Indigo

The tradition of dyeing with indigo, aizome, is centuries old and still continues today. Indigo is the principal dyeing substance used to colour cotton, linen, hemp into rich blues.

The leaves of the small plant, yama ai or mountain indigo, are gathered in summer, watered for 100 days and allowed to decompose. This releases the indigo from the leaves.

The blue-black indigo 'decomposed leaf ball' is placed in a dye vat and dissolved by adding lime.

The dye vats are large, sunk into the ground in sets of four, with a fire hole in the centre to keep the temperature correct.

An active indigo bath is a yellow-green colour; when fabric or threads are immersed, the near-colourless indigo penetrates the material; when removed from the indigo bath, oxidization by the air reveals the classic blue colour.

The depth of colour is governed by the strength of dye and the number of times threads are dipped in the indigo.

Threads are hung out to dry naturally, on bamboo poles in the sun.