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Methods of Printing

block, colour, blocks, table, sieve, cloth, surface and cut

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METHODS OF PRINTING Hand Blocks.—These are made of box, lime, holly, sycamore, plane or pear wood, but generally one of the last three. The blocks vary in area, but are always two or three inches thick and are backed with pieces of deal or pine, the grain of each adjacent piece running in a different direction. All are secured firmly to gether to prevent warping. When the surface of the block has been planed and rubbed level, the outline of the design is put on by applying a tracing in lamp black and oil to the surface and rubbing. The portions to be left in are tinted with ammoniacal carmine or magenta, the block is damped and the parts which are not required are cut away, commencing with the heavier masses and proceeding to the finer ones. The latter are some times cut on a separate block. Coppered blocks are used for fine work and these are made by inserting strips and pegs of brass or copper into the surface of the block. Burch of Accrington de vised an instrument (fig. I) for preparing blocks which closely resembles a drilling machine used by engineers, but in place of the drills, fixed punches (heated by a small gas blow-pipe or bunsen burner) can be raised or lowered by a foot lever, while the block is moved about by the worker. The heated punches are sometimes made to revolve. Blocks are often felted or flocked so that more colour can be applied to the cloth, and this secures better penetration.

In addition to the engraved block, a stone printing table and a colour sieve are required. Over the table top a woollen printer's blanket is tightly stretched. At one end, the table is provided with a couple of iron brackets to carry the roll of cloth, and, at the other, a series of guide rollers, extending to the ceiling, are ar ranged for the purpose of sus pending and drying the newly printed goods. The colour sieve consists of a swimming tub, half filled with starch paste on the surface of which floats a frame, covered at the bottom with a tightly stretched piece of mack intosh or oiled calico. On this the colour sieve proper, a frame cov ered with fine woollen cloth, is placed, and forms, when in posi tion, an elastic colour trough over the bottom of which the colour is spread evenly with a brush.

The modus operandi of print ing is as follows : The printer commences by drawing a length of cloth, from the roll, over the table, and marks it to indicate where the first impression of the block is to be applied. He then applies his block in two different

directions to the colour on the sieve and finally presses it firmly and steadily on the cloth, ensuring a good impression by striking it smartly on the back with a wooden mallet. The succeeding impressions are made in the same way, continuity being ensured time to time, but of these only two—"tobying" and "rainbowing" —are of any practical value. The object of "toby-printing" is to print the several colours of a multicolour pattern at one opera tion, and a block, with the whole of the pattern cut upon it, and a specially constructed colour sieve are employed. The latter consists of a thick block of wood, on one side of which a series of compartments are hollowed out, corresponding roughly in shape, size and position to the various objects cut on the block, and supplied with colour to correspond to the design.

The Perrotine.

Three blocks (3 ft. by 3 ft.-5 in.), with the pattern cast on them in relief, are brought to bear successively on the three faces of a specially constructed printing table over which the cloth passes (together with its backing of printer's blanket) after each impression. The faces of the table are arranged at right angles to each other, and the blocks work in slides similarly placed, so that their engraved faces are per fectly parallel to the tables. Each block is provided with its own colour trough, distributing brush and woollen colour pad or sieve, and is supplied automatically with colour by these appliances during the time the machine is in motion. For certain classes of work the perrotine possesses great advantages over the hand block, for not only is the rate of production greatly increased, but the joining up of the various impressions to each other is much more exact, and no sign of a break in continuity of line is . noticeable in well executed work. However, the perrotine can only be used for patterns containing not more than three colours and not exceeding 5 in. in vertical repeat, whereas hand block printing can cope with patterns of almost any scale and contain ing any number of colours. The two processes, therefore, cannot be compared on the same basis ; the perrotine is best for work of a utilitarian character and the handblock for decorative work in which the design only repeats every 15 to 20 in. and contains colours varying in number from one to a dozen.

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