TOPICAL DYEING or CALICO ruiNTING, is the art of printing various coloured patterns upon plain calicoes by applying certain colourless morclaunts to the cloth.
This beautiful art is one of great antiquity, and was carried to considerable perfection in India. As the object in this brief sketch is not to instruct the calico printer, but to give the general reader an idea of this singular art, we shall omit all the previous processes of preparing the calico for the printer.
The pattern to be impressed on the calico was formerly cut out in relief on a wooden block of the requisite size, exactly like a wooden cut for figures or diagrams. The wood used was generally holly, and the cutting of the pattern formed a separate trade called block-cutting. The perishable nature of wood, however, involved the printer often in much expense, and hence a great improvement has taken place by using slender pieces of brass or copper, which are fixed on the wood so as to produce the pattern, and which give greater sharpness and pre cision to the impressions. The next implement is the sieve with its case. The sieve consists of a broad boo? like that of a tambourin with a piece of superfine woollen cloth stretched tightly across it. The case consists of another wider hoop covered with sheep skin or oil cloth. The sieve placed in its case is now plunged in a tub of gum water.
The mordaunt mixed up with paste made of flour or a thick solution of gum Arabic, or gum Senegal, or gum nigacanth, is then spread with a brush on the cloth of the sieve, a part of the process which is called tecsing. When the mordaunt is colourless, as the acetate of alumine, a little purple dye with a decoction of Brazil wood is mixed up with it to sfghten it as the workmen say, or to make the pat tern apparent to the eye.
The workman now takes the pattern block in one hand and the sieve in the other, and applying the surface of the block to that of the sieve, he then takes up a sufficient quantity of the thickened mor daunt so as to cover every part of the surface of the pattern formed by the copper lines. He then applies
the block to the calico and impresses it with a gen tle blow from a mallet. In this manner he goes over the whole piece. When a variety of colours is required, several different mordaunts are requi red, as different colours require different mordaunts to fix them. In order to evaporate the acids of the mordaunts, which might weaken the fabric of the cloth, the calico is placed in a room called the stove; heated with flues to about 90°. When the common red liquor mordaunt is used, the calico re mains here about 24 hours; but when citric acid is used, a much shorter time is nesessary, and when a strong muriate of lime has been employed, half an hour of the stove is sufficient.
When iron liquor is the mordaunt, the intensity of the colour is increased, and the process much improved by exposing the calico for several days to the atmosphere. The black oxide of iron then ac quires an additional dose of oxygen, and approaches nearer to the red or peroxide, which is the pre ferable mordaunt. Mr. Parker suggests it as an ob ject of inquiry, whether or not the substitution of a current of atmospheric air for a great part of the drying in the stove, might not be an advantage.
The calico is now washed with water and a little cow dung, at various temperatures, an operation of from 5 to 40 minutes, which revives the uncom bined part of the mordaunt, and which is now per formed in what is called dunging machines. Mr. Parker is of opinion, that the dung. (which Bethol let found to contain a substance like bile,) imparts an animal matter to the fibres of the calico, which acts as an additional mordaunt.
When the goods are perfectly rinsed in river and tepid water, they are boiled for ten or fifteen min utes in madder, and in the process called maddering, the calicoes receive, at one operation, all their re quisite colours. The colouring matter of the mad der is precipitated to a red by one mordaunt, to a purple by another, and to a black by a third, so that we can obtain every possible shade, from a lilac to a black, or from a pink to a red.