II. Steam colours upon silk.—The same plan of operations may be adopted here as is described for calico-printing; the main difference being in the method of mordanting the stuffs. After boiling in soap water, in the proportion of 4 ounces per pound of silk, the goods are washed in cold water, and then in hot water at 140°; they are next rinsed, passed through weak sulphuric acid, rinsed, squeezed between rollers, and afterwards steeped in a bath containing 8 ounces of alum per gallon, where they remain for four hours, with occasionally wincing. They are now rinsed, and dried. The subsequent treatment resembles that of steam-colour printed cottons.
Black.—Take a gallon of decoction, made with 4 libs. of logwood, with which
Black.—14 ounces of starch are to be combined: mix in
Black.—2 ounces of powdered nut-galls: boil, and pour the colour into a pipkin containing
Black.—2 ounces of tartaric acid; 2 ounces of oxalic, both in powder, and
Black.—2 ounces of olive oil. Stir the colour till it is cold, and add
Black.—8 ounces of nitrate of iron, and 4 ounces of nitrate of copper.
The red, violet, lilac, yellow colours, &c. are the same as for steam colours upon cotton. Topical colours are also applied without mordanting the silk beforehand. In this case a little muriate of tin is introduced. Thus, for
Yellow.—Take 1 gallon of a decoction, made with 4 libs. of Persian berries: dissolve in it 8 ounces of salt of tin (muriate), and 4 ounces of the nitro-muriatic solution of tin. Thicken with 2 pounds of gum.
Printing of foulard pieces. The tables which serve for the impression of silk goods are so constructed as to receive them in their full breadth. Towards the part between the colour or sieve tub and the table, the roller is mounted upon which the piece is wound. This roller, A B, [fig. 246.], has a groove, C, cut out parallel to its axis. Into this a bar is pressed, which fixes the end of the piece. The head, B, of the roller is pierced with several holes, in which an iron pin passes for stopping its rotation at any point, as is shown at B. At the other end of the table there is placed a comb, [fig. 247.], which is supported by pivots A B at its ends. The teeth of the comb are on a level with the cloth.
The piece is arranged for printing as follows:—It is unwound, and its end is brought upon the teeth of the comb, and made to pass into them by slight taps with a brush. It is now stretched, by turning round the roller, and fixing it by the pin-handle. After tracing the outline, the printing blocks are applied. Care should be taken, in the course of printing, always to fix the teeth of the comb in the middle line between two handkerchiefs. The operation of grounding-in is much facilitated by this plan of extension.
The pieces are washed in running water, and must be rapidly dried. The subsequent dressing is given by gum tragacanth: they are dried upon a stretching frame, and then folded up for the market.
III. Mandarining of silk stuffs and chalys.—This style of printing depends upon the property which nitric acid possesses of giving to silk and woollen stuffs a yellow colour.