CALICO-PRINTING.
CALICO-PRINTING WORKS.
FIG. 1.
AGEING PROCESS.
Calico-printing is executed either by hand (with wooden blocks having the pattern engraved—projecting—on their surfaces) or by means of machinery. Printing by hand-blocks is a tedious operation, and is now almost superseded by the cylinder. The hand process is very similar to that made use of in paper-staining (which [see]). Cylinder-printing is a much more rapid process, conducted by means of a brass cylinder with the pattern engraved on its surface, which is made to revolve against another cylinder covered with flannel, and charged with color from a trough into which its lower part is dipped. The calico is passed over a large cylinder made to revolve in contact with that on which the pattern is engraved, and which is charged with color from the one below it. [Fig. 1] shows this arrangement, a being the large cylinder with the calico round it, b the engraved cylinder, c the color cylinder, and d the color trough. As the engraved cylinder revolves, it prints the pattern at each revolution, and this is repeated again and again, to the whole length of the piece of calico. In some machines there are several engraved cylinders, each printing its own color, and so arranged that the colors shall fit into the parts of the design requiring them, the whole making up the complete pattern.
DRYING ROOM.
Before being printed, the calico is prepared by being passed through a preparation, called a mordant, capable of fixing the colors, and preventing them being washed out, and several of these are used, according to the colors required. The colors are thickened with paste, so as to prevent them from running into each other when printed. Muslins, chintzes, &c., are printed in a similar manner to calicoes.
When the pieces of calico come from the printing cylinders, they are made to pass upwards through holes in the ceiling to a room above, where they pass over surfaces of iron heated by steam, so as to thoroughly dry them; they then descend through the floor into the printing room, where they are packed. The process called “ageing” consists in exposing the calicoes to the air for a certain time, to take off the harshness and stiffness peculiar to new goods.
In some cases the colors themselves are not printed on the goods, the mordants being used instead, and the whole piece is then boiled in a vat of dye-stuff, which, however, only adheres to the parts printed with the mordant, all the rest being easily got rid of by simple washing.