INDIGO DYES

Most jeans are colored in the characteristic blue indigo color. Indigo is among the oldest dyes used for textile dyeing and originates from the Indigo Ferrer plant.

Indigofera tinctoria, also called?true indigo, is a species of plant from the?bean family?that was one of the original sources of?indigo dye. It has been naturalized to tropical and temperate?Asia, as well as parts of?Africa, but its native habitat is unknown since it has been in cultivation worldwide for many centuries. Today most dye is synthetic, but?natural dye?from?I. tinctoria?is still available, marketed as natural coloring where it is known as?tarum?in Indonesia and?nila?in Malaysia. In Iran and areas of the former?Soviet Union?it is known as?basma. The plant is also widely grown as a soil-improving?groundcover.

True indigo is a shrub one to two meters high. It may be an?annual,?biennial, or?perennial, depending on the climate in which it is grown. It has light green?pinnate?leaves and sheafs of pink or violet flowers. The plant is a?legume, so it is rotated into fields to improve the soil in the same way that other legume crops such as?alfalfa?and?beans?are.

Dye is obtained from the processing of the plant's leaves. They are soaked in water and?fermented?in order to convert the?glycoside?indican?naturally present in the plant to the blue dye?indigotin. The precipitate from the fermented leaf solution is mixed with a strong base such as?lye.

The?rotenoids?deguelin,?dehydrodeguelin,?rotenol,?rotenone,?tephrosin?and?sumatrol?can be found in?tinctoria.

Marco Polo?(13th century) was the first European to report on the preparation of indigo in India. Indigo was quite often used in European easel painting, beginning in the Middle Ages.

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Reference: https://en.wikipedia.org/wiki/Indigofera_tinctoria

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