Indigo is one of the world's oldest and most iconic dyes, traditionally sourced from the leaves of Indigofera tinctoria or related species. Unlike most natural dyes, indigo is not a soluble dye but an insoluble pigment — indigotin — locked inside the plant. This means indigo doesn't bond to fibre the way tannin- or mordant-based dyes do. Instead, it must first be chemically reduced in a vat, converting it into a soluble, pale yellow-green form ("white indigo" or leuco-indigo) that the fibre can absorb. Once the dyed fibre is lifted from the vat and exposed to air, oxidation instantly converts the leuco-indigo back into its insoluble blue form.

Because no mordant is required, indigo can be used on protein and cellulose fibres alike, and it is compatible with a range of vat systems. Depth of colour is achieved through repeated short dips and oxidations rather than a single long soak — each dip adds a thin layer of blue.

GOTS and Eco Dye certified, sourced responsibly from India.