Staining of LINEN. Linen receives a black colour with much more difficulty than woollen or cotton. The black struck on linen with common vitriol and galls, or logwood, is very perishable, and soon washes out.—Instead of the vitriol, a solution of iron in four strong beer is to be made use of. This is well-known to all the calico-printers; and by the use of this, which they call their iron-liquor, and madder root, are the blacks and purples made which we see on the common printed linens. The
Linen The method of making this iron liquor is as follows; A quantity of iron is put into the four strong beer; and, to promote the dissolution of the metal, the whole is occasionally well stirred, the liquor occasionally drawn off, and the rust beat from the iron, after which the liquor is poured on again. A length of time is required to make the impregnation perfect; the solution being reckoned unfit for use till it has stood at least a twelve-month. This solution stains the linen of a yellow, and different shades of buff-colour; and is the only known substance by which these colours can be fixed in linen. The cloth stained deep with the iron-liquor, and afterwards boiled with madder, without any other addition, becomes of the dark colour which we see on printed linens and cottons; which, if not a perfect black, has a very near resemblance to it. Others are stained paler with the same liquor diluted with water, and come out purple.
Linen may also be stained of a durable purple by means of solution of gold in aqua regia. The solution for this purpose should be as fully saturated as possible; it should be diluted with three times its quantity of water; and if the colour is required deep, the piece, when dry, must be repeatedly moistened with it. The colour does not take place till a considerable time, sometimes several days, after the liquor has been applied: to hasten its appearance, the subject should be exposed to the sun and free air, and occasionally removed to a moist place, or moistened with water.—When solution of gold in aqua regia is soaked up in linen cloths, the metal may be recovered by drying and burning them.