Tuesday, July 31, 2012

Block Printing on Textiles: Part II

      Woodblocks for textile printing may be made of box, lime, holly, sycamore, plane or pear wood, the latter three being most generally employed. They vary in size considerably, but must always be between two and three inches thick, otherwise they are liable to warping, which is additionally guarded against by backing the wood chosen with two or more pieces of cheaper wood, such as deal or pine. The several pieces or blocks are tongued and grooved to fit each other, and are then securely glued together, under pressure, into one solid block with the grain of each alternate piece running in a different direction.
      The block, being planed quite smooth and perfectly flat, next has the design drawn upon, or transferred to it. This latter is effected by rubbing off, upon its flat surface, a tracing in lampblack and oil, of the outlines of the masses of the design. The portions to be left in relief are then tinted, between their outlines, an ammoniacal carmine or magenta, for the purpose of distinguishing them from those portions that have to be cut away. As a separate block is required for each distinct colour in the design, a separate tracing must be made of each and transferred (or put on as it a termed) to its own special block.
      Having thus received a tracing of the pattern the block is thoroughly damped and kept in this condition by being covered with wet cloths during the whole process of cutting. The blockcutter commences by carving out the wood around the heavier masses first, leaving the finer and more delicate work until the last so as to avoid any risk of injuring it during the cutting of the coarser parts. When large masses of color occur in a pattern, the corresponding parts on the block are usually cut in outline, the object being filled in between the outlines with felt, which not only absorbs the colour better, but gives a much more even impression than it is possible to obtain with a large surface of wood. When finished, the block presents the appearance of flat relief carving, the design standing out like letterpress type.
      Fine details are very difficult to cut in wood, and, even when successfully cut, wear down very rapidly or break off in printing. They are therefore almost invariably built up in strips of brass or copper, bent to shape and driven edgewise into the flat surface of the block. This method is known as coppering, and by its means many delicate little forms, such as stars, rosettes and fine spots can be printed, which would otherwise be quite impossible to produce by hand or machine block printing.
      Frequently, too, the process of coppering is used for the purpose of making a mold, from which an entire block can be made and duplicated as often as desired, by casting. In this case the metal strips are driven to a predetermined depth into the face of a piece of lime-wood cut across the grain, and, when the whole design is completed in this way, the block is placed, metal face downwards in a tray of molten type-metal or solder, which transmits sufficient heat to the inserted portions of the strips of copper to enable them to carbonize the wood immediately in contact with them and, at the same time, firmly attaches itself to the outstanding portions. When cold a slight tap with a hammer on the back of the limewood block easily detaches the cake of the type-metal or alloy and along with it, of course, the strips of copper to which it is firmly soldered, leaving a matrix, or mold, in wood of the original design. The casting is made in an alloy of low melting-point, anti, after cooling, is filed or ground until all its projections are of the same height and perfectly smooth, after which it is screwed on to a wooden support and is ready for printing. Similar molds are also made by burning out the lines of the pattern with a red-hot steel punch, capable of being raised or lowered at will, and under which the block is moved about by hand along the lines of the pattern.
Woman doing Block Printing
at Halasur village, Karnataka,
      In addition to the engraved block, a printing table and color sieve are required. The table consists of a stout framework of wood or iron supporting a thick slab of stone varying in size according to the width of cloth to be printed. Over the stone table top a thick piece of woolen printers blanket is tightly stretched to supply the elasticity necessary to give the block every chance of making a good impression on the cloth. At one end, the table is provided with a couple of iron brackets to carry the roll of cloth to be printed and, at the other, a series of guide rollers, extending to the ceiling, are arranged for the purpose of suspending and drying the newly printed goods. The color sieve consists of a tub (known as the 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 mackintosh or oiled calico. On this the color sieve proper, a frame similar to, the last but covered with fine woolen cloth, is placed, and forms when in position a sort of elastic color trough over the bottom of which the colour is spread evenly with a brush.
      The printer commences by drawing a length of cloth, from the roll, over the table, and marks it with a piece of colored chalk and a ruler to indicate where the first impression of the block is to be applied.
      He then applies his block in two different directions to the color 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 second impression is made in the same way, the printer taking care to see that it fits exactly to the first, a point which he can make sure of by means of the pins with which the blocks are provided at each corner and which are arranged in such a way that when those at the right side or at the top of the block fall upon those at the left side or the bottom of the previous impression the two printings join up exactly and continue the pattern without a break. Each succeeding impression is made in precisely the same manner until the length of cloth on the table is fully printed. When this is done it is wound over the drying rollers, thus bringing forward a fresh length to be treated similarly.
If the pattern contains several colours the cloth is usually first printed throughout with one, then dried, re-wound and printed with the second, the same operations being repeated until all the colors are printed.
Textile fragment, 24 cm x 21 cm, made
circa 1545 - 1645 AD. Produced in
India for export,found in Fustat,
 Egypt. The brown colored pattern
 is formed by the use of a mordant
 applied to theground cloth with a single
 stamp. The red dye was then painted
 on. The outline of the square block,
 forming four quarter circles
 with the star shape in the middle,
 is faintly visible.
      Many modifications of block printing have been tried from time to time, but of these only two tobying and rainbowing are of any practical value. The object of tobey printing is to print the several colors of a multicolor pattern at one operation and for this purpose a block with the whole of the pattern cut upon it, and a specially constructed color sieve are employed. The sieve 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. The tops of the dividing walls of these compartments are then coated with melted pitch, and a piece of fine woolen cloth is stretched over the whole and pressed well down on the pitch so as to adhere firmly to the top of each wall; finally a piece of string soaked in pitch is cemented over the woolen cloth along the lines of the dividing walls, and after boring a hole through the bottom of each compartment the sieve is ready for use. In operation each compartment is filled with its special color through a pipe connecting it with a colour box situated at the side of the sieve and a little above it, so as to exert just sufficient pressure on the colour to force it gently through the woolen cloth, but not enough to cause it to overflow its proper limits, formed by the pitch-soaked string boundary lines.
      The block is then carefully pressed on the sieve, and, as the different parts of its pattern fall on different parts of the sieve, each takes up a certain color that it transfers to the cloth in the usual way. By this method of tobying from two to six colors may be printed at one operation, but it is obvious that it is only applicable to patterns where the different colored objects are placed at some small distance apart, and that, therefore, it is of but limited application.

No comments:

Post a Comment