Face of Block for Calico Printing. Back of Calico Block.
The printing block, which is worked by hand, is charged with colour by pressing it gently upon a piece of superfine woollen cloth called the sieve, stretched tightly over a wooden drum, which floats in a tub full of size or thick varnish to give it elasticity, so that every part of the raised device may acquire a sufficient coating of colour. The sieve is kept uniformly covered with the colouring matter by a boy or girl called the tearer, who takes up with a brush a small quantity of the colour contained in a small pot, and distributes it uniformly over the surface; for if this were not done, the block would take up the colour unequally.
The printing shop is a long well-lighted apartment, the air of which is kept warm for the purpose of drying the cloth as it is printed; to insure which it is passed over hanging rollers, so as to expose a large surface to the air. The printing table, which is about six feet long, is made of some well seasoned hard wood, such as mahogany, or of marble, or flag-stone, the object being to present a perfectly flat hard surface. This table is covered with a blanket, upon which the calico is extended, and the block, being charged with colour, is applied to its surface, a blow being given with a wooden mallet to transfer the impression fully to the cloth. It is necessary, of course, to join the different parts of the design with precision, and in doing so the printer is guided by small pins at the corners of the block. Thus, by repeated applications of the block to the woollen cloth and to the calico alternately, the whole length of calico is printed.
Drying Room.
By this method, a single block prints only one colour, so that, if the design contain three or more colours, three or more blocks will be required, all of equal size, the raised parts in each corresponding with the depressed parts in all the others; in order, therefore, to print a piece of cloth twenty-eight yards long, and thirty inches broad, with three blocks, each measuring nine inches by five, no less than 672 applications of each, or 2,016 applications of the three blocks, are necessary. Thus it will be seen that printing by hand is a tedious operation, requiring more diligence than skill.
Brush.
When the design, however, consists of straight parallel stripes of different colours, they may be applied by one block at a single impression. For this purpose the colours are contained in as many small tin troughs as there are colours to be printed. These troughs are arranged in a line, and a small portion of each colour is transferred from them to the woollen cloth by a kind of wire-brush. The colour is distributed evenly in stripes over the surface of the sieve by a wooden roller covered with woollen cloth. For the rainbow style, as a peculiar pattern is called, the colours are blended into one another at their edges by a brush or rubber.
An important improvement has been made in the construction of hand-blocks, by the application of a stereotype plate as the printing surface. A small mould is produced from a model of the pattern, and the stereotype copies are then made by pouring mixed metal into it. A number of the stereotype plates are then formed into a printing block, by being arranged in a stout piece of wood.