- Sustainability -

Indigo





Indigo and indigo dye is an organic compound with a distinctive, brilliant blue colour. It’s probably the most famous of all natural dyes. It is extracted from the leaves of the plant Indigofera tinctoria and related species which grow in tropical climates of India. Indigo is amongst the oldest dyes to be used for textile dyeing and printing with its notoriety stemming back to thousands of years.










The indigo dye year starts in January when seeds of Indigofera are sown by hand in rich soil. The indigo dye seeds germinate in four to five days and the plants grow very rapidly, so there is little need for weeding. No fertiliser is used in the indigo fields as this plant belongs to the legume family and captures atmospheric nitrogen for its growth.

Ninety days later, the indigo dye plants have grown into vigorous shrubs and are half a metre tall. It is now time for the first harvest to begin. The farmers cut the indigo plants with sickles, leaving about 10 cm of plant in the ground. The cut plants are gathered in bundles and the freshly cut leaves are taken for processing nearby where the dye is extracted. By June, the indigo plants have re-grown and it is time for a second harvest and extraction.

During September and October, and sometimes in early November the indigo plants, which have been well watered by the monsoon, are ready for a third and final harvest. Not all the plants are harvested, some are left to flower to produce seeds for the following year.

When the winter rains begin, it is time to prepare the soil for another season. Two-hundred kilos of leaves produces one kilo of indigo. Extracting natural indigo is a lengthy process. The dye is then used for block printing, resist printing, dip dyeing and yarn dyeing. Dyers make the dye by crushing the plant leaves and fermenting them in water. This turns the compound indicant, which is a colourless amino acid, into indigtin, a blue dye. The fermented leaves are then mixed with lye, pressed into cakes, dried over three weeks and, once completely dry, ground into indigo dye powder.







Indigo is a challenging dye because it is not water-soluble. To be dissolved, it must undergo a chemical change called “reduction”. Reduction converts indigo into “white indigo”. When a fabric is submerged into this form of indigo and removed from the dye bath, the white indigo quickly combines with oxygen in the air and reverts to the insoluble, intensely-coloured indigo.

Cotton and linen threads are usually soaked 15-20 times. By comparison, silk threads must be died over 40 times. After dying, the yarn must be sun dried to deepen the colour. More and more Indian designers are patronising this native industry by creating the indigenous dye in the traditional way, thus generating jobs for village-based artisans. It’s because of its high value as a trading commodity that indigo was often referred to as Blue gold.

          


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