The coated side of the paper appears yellowish. It is then printed as usual until the deepest parts look grey, as the prints look weaker after developing. The prints are developed by floating them face downwards on a dish of pure water not too cold, and then washed till the drawing appears quite white on a blue ground. The washing must be thoroughly done or else the prints turn blue afterwards when exposed to light. These prints contain all the finest details, even in the deepest shadows, plainly visible, and will now be the most, perfect and most convenient proofs for the artist. The tracing or drawing is now done with good black dull surface ink as already suggested. When the drawing is done it is allowed to dry thoroughly, which will be in from two to three hours. The following solution should be prepared:—
| Oxalic acid | 1 | part |
| Water | 10 | part |
which should be poured into a flat dish and the drawing allowed to lie in it for about thirty minutes. It is then again well washed and then immersed for fifteen minutes in a bath of
| Hydrochloric acid | 1 | part |
| Water | 20 | part |
The blue colour will now have disappeared, and the ink drawing will appear pure black on the white paper. It should be now hung up and dried in the ordinary way. This drawing prepared in wash or line with ink now forms the original for a further photographic negative, which is made in the correct size of the reproduction with or without the intervention of the crossed screen according to the character of the drawing. With the negative thus obtained a photo-litho on stone or zinc, or a typographic copper or collotype plate, or a photograph on wood for xylography may be prepared.
The use of this process appears specially important for those cases in which an ordinary photographic negative is not sufficient, {25} for example where a printing plate cannot be prepared from the negative. It ought also to be useful when the light could not be controlled in making the negative, and thus incorrect effects appear in the reproduction, which often occurs in negatives from nature and with polished plastic metal objects. The enlargements from the original are then used because the details can be better seen, and the artistic character can be more easily seen. The fineness of the drawing must obviously be in proportion to the after reproduction, while tones may be partly or entirely lost.
(C.) DRAWINGS ON PREPARED PAPERS.
For photo-litho transfer without the use of a screen there are some commercial papers, toned, grain, net or pyramid grained papers which may be used with excellent results.
On these papers, according to their preparation, various excellent results can be obtained, which possess high claims as illustrations.
A smooth white scraper board made by Angerer and Göschl of Vienna, which has a very even film of chalk, and which takes the lines clean and vigorously, is especially suitable for pen and ink work. On this paper plucky drawings like woodcuts can be executed. The perfect whites of the paper, combined with the vigorous beautiful black, facilitate reproduction with excellent results and without much trouble.