Production of indigo concentrate from wood in high yield useful for producing dye e.g. for textile, paper, paint or glaze

摘要

The production of indigo concentrate from the constituents of woad comprises: (a) placing the freshly harvested, whole leaves in a mixer; (b) adding warm water at 25 deg C at a rate of 1 kg leaves to 10 l water; (c) hydrolysing the mixture for about 20 hours; (d) removing the leaves from the liquid; (e) alkaline precipitation of indigo from the remaining water; (f) repeated washing; and (g) drying.