To secure an accurate fit, or "register," as it is termed, the outline-block is usually finished first, and the pattern is printed from it in lithographer's ink upon a smooth surface of floor cloth. While this ink is still wet, a fresh block is laid upon it, pressure is applied by means of an ordinary screw-press, and the pattern will be found transferred to the surface of the pear wood. This process is repeated with other blocks, as many times as there are colours in the pattern. To keep the blocks in good condition, it is essential that they should be cleaned before the paint has time to harden upon them. This cleaning is best effected by washing them in coal-tar naphtha, with the aid of stiff scrubbing-brushes. Naphtha containing petroleum-spirit should be avoided for this purpose. as its solvent power is much less. Spirit of turpentine is sometimes used ; this is both more expensive, and more injurious to the workmen, who are constantly exposed to its vapour. Once the paint has been allowed to dry upon the blocks, they can only be cleaned by the slow process of scraping each separate little piece of wood or metal. They should be kept in a dry room, protected from sudden changes of temperature. If exposed to damp, they are liable to warp, and become useless for printing on fiat surfaces. In hand printing the printer stands between two tables, one covered with as many pads as there are colours in the pattern to be printed, and another supporting the floorcloth during the operation. The pad-table is generally furnished with a shelf for the paint-pots. The width of the printing-table slightly exceeds that of the blocks ; its length depends upon the width of the fabric to be printed upon it. Figs. 715 and 716 give a section, and front view of part of a table for hand printing. The surface is padded with several thick nesses of flannel, or one of felt, and is then covered with a piece of oilcloth or thin flooreloth. At the sides, are hand-punches and pins 1, by which is regulated the length of fabric pushed forward each time. There are two methods of ensuring accuracy in the "register" of the impressions. One is by driving pins into the corner of the face of each block; these, being in a prominent position, can be seen by the printer as he lowers the block, and as the pins of the first block leave small dots of paint upon the printed surface, it is easy to adjust the following ones. Should the small dots not be covered by the outline-block, they are removed by a palette knife while still wet. Another and preferable method is to fix, across that side of the table next to the printer, a ,-shaped bar of steel or iron n. Upon the upright edge of this bar, 11-shaped stops are adjusted by screws, at intervals corresponding with the width of the blocks. One side of each block is furnished with two projecting metallic pegs, and if the printer brings these pegs into contact with the fixed stops before lowering the block, an accurate register is ensured. Along the whole length of the table, and higher than the head of the printer, run two strong beams q, between which hangs the press. This is suspended so that it rests upon small rollers, which run on iron rails screwed to the upper surface of the beams. The frame of the press is furnished with cross-pieces, which catch the beams as soon as pressure is applied, and prevent the press from rising. The press itself is a simple screw press, with a single short lever p'. The pitch of the screw is so adjusted that about turn of the handle suffices to exert the whole pressure. A spring is inserted to cause the bottom of the press to rise instantly when the handle is released. That part of the press which touches the blocks turns on a swivel, and has two pro jections on its lower aide, each of which falls on one side of the block ; the pressure is thus equalized. A short leather strap is nailed to the back of each block, forming a loop, under which the printer passes his hand, for the purpose of lifting the block.
The pads are covered in the same way as the printing table. The colour is spread over them by means of paint brushes, and, in order to save the printer's time, this part of the work is generally performed by boys. It
may here be remarked that, on account of the largo proportion of lead contained in most of the paints, the greatest cleanli ness is necessary in this department ; the hands and face especially should not be brought into contact with the pigments, and beginners should be warned as to the possible results of carelessness. In distributing the colour over the face of the pad, care must be taken to ensure uniformity, as the slightest inequality would show on the printed surface. The block must be laid perpendicularly upon both the colour-pad and the fabric to be printed, as the least lateral movement would suffice to destroy the accuracy of the impression. Where any error in the printing has occurred, the paint is removed by a palette knife while still wet, the surface of the floorcloth is cleaned with naphtha or spirit of turpentine, and a piece of tow, and a fresh impression is made. The paint as used has about the consistence of treacle, and, if kept for any length of time, it should be covered with water, which prevents the formation of a skin over the surface. The oil used for mixing the paint is composed of equal parts of boiled and raw linseed oil. Both these should be allowed to settle in tanks for at least a month before use. The proportion of driers to be added to the paint de pends to a great extent upon the nature of the pigment. For ordinary dark paints, ground lith arge is used; for white and the mote delicate tints, acetate of lead (sugar of lead) is neces sary. Although a large proportion of driers hastens the solidification of the oil which forms the medium of the paint, yet the film produced is not so elastic or so durable as when a smaller quantity is used. Raw oil alone gives a much better film than boiled oil; but an addition of the latter is necessary to meet the practical requirements of the case, raw oil drying too slowly.
Before pouring water on the surface of the mixed paint, the brushes should he removed, and immersed in oil, to keep them from drying, as water softens the glue with which the bristles are fastened, and loose hairs may then be trans ferred to the blocks.
Although paint brushes are still usually employed for distributing the colour on the pads, yet a species of " doctor " or scraper has recently been introduced, which threatens to supplant them entirely for this purpose. Its construction is shown in Figs. 717 to 719 : a is a bottomless trough, slightly shorter than the colour-pad upon which it stands, but longer than the block to be supplied with paint ; it is constructed of sheet iron or steel, and one edge d is serrated, or rather furnished with teeth like a comb. The paint is poured into the trough as it rests upon the pad, and would run out through the spaces between the teeth, were it not prevented by the outer plate b. This plate, the lower edge of which is rounded off to prevent injury to the surface of the pad, can be so adjusted as to regulate the quantity of paint passing beneath it. The bolts c are furnished with eccentrics, which act upon one of the plates only, so that by turning them, the outer plate or " doctor " is raised or lowered at pleasure. In using, this trough, no paint-brush of any kind is needed. The paint can he kept in a can, and poured out as required, and the pads are cleaned with a palette knife after nee. The only alteration required in the pads is a narrow ledge about in. high on the upper side, to prevent the paint running off.
Machine Printing.—Many attempts have been made to print flooreloth by machinery ; but their success has, with one exception, been only partial. All cylinder-machines are prednded, because, in order to ensure durability, the paint must be laid on thickly, and while the cylinder is re volving part of the paint runs downwards on its face, rendering one part of the impression thicker than another. Even machines which closely imitate the movements of hand printing have defects e. g. they cannot be worked at a high speed, the paint being liable to splash when the blocks are raised too quickly. For simple patterns, the following machine has been found to work well in practice. Figs. 720 and 721 are side views, and Fig. 722 is a transverse section of it.