To Dye Blue
Boil your material in the solution of alum and tartar already described.
Then make a blue dye by dissolving the prepared indigo paste in water, the quantity of which must depend upon the color you wish to produce. Boil until you have the shade you desire.
The prepared indigo paste is made by dissolving indigo in oil of vitriol and water in a well stoppered bottle, but it is some trouble to prepare, and may be had already made at a dyer’s.
It requires a white ground to produce a good blue.