Indigo is among the oldest dyes to be used for textile dyeing and printing. Many Asian countries, such as India, China and Japan have used indigo as a dye for centuries. The dye was also known to ancient civilisations in Iran, Egypt, Peru and Africa. In ancient times, indigo was often referred to as ‘blue gold’ because of its high value as a trading commodity.
A variety of plants have provided indigo throughout history, but the most natural indigo was obtained from those in the genus Indigofera, which are native to the tropics. Indigofera belongs to the legume family and over three hundred species have been identified. Indigofera tinctoria (also known as true indigo, as it was one of the original sources of indigo) is the most common.
Pop your safety goggles and lab coat on…we’re delving into the chemical make up of indigo!
The precursor to indigo is indican, a colourless, water-soluble organic compound. Indican readily hydrolyses to release β-D-glucose and indoxyl. Oxidation by exposure to air converts indoxyl to indigo. Indican is obtained from the processing of the plant's leaves. The leaves are soaked in water and fermented to convert the indican 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 then pressed into cakes, dried, and powdered. The powder is then mixed with various other substances to produce different shades of blue.
Natural Indigo dyeing is a universal practice. It starts with the harvesting of the plant, then the extraction of the pigment, next comes the preparation of the dye bath and finally dyeing of the cloth or yarn. The weaver/tailor/embroider transforms the dyed cloth into garments or homewares of sublime beauty. To further your journey into the world of Indigo, we highly recommend getting your hands on Catherine Legrand’s gorgeous coffee table book ‘Indigo: The colour that changed the world’.
Confession: We are a little bit obsessed with indigo at Loomology..just look at our indigo dye ‘splat’ that features in our logo! If you are also a lover of traditional indigo dyed textiles, you can shop our Sublime Indigo mini frame, which was created by renowned master dyer Aboubakar Fofana in his Bamako workshop in Mali, Africa.
Japanese indigo textiles. Image via Pinterest, original source unknown.
Freshly indigo dyed textiles drying in the Bagru sun. Image by Loomology.