The Dyer's Guide / Being a compendium of the art of dyeing linen, cotton, silk, wool, muslin, dresses, furniture, &c. &c.; with the method of scouring wool, bleaching cotton, &c., and directions for ungumming silk, and for whitening and sulphuring silk and wool; and also an introductory epitome of the leading facts in chemistry, as connected with the art of dyeing

by Thomas Packer

To dye silk LILAC.

Lilac is and should be a bright light shade of violet or purple; to give it the blue requires great management. The vats being generally too strong, it is best to mix a little of the new rich vat with some pearl-ash in clean cold water, and so prepare a liquor on purpose, by which the lilacs may be blued or reddened at pleasure. When this liquor is first mixed it becomes of a green colour; the silks therefore should not be dipped till the liquor begins to lose its green colour and inclines to blue. Pearl-ash added to this liquor helps to blue the archil, because the effect of the alkali upon red is to render it violet.