6oo

DYEING AND CALICO PRINTING.

incorporated with each other. After this mixture has been printed on thecalico, the adtion of the steam, like that of boiling water in woollen-dyeing,effects the combination between mordant, colour, and fibre. The finest effedtsin this style are obtained by preparing the cloth first with a tin mordant, so asto fix peroxide of tin in the fibre. In case of woollen and worsted goods,indeed, this “ preparing,” as the operation is technically called, is absolutelynecessary for the production of good colours. The peroxide of tin thus depo-sited in the fibre adts not only as a mordant, but it helps in neutralising theacidity of many steam-colours, and aids thus in the formation of sub-salts—or basic compounds—which combine most readily with colouring matters.The methods of “preparing” in different print-works vary greatly, accordingto the judgment of the proprietor, the kind of cloth operated upon, and theeffects intended to be produced. The article generally used is, however, thestannate of soda, often known in the trade, in consequence, as u alkalinepreparing salts.”

Calicoes are frequently prepared as follows :—The pieces, stitched togetherby their ends, are padded, with a machine with wooden rollers, in a solutionof stannate, at io° Tw. This process is repeated twice, with the interval ofan hour, during which the pieces are allowed to remain wet. They are thenwinced through diluted sulphuric acid, at i|° to 3 0 Tw.; winced again in purewater, and washed. The washing must be merely sufficient to remove freesulphuric acid. After this operation the pieces are unstitched, freed fromexcess of water in the hydro-extraCtor, and carefully dried at a steam-heat.

As a prepare for heavy shades the following procedure is in use :—Thepieces are padded in stannate, at 24 0 Tw.; left wet for about two hours;winced in dilute sulphuric acid (technically called “vitriol sours ”), at 6° Tw.;washed and partially dried in the hydro-extradtor. These operations are allrepeated once more, in the same order, and the pieces are then dried. Theacid liquid, of course, soon becomes reduced in strength, from the amount ofalkali neutralised—a point which requires constant attention, since, if the“ sours ” be not kept up to the proper pitch, the tin deposited on the fibre willwash off, and the work will be quite irregular.

Some printers use, along with the stannate of soda, arsenical compounds,and also the tungstate of soda. See chapter on Mordants, pp. 534 and 542.

The following steam-colours are in common use:—

No. 1. Steam-Black , for Cylinder-work .—

Logwood extradt, at 12 0 Tw. 1 gal.

Gall liquor, at g° Tw. 1 quart

Mordant (see below). 1 „

Flour . 2 lbs.

Starch . 6 ozs.

The whole is boiled for ten minutes, and mixed with £ pint nitrate of iron.The mordant above mentioned consists of—

Acetic acid. 1 quart

Acetate of copper . i£ quarts

Iron liquor, at 24 0 Tw. i> ,,

Red liquor, at 20° Tw. . 1 quart.