Madder reds are sometimes rosed, as it is called, with archil and brazil wood. In this way they become more beautiful and velvety, but the brightness thus given is not permanent.
When sulphate of copper is employed as a mordant, the madder dye yields a clear brown, somewhat inclined to a yel low; when solution of tin is used, the tint, according to Berthollet, is somewhat brighter than that obtained by the com mon method, but is always more inclined to yellow or fawn colour.
The red procured from kermes is finer than that from madder. The kermes is an insect found on a small species of live oak, in Languedoc, Spain, Portugal, and other places ; the females alone are used, they are of the shape and size of a pea, and 4 a reddish brown colour.
To dye woollen yarn with kermes, it is first boiled half an hour in water with bran ; then two hours in a fresh bath, of one fifth of Roman alum, and one tenth of tartar dissolved in sour water ; after this, it is left in a linen bag for some days.in a cool place. To obtain a full colour, as much kermes as equals three fourths, or even the whole of the weight of the yarn, is put into a warm bath, and the wool is put in at the first boiling. As cloth is less dense than wool, either spun or in the fleece, it requires one fourth less of the salts in boiling, and of the kermes in the bath The scarlet made by kermes was called scarlet in grain, from the insect resem bling a grain ; it has much less bloom than that procured from cochineal ; but is more permanent, and spots of grease may be discharged from it without injury. Since the art of heightening the colour of cochineal by solution of tin has been dis covered, kermes has not been much used. The scarlet produced by the prepara tion of cochineal just mentioned is es teemed the finest and most splendid of any. Cloth to be dyed with it is first sub mitted to the following bath : six pounds of tartar are infused in the water made warm, for every hundred pounds of the cloth ; the bath is then stirred briskly, and when the heat has increased a little more, half a pound of powdered cochi neal is to be added, and the whole is then to be well mixed ; immediately after wards, five pounds of a very clear solu tion of tin are to he poured in, and care fully mixed. 'When the bath begins to
boil, the cloth is introduced, and briskly moved for two or three turns, after which it is moved more slowly. The boiling hay. ing continued for two hours, the cloth is taken out, exposed to the air, and carried to the river to be well washed.
The cloth is afterwards passed through a second bath for the reddening ; to pre pare which, the boiler is to be first emp. tied, and again filled with water ; and when this has just reached the boiling point, five pounds and three quarters of cochineal, powdered and sifted, are to be added. These are to be well mixed; and some time afterwards, when a crust that forms on the surface opens of itself in several places, 13 or 14 pounds of solution of tin are poured in. Should the bath after that rise above the edge of the boil er, it may be cooled with a little water. The bath being well mixed, the cloth is put in, and turned quickly two or three times. It is then boiled in the bath for an hour, taking care to keep it under the surface. It is afterwards taken out, ex posed to the air, and, when cool, washed in the river, and dried.
Some dyers do not remove the cloth out of the first bath; but merely refresh it, and perform the operation of redden ing in the same bath. In this method, the infusion of cochineal, made in a separate vessel, and mixed with a proper propor tion of tin, is added. By conducting the process in this way, the scarlet is suppos ed to be equally fine, and there is a considerable saving of time and fuel, To give scarlet the bright lively red, called lire colour, a yellow tinge is com municated to the cloth by boiling fustic in the first bath, or by adding a little tur meric to the cochineal. A larger propor tion of the solution of till also produces this yellow shade, but it renders the cloth harsh, and limits he action of the colour ing matter.