The quercitron bark is said to yield from eight to ten times more colour than weld, and about four times more than old fustic; this was, however, Dr. Bancroft's account, who had a strong interest in this dyeing drug, as stated in the first chapter. He also asserts, that one pound of bark with muriate of tin, will dye forty pounds of woollen a bright golden yellow, which afterwards becomes a beautiful and durable scarlet, with a fourth part less cochineal than is usually employed on other occasions for such a colour. But Bancroft did not succeed in doing away the old method of saving tartar and cochineal.
His fullest yellow upon cloth, the author has, however, often tried and found it rich and golden; the process is as follows:
Cloth one hundred pounds; bark in powder, and in a bag, ten pounds; muriate of tin, or murio-sulphate of tin, (for which see forward,) ten pounds. The bark in the bag must be first immersed in the proper sized vessel for six or eight minutes; then add the solution of tin and stir it well for two or three minutes, when the cloth must be put in, and kept in motion by two or three men working over the winch from end to end; then proceed to boil; and, in fifteen minutes boiling, the highest yellow is produced; a longer time would turn the yellow brown.
When a very bright yellow, approaching less to orange, is wanted, seven or eight pounds of solution of tin, five pounds of alum, and ten pounds of bark, will do for a hundred pounds of cloth. In this process, boil the bark first in a bag for a few minutes, then add the solution of tin and the alum, and the cloth afterwards, as before directed; less body requires less quantities of course.
For a full BRIGHT YELLOW delicately inclining to a greenish tinge.
Use eight pounds of quercitron bark, to six of muriate of tin, six pounds of alum, and four pounds of white tartar, for cloth as before. The alum and tartar render the yellow more delicate, and give it more of the lemon or greenish tinge; where this is wanted in the greatest perfection proceed as follows:
Take ten pounds of bark, ten of muriate of tin, or murio-sulphate of tin, ten of alum, and ten of tartar. For cloth three or four times the quantity of the preceding processes may be taken, namely three or four hundred pounds.
In this process the bark must be boiled fifteen minutes in water only, and then the other ingredients be added and mixed in the liquor by stirring. The cloth is next to be put into it, the liquor being first cooled a little; it is then immediately to be turned briskly on the winch till the colour is sufficiently raised.
When a variety of shades are wanted, in working the bark, (contrary to the processes for many other colours) the higher shades should, in this colour, be dyed first, and the weaker afterwards. When about two-thirds of the quantity of the cloth have been dyed, it will be generally found that the liquor, by continuing to extract colouring matter from the bark, has acquired an over proportion, and wants a small quantity of muriate of tin, of alum, and of tartar, perhaps a pound of each, to enable the bark at last, as well as at first, to give the same delicate, pale and greenish tinge. A surer way, however, is to boil the bark in a small quantity of water, separately, for six or eight minutes; and then to add to it the solution of tin, alum, and tartar, and boil them with the bark together for fifteen minutes, and then damp the fire; then have the cloth in a proper sized vessel, supplied with boiling water, and the cloth moving on the winch; after it has gone a few turns round, and is thoroughly wetted out (which it should be before, and now again) lest any part should be dry, add the supplies of the yellow liquor above described, by little and little as they may be wanted: in this way expectation is surpassed by the beauty produced.