Part 2 of making precipitated indigo: circulate the liquid with a small pump, observe the foam, settle the pigment and remove the clear upper liquid to obtain indigo paste.
First-cut Japanese indigo is fermented in water for three days, then slaked lime is added before vigorous agitation begins.
A step-by-step method for soaking Japanese indigo leaves, adding slaked lime, agitating the liquid and settling the pigment for storage.
Japanese indigo is strained after soaking, mixed with slaked lime and agitated. The pigment settles into indigo paste, which is dried and powdered.
A dried cake made from home-produced precipitated indigo is reduced with caustic soda and sodium hydrosulfite, then used to dye and oxidise cloth.