Meeting report: Indigo — a Blue to Dye For

Date: 
18 November 2011
Speaker(s): 
Valerie Reilly

Indigo, a Blue to Dye For was the topic of Valerie Reilly's talk to Dumfriesshire and Galloway Natural History and Antiquarian Society. Having served for 35 years in Paisley Museum, from which she has now retired, she is very knowledgeable about dyes and Paisley shawls.

In a lively and well-presented illustrated discourse Valerie covered every conceivable aspect of the story of indigo, which touches more spheres of human activity than most people realise — trade, industry, furnishings, clothing, medicine, veterinary products, agriculture, science, the arts, cosmetics, etc.

Listed in the seven colours of the rainbow, it is placed between blue and violet. India, believed to be the oldest centre of indigo dyeing in the world, was also an important supplier of indigo dye, obtained from the plant Indigofera tinctoria. The name is derived from the Greek word indikon; the Latin term is indicum and hence indigo in English. The Sanskrit term is neel; anyle or indico are also used interchangeably.

The dye was in use in the third millennium BC. Historically blue colours have been revered: in Egypt, for example, Tutankhamun's funerary apparel displayed it; likewise Inca textiles in South America. As it required several pounds of indigo from another source, Murex trunculus, for each dyeing, indigo-dyed textiles were associated with wealth. Wools for much-prized Persian carpets are still being produced by ancient processes. The ancient dye pits in Karo in Nigeria are still in use today.

Marco Polo, the explorer described indigo industry at Kerala in India in 1298. Gradually the cultivation of indigo-producing plants spread westwards, although efforts were made to confine it to Islamic areas by the Ottoman Empire.

By the 13th Century many in Europe made their livelihood producing woad, which had been another source of the dye since the Hellenistic period from about 323BC to 31BC. Woad, Isatis tinctoria, was being grown in southern England in Anglo-Saxon times but such was the demand that extra quantities still had to be imported. It was being grown around Haddington in 1693, but only for local use. The dyers were the most prosperous of all those involved in the textile trade. Woad was being added to indigo for tunics. Woad-dye waste was a pollutant.

An involved but very profitable shipping trade, promoted by the English East India Company, founded in 1600, grew up. Asian indigo-dyed textiles or supplies of indigo itself (whose suppliers were guilty of adulteration) were exported to Europe, cloth was then taken to Africa and exchanged for slaves. The on-going ships were bound for America and/or the Caribbean, where the new cargo might be indigo or sugar, destined also for Europe. This trade was vulnerable to piracy, insect damage or earthquake.

To produce the dye leaves are added to water and ash to start fermentation. The task of manual oxygenation, dangerous to health, was usually done by slaves; in time, with the spread of industrialisation, mechanised paddles came to be used. A paste is produced for local use, but it had to be dried off into balls for transporting long distances. In 1501 there is a case of a ship leaving Bordeaux and being attacked by pirates. Some of the balls of indigo seized landed up in Kirkcudbright!

The loss to Britain of the American colonies in 1783 led to India becoming the main source of indigo, huge quantities of which were required for military uniforms. The following export figures are very revealing: in 1782 when indigo was still coming from Central America exports from India amounted to only 25,000 lbs; in 1795 they stood at 4,368,000 lbs; and in 1815 at 7,650,000 lbs.

The first synthetic indigo dye, mauveine, was invented by William Perkin. The trade in it expanded rapidly from about 1930. Rivalry between natural and synthetic dyes ensued: cost was usually the determining factor. The popularity of denim has preserved the indigo trade. The invention by Jacob Davis and Levi Strauss in 1873 of the pop-rivet to stop wear on the pockets gave impetus to the production of jeans. Their adoption by the late James Dean in the film Rebel Without a Cause has ensured them an undying place in fashion history!