with an aluminum mordant.

Madder is locally important in the Near East and indigo is still used in Africa and India.

Madder (Rubia tinctoria, Rubiaceae)

This dyestuff is fast to water and light. Madder was formerly used to dye mummy blankets in Egypt. Although the dye is fast, the dyeing process is complicated. The fibers were covered with cheap vegetable oil (called Turkey red oil), were then degreased and treated with tannic acid, followed by a aluminum mordant. The fibers were then steamed.

Wool dyed with madder

Changing the mordant can give red, pink, lilac, orange, black, and brown colored pigments. This dye was introduced into Europe in the late Middle Ages. The Dutch selected lines that were of superior quality. The color of the British soldier's uniform in the Revolutionary War was produced by madder. Alizarin is still used as a biological stain.

Henna (Lawsonia inermis, Lythraceae) By 3000 B.C., Greek women used henna (Lawsonia inermis, Lythraceae) to dye their hair. The leaves are ground into a paste that has a great affinity for protein. Henna is still used in hair preparations.

Coutesy Dr. Anita Brinker Dyeing the skin with henna is practiced in many Near Eastern countries. Coutesy Dr. Anita Brinker

Swissair Gazette

Safflower (Carthamus tinctorius, Asteraceae or Compositae) Safflower has been used as a dyestuff for thousands of years in India and other parts of the Near East. Probably native to Afghanistan and Pakistan. Makes a red or yellow fugitive dye. Today grown mostly as an oilseed.

Safflower (Carthamus tinctorius, Asteraceae or Compositae)

Logwood (Haematoxylon campechianum, Fabaceae) Logwood (Haematoxylon campechianum, Fabaceae) came from the New World. The wood of this tree permitted dyeing things black for the first time. Although not used today for dyeing, haematoxylon stain is used as a histological stain in blood analysis.

Logwood (Haematoxylon campechianum, Fabaceae)

Logwood (Haematoxylon campechianum, Fabaceae)

Achiote or annatto, Bixa orellana, Bixaceae Achiote or annatto, Bixa orellana, Bixaceae, was used by the Aztecs and Mayans for food preparation. The plant is probably native to Brazil. The pulp surrounding the seeds contains a lipid dye that is soluble in grease and dyes foods a yellow-orange-red color.

Achiote is widely used in Latin America, but also in other parts of the world today. This substance is also now used to dye margarine and similar products. See p. 374. Achiote contains about 2% vitamin A.

Achiote or annatto, Bixa orellana, Bixaceae

Achiote or annatto

Litmus dye comes from the lichen Rochella tinctoria Litmus dye comes from the lichen Rochella tinctoria. The pigment from this lichen has been used for pH measurement.

Turmeric (Curcurma longa, Zingiberaceae) is used mostly today to color foods (such as pickles), but has been used to dye clothing.

Genipapo, Genipa americana, Rubiaceae

Genipapo, Genipa americana, Rubiaceae Genipapo or genipa was used to paint the bodies of many Central and South American Indian groups. The fruit also is eaten.

Batik dyeing in Indonesia

Stamping designs on cloth with lightly colored wax. Dyeing the part of the cloth that is not waxed.

Heating the cloth to set the dye and to remove the wax

Applying a second or third coat of wax before redyeing the cloth.

Making the presses for applying wax.