Applied chemistry : in manufactures, arts, and domestic economy / edited by Edward Andrew Parnell.

  • Parnell, Edward A. (Edward Andrew)
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Applied chemistry : in manufactures, arts, and domestic economy / edited by Edward Andrew Parnell. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    the unmordanted portions the color is feebly attached, so that it may be wholly removed by washing either in soap and water, in a mixture of bran and water, or in a dilute solution of chloride of lime. 2. Topical Style, for Steam and Topical Colors.—Such coloring matters as are incompletely, or not at all, precipitated from their solutions on being mixed with certain solutions of a mordant, are sometimes printed on the cloth with the mordant, and the fixation of the color is afterward effected by exposing the cloth to steam. Some coloring matters applied topically in a state of solution become firmly attached to the cloth without a mordant and without the process of steaming, but merely by drying with exposure to the air. 3. For Mineral Colors (Padding Style).—To produce a figure in a mineral coloring material the cloth may be first printed with one of the two saline solutions, and be afterward uniformly impregnated with the other. To obtain a ground of a mineral color, one or both of the solutions may be applied by the padding machine. 4. Resist Style.—In the processes referable to the resist style, the white cloth is first imprinted with a substance called the resist, or resist paste, which has the property of preventing those portions of the cloth on which it is applied from acquiring color when afterward exposed to a dyeing liquid. Resists are divisible into two classes ; one is employed to prevent the attachment of a mordant, and the other that of a coloring matter. 5. Discharge Style.—The object of the processes belonging to this style of work is the production of a white or colored figure on a colored ground. This is effected by applying topically to the cloth already dyed or mordanted, a substance called the discharger, which has the property of decomposing or dissolving out either the coloring matter or the mordant. Chlorine and chromic acid are the common discharging agents for decomposing a vegetable or animal coloring matter, and an acid solution for dissolving a mordant. 6. For China Blue.—This is a very peculiar style, and is practised with one coloring matter only, namely, indigo. This pigment is printed on the cloth in its insoluble state, and is dissolved and transferred to the interior of the fibre by the successive application of lime and copperas, with exposure to the air. The topical application of the coloring matter, mordant, discharge, or resist, may be made by five different methods:— 1. The simplest is by means of a wooden block, of from nine to twelve inches in length, and from four to seven inches in breadth, bearing the design in relief as an ordinary woodcut; or, when the design is complicated, and a very distinct impression is required, the figure is sometimes formed by the in- sertion of narrow slips of flattened copper wire, the interstices being filled with felt. The block is worked by the hand, and is made of sycamore, holly, or pear-tree wood, on a substratum of some commoner kind of wood. It is charged with color or mordant by pressing it gently on a piece of superfine woollen cloth, called the sieve, which is kept uniformly covered with the thickened coloring matter or mordant by an attendant boy of girl, called the tearer (corrupted from the French word tireur), who takes the color up by a brush from a small pot and applies it evenly to the woollen cloth. This cloth is stretched tight over a wooden drum, which floats in a tub full of old paste or thick mucilage to give it sufficient elasticity to allow every part of the raised device on the block to acquire a coating of color. The calico beino- laid flat on a table covered with a blanket, the charged block is applied to its surface (the printer being guided where to apply the black by small pins at the cor- ners) and struck gently to transfer the impression. The application of the block to the woollen cloth and the calico alternately is continued until the whole piece of calico is printed. By the ordinary method, a single block prints only a single color; hence, if the design contain five or more colors, and all be printed by block, five or more blocks will be required, all equal in size with the raised parts in each corresponding with the depressed parts in all the others If the design, however, requires different colors to be applied in fio-ures in straight and parallel stripes, all the stripes may be applied by one block at a