The paper should be squeegeed on to plate-glass, as already described, and allowed to dry spontaneously. The paper when stripped from the plate-glass shows a beautiful high glaze, and can be kept fit for use for twenty-four hours. When the paper is older it can still be used, but the development is more difficult, and it is better to avoid this for fine drawings or autotypes.
Albert does not recommend a photometer to be used when printing this paper, but by examination of the print to judge when this is correct. The image should have a brown tone, and be easily distinguished by the eye from the ground. Over-printing is disadvantageous, as the lines and points become broader, the prints develop badly, the tint adheres firmly to the ground, and the details in the deepest shadows are lost.
The inking and developing can be done by any of the known processes which is thought desirable. The chief thing is that too much ink must not be used in the first inking up; any intensification required may be effected with a second coating. This is, especially for fine drawings and autotypes, very important, whilst for coarser work also once inking is sufficient. The prints are then placed in cold water, and after sufficient washing should be developed with a soft pad or pad of wool, with which any tint can be very easily removed from any parts which should remain white.
3. THE PHOTO-LITHOGRAPHIC TRANSFER.
(A.) TREATMENT OF THE PHOTO-LITHOGRAPHIC PRINT AND THE PLATE.
The transfer from the bichromated gelatine paper requires generally, as regards treatment and choice of the material, greater care on the part of the printer than an ordinary transfer, and this increases in transferring fine drawings or autotypes on to stone.
In the first place the good quality of the stone should be looked to. For ordinary or coarsely drawn subjects this is of less importance, but for fine drawings and autotypes it is of the highest importance. Further, accuracy and cleanliness are all important, without which successful work is impossible. On the other hand, a transfer can hardly fail if it be accurately and correctly performed.
When the print comes from the developing bath, and has been well washed so that every trace of bichromate is removed, it should be freed from excess of water between blotting-paper. It should then be dried in a not too warm place free from dust till the gelatine has completely set and feels absolutely dry. The relief will have now again disappeared, and the black and white places lie in the same plane. It is best dried by pinning it to a board with drawing pins, and then set up in a dry place.
In the meanwhile the transfer stone should be prepared, which must be absolutely faultless. Just before the transfer it should be dry polished with pumice stone, and then well dusted with a {58} cloth. The slightest grain will give a spot in a fine tone. Obviously the stone must be well ground so that neither any spots nor lines of an earlier transfer can appear. With an open drawing this can be corrected, but not with an autotype; in such a case the shortest way is to make a new print and a new transfer.
The print is first wiped over on the back with a damp cloth, and then laid on damp blotting-paper. After about five minutes the print is treated a second time with a damp cloth, and then laid between damp blotting-paper. It is not advisable to lay the print between ordinary damp blotting-paper, as the gelatine becomes somewhat sticky, and would attract particles from the rough paper.