The cylinder-machine consists of a hollow cylinder of copper about three feet long and three or four inches in diameter, whose sur face is engraved, not by the hand-graver, but by the mechanical pressure of a steel roller from one to two inches in diameter, and three inches long, which transfers the figures engraved on it to the relatively softer copper. The first steel roller, called the die, is softened before being engraved in intaglio ; it is then hardened, and made, by a powerful press, to transfer its design in relief to a similar die called the mill, which is the one used for transferring the design to the copper cylinder. The process of etching is also sometimes had recourse to for covering the cylinder with various figures.
The engraved cylinders are mounted upon a strong iron shaft or arbor, carrying a toothed wheel at its end, in order to put it in train with the rotatory printing machine, for one, two, or more colours. On a roller, at the upper part of this apparatus, are wound whole calico webs stitched together, the end of which is then introduced between the engraved copper cylinder and a large central cylinder covered with blanket, against which it is made to bear with regulated pressure. The en graved cylinder turns on the top of another cylinder covered with woollen cloth, which revolves with the former while its under part is plunged in an oblong trough containing the dyeing matter, which is of a pasty consistence. The engraved cylinder is thus supplied with an abundance of impressible colour, and is cleared from the superfluity by the thin edge of a flat ruler made of bronze, called vulgarly the doctor, which is applied obliquely to it with a gentle force. The cylinder, after its escape from this wiping tool, acts upon the calico, and rolls it onwards with its revolution, imparting its figured design with great preci sion. One single machine will print calico at the rate of a mile an hour.
Dye-stuffs, capable alone of imparting fast colours to calico, have been called substantive; and such as require the intervention of a mordant, adjective. Indigo, catechu, and certain metallic oxides belong to the former class ; madder, cochineal, and Persian berries to the latter. There are five general styles of work in calico printing The fast colour or chintz style, in which the mordants are applied to the white cloth, and the colours of the design are afterwards brought up in the dye-bath. 2, Where the whole surface re ceives a uniform tint from one colouring mat ter, and figures of other colours are -afterwards brought up by chemical discharges and reac tions ; this is called the Itongeant style in France. 3, Where the white surface is impressed with figures in a resist-paste, and is afterwards subjected to a general dye, such as the indigo-vat. 4, Steam-colours, in which a mixture of the mordants and dye-extracts is applied to the cloth, and the chemical com bination is effected by the agency of steam. 5, Spirit-colours, consisting of mixtures of dye-extracts with nitro-muriate of tin; these cannot be exposed to a steam heat without corroding the cloth : this style is brilliant, but fugitive.
The tint or shade of colour produced in the dyeing-bath is proportional to the strength of the mordant previously applied to the cloth. The thickening of mordants is one of the most important operations in calico-printing ; for the permanence and beauty of the impres sion depend not a little on the consistence and quality of the inspissating substance.
The substances usually employed in thicken ing are flour starch ; flour ; roasted starch ; gum Senegal ; gum tragacansh ; salep ; pige• clay mixed with gum Senegal ; potato starch; sulphate of lead and gum ; sugar ; treacle; glue.
In the printing of yellows, greens, purples, pinks, and browns, different colouring sub stances are used, and different processes adopted for causing the colours to combine permanently with the cloth ; but they all pos • sess a common character, inasmuch as mordants are applied to the white cloth, and the colours of the design are afterwards brought up in the dye-bath.
In almost all the modes of calico-printing, the processes are very numerous, to ensure the beauty and the permanence of the colours. In what is called the steam-colour printing, the agency of steam is applied to aid in fixing the colours to the cloth. The cloth is first steeped in a mordant liquor ; then printed by the cylinder with various colours, which for their peculiar properties are called steam colours. The cloth is hung np to dry, and when dry it is exposed to the action of dry steam. This is done by five different kinds of apparatus—the column, the lantern, the cask, the steam-chest, and the chamber. The first of these, which is most frequently used, is a hollow copper cylinder about 45 inches long by 2 to 6 in diameter, perforated along its whole surface with small holes one quarter of an inch apart. To the lower end of the column a circular plate is soldered, which serves to prevent the cloth coiled round the cylinder from falling down from it. The bottom of the hollow cylinder is terminated by a tube one inch wide, which fits tight into the socket of an iron chest beneath it, into whose side the steam pipe of supply enters. The goods printed with the steam-colours and properly dried are lapped tight round this hollow cylinder, and covered exteriorly with an envelope of strong cotton cloth, blanket stuff, or flannel. The steam is then let on, and continued for 20 or 30 minutes, according to the nature of the dyes. The steam being stopped, the printed goods are rapidly un rolled from the column while still hot, lest any condensation of vapour should take place to stain them.
A pretty and ingenious method of producing the `rainbow' pattern is as follows : a num ber of sieves, containing the different shades of colour, arc placed nearly under each other, over each sieve a disc revolves, having pro jections of copper wire, which dip into the colours. These discs are supported on pe destals which admit of easy adjustment, and are so regulated, that as they revolve the projecting wires give colour to the cylinder in successively lighter shades.
The designs for calico printing are very costly. A copper cylinder is worth from 51. to 71. ; and the engraving costs from 51. to 101. more. A constant succession of new patterns must be kept up by the manufacturer to pro duce novelties ' for the season. Some of the Lancashire firms expend as much as 50001. a year in designing and engraving new patterns. Property in these designs is secured by law. [DESIGNS, COPYRIGHT, AND REGISTRATION.] The art of designing now receives encourage ment from the government. [DESIGN, SciirooLs or.] In the year ending June 1846, the printed and dyed cotton goods exported from this country amounted to 32,7,165,580 yards.