Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Home › The Art Of Dyeing › To make Indigo Extract
To make Indigo Extract
This is prepared by proceeding exactly as stated for sulphate of indigo and then diluted with about 4 gallons hot water, and the whole put upon a thick woolen filter, over a large vessel, and hot water poured upon the filter, until it passes through nearly colorless; the blackish thoroughly; goods steeped in this should be matter retained upon the filter is thrown covered with the liquor, as pieces exposed away, and the filtered solution is transferred become dry, which deteriorates the fibre; if to a leaden vessel, and evaporated to about 3 left under the liquor the cloth is not hurt by gallons, to which is added about 4 pounds chloride of sodium (table salt) and well stirred; the whole is again put upon a wooden filter and allowed to drain. The extract remains as a thin pasty mass upon the filter, and is ready for use. lon of water add 1 gill of sulphuric acid, stir