Indigo

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by Caroline Stone

Indigo is a blue dye extracted from several different species of plant, in particular Indigo tinctoria L. in tropical regions, Isatis tinctoria L. (woad) in Central and Northern Europe, and Polygonum tinctorium in China and Japan. Until c. 1900 it was the most used dye in the world and for millennia was a major item of international trade and a very important cash crop.

Our name for the dye comes from the Greek: indikon, showing that it was originally an import from India. The Sanskrit word, however, is nila and under this name it has passed into Arabic — nil, or with the article, an-nil — and from Arabic to other languages, such as Spanish, which has añil, "dark blue".

The earliest surviving textiles woven with indigo are mummy cloths with narrow blue striped borders (c.2400-2000 B.C.) from Deir el-Bahri, Egypt. This was probably indigenous woad, although it has been argued that indigo traded from South Arabia or India may have been used. There is also a possibility that indigo dyeing dates back as far as 6000 B.C. at Çatal Huyuk in Anatolia.

There are numerous reasons for the popularity of indigo. It is a dye that can be used on all kinds of textiles, requires no mordant, and does not weaken the fabric. The dyeing process, although laborious, is reliable; tropical indigo, in particular, being relatively colour-fast. Again, in early times, indigo was used both to dye blue and, with madder, to imitate the priceless royal purple of the murex, a colour often forbidden to commoners. It was also used with yellow to give green and by repeated dipping could produce a near black. Finally, although expensive, indigo was less so than many other dyes.

Trading patterns were very complex. The dye was often sent to areas that produced an indigenous blue dye, but one which was considered to be inferior. This was particularly true when indigo took over from woad in 16th century Europe. The innovation gave rise to much conflict and in an effort to protect local farmers the use of indigo at one stage carried the death penalty. Again, the production of indigo in Guatemala had serious repercussions throughout the European and Asian markets.

Indigo-dyed cloth was also a major export. Here again, it was traded in all directions, since different areas were anxious to exchange specialties. Thus, the famous blue and yellow ikats of Yemen (perhaps the striped cloth praised by the Prophet Muhammad in a well-known hadith) could have been exchanged for Indian block printed cottons or tapestry-weaves from Egypt.

In many areas, indigo was not only considered to give cloth a pleasant colour, but was also held to have protective powers. This was particularly true of the Tuareg, "the Blue Men" of the western Sahara, in Yemen, or among the Miao of south-west China. The staining of the skin which resulted from wearing deep-dyed and burnished indigo cloth was held to be beautiful, health giving and auspicious. At an earlier date, the Romans had commented with surprise on the British custom of painting themselves with woad.Indigo was also used as a hair-dye, in cosmetics, for medicinal purposes, in tattooing and as a pigment for painting and for colouring paper. Originally, this latter use seems to have been reserved in both east and west for sacred texts.

Indigo often had a ritual significance. In some areas, such as Upper Egypt and Central Asia, the colour was used for mourning, while tablets of indigo dye appear as part of a dowry in 19th century Tunisia.

Indigo began as a luxury product and gradually came to be the colour associated with work clothes. About 1900, synthetic indigo, one of the first aniline dyes, was beginning to take over from plant indigo— it was cheaper, much less laborious to use and needed no skill. By the middle of the 20th century it was being used on an enormous scale for denim jeans in the West and "Mao suits" in China.

Real indigo has almost vanished, except in certain areas of Africa, South East Asia and remote regions of China. It is being revived, however, for the production of luxury craft textiles, for example in Japan. The wheel has come full circle.