Natural Indigo use may go back as far as four-thousand years from the present day. With the possible exception of iron buff and tannins, indigo has probably seen longer continuous use than any other dye.

Natural indigo is obtained from indigo bearing plants. The most significant one being indigofera tinctoria. This green shrub grows wild and is also cultivated in India, China, Indonesia, and South America.

The plant material does not produce the finished dye, instead it gives a colourless glucose-based substance called indican. When fermented a bacterial enzyme is produced which consumes the glucose and leaves indigotin. At this stage the indigotin (what we know as indigo dye) is insoluble in water. It is at this point that the powder is extracted if it were to be stored or shipped for trading.

Indigo must be chemically reduced prior to dyeing. In its reduced form it is called indigo white and is soluble in water. When fiber is immersed in the indigo dyebath (which is amber to yellowish green) it will be penetrated by the soluble indigo white and a molecular combination accurs. When the fiber is removed from the vat and is exposed to air, the indigo white oxidizes back to the insoluble blue form where it remains in relative permanence.

Indigo was first synthesized in 1880 by Adolph von Bayer. Synthetic indigo is chemically identical to natural indigo and has almost completely replaced it. Synthetic indigo can be made more cheaply than natural indigo, it is more uniform in its concentration, and it dyes more evenly.

Yet there is a magical charm to natural indigo, not the least of which is its amazing history and the wealth of folklore and belief that goes with its use. Some believe that the naturally occuring impurities give natural its own personality and create subtle variations in tone. Natual indigo is much sought after by textile artists.