688. Papers for Transfer Printing. Transfer may be made on nearly all papers, but it is easier to get good results on the unsized or half sized papers generally used in printing artists' proofs in copper-plate, in particular Holland, Arches, and Japanese papers. Choose papers of cream or light chamois tint for printing in black ; white papers for printing with coloured inks.
For press transfers, the unsized or half-sized papers should be damped. Sized papers are generally used dry, with the exception of drawing papers, which are slightly moistened.
For " without press " transfers of prints of about io x 8 in., the paper does not usually need to be moistened.
Printing on damp paper always slightly reduces the contrasts in the picture.
In case of urgency the sheet to be moistened is dipped in water, drained, and wiped between two smooth blotting boards, preferably by passing through the press. When a certain number of prints are to be made, the method adopted by printers is followed : a piece of zinc or glass larger than the paper is placed flat on a table ; on it are placed in succession a dry sheet, a sheet wetted by immersion in a dish of water, two dry sheets, a moist sheet, and so on, finishing with a dry sheet. The pile is covered with a piece of zinc or glass, and a weight is placed on top. In a few hours moisture spreads uniformly throughout the pile, and for several days the sheets will retain the suppleness desired.
\Vetting with water can be replaced by im pregnation with liquids which give the paper a greater affinity for the fatty ink which can then be transferred with less pressure, i.e. without crushing the grain of the paper. Good results have been obtained with petrol (R. Demachy, 689. Press Transfer. For the transfer a lithographic press may be used, scraper or cylinder type, or a copper-plate press.' When a press is specially procured, the most suitable are small models of copper-plate presses used by engravers for taking proofs. On the bed of the press, in steel, or, more frequently, in wood covered with zinc, one or two thicknesses of woollen blanket are laid of the same size as the bed. After unscrewing the tightening screw and lifting the upper cylinder by means of blocks slipped under the cylinder bearings, the bed is placed between the cylinders, taking care that its long sides are perpendicular to the common direction of the axes of the cylinders. The upper cylinder is allowed to fall back on the blanket pad, the two screws are tightened equally, and the hand-wheel is turned to engage under the cylinders at most a quarter of the length of the bed. Raising the blankets, there is then placed
on the bed the following : (I) a piece of blotting board at least in. larger than the printing paper; (2) the inked print, face uppermost, centring it correctly on the blotting-board (the edges of the print should have been cleaned, if necessary, with a wad of clamp cotton-wool) ; (3) the printing paper, face downwards, cor rectly centred on the blotting-board ; (4) a second blotter of the same size as the first. On this blotter the blankets are pressed down, one by one, smoothing them at the same time. The handwheel is turned, slowly but continuously, 2 till the sheets of paper are completely conveyed to the other side of the cylinder. The blankets are then lifted and the papers successively withdrawn.
69o. Transfer Without Press. The transfer of the image on to its final support may be done without a press, by using, for the necessary pressure, the back of a spoon or a large modelling boxwood chisel. It is then necessary to go over every part of the image several times, crossing the paths of the tool used, frequently ascertain ing the result by partially lifting the printing paper and replacing it in exactly the same position on the inked print. Not only is this work tedious for a sheet of large size, but there is a risk of the paper not falling back exactly into its original place, thus giving rise to a double image.
The work is made easier by using a drawing board and placing towards one of its ends two pins fitted with wing nuts, by means of which a perfectly straight bar of wood, covered with thick felt on its under side, may be clamped on the inked print. Between the pins is slipped a zinc sheet as support, on which is placed, as in the case of transfer with a press, the inked print (the edges of which may be covered with strips of parchment paper) and the printing paper, which is covered, if required, with a protecting sheet of stiff paper. The latter is for avoiding marks of the chisel on the printing paper. The whole is screwed down under the bar of wood, leaving the essential part of the image free, so that it is possible from time to time to raise the printing paper in order to judge of the progress of the transfer and to note the parts needing accentuation.
We may add that many artists use the chisel, after press transfer but before separation of the various layers, for the purpose of increasing the vigour of blacks by transferring all or part of the ink remaining attached to the print after passage through the press.