Factitious Negatives may be produced by coating a plate with a transparent but non-actinic coating, and by removing or erasing in a suitable manner designs may be copied without the use of a camera or lens. Professor Husnik and others have published different methods whereby the artist is enabled to transfer the creations of his pencil to zinc or stone, without resorting to the aid of the photographic negative process, although the subsequent operations may still entitle it to be styled photo-lithography.
The process most likely to lead to success consists of first coating a glass plate with a strongly iodised collodion, sensitising as usual, well washing on both sides and drying. To engrave, lay the plate upon a black cloth, and the design may be traced and engraved upon the surface by means of etching points or needles. Remove all loose particles of collodion from the plate by gentle brushing when the drawing is completed. Immerse the plate a second time in the silver bath, and develop with either pyrogallic acid or sulphate of iron developer.
Husnik proposes to first coat the plate with a solution of pure fuchsin, and afterwards with one of gum, and then engrave as previously indicated.[Y]
[Y] Major Waterhouse has published the following ingenious method of transforming a drawing on paper into a photographic negative:—“A tracing, or drawing, is made in lithographic ink on tracing paper, using plenty of ink on the lines. The drawing is then placed on a board over a piece of blotting-paper, and brushed all over with a strong solution of aniline brown in water; when dry it is rubbed over with a tuft of cotton wool soaked in turpentine, which removes the ink without altering the coloured ground. The lines then appear clear on a dark reddish brown ground. The negatives thus obtained are good, but more suited for coarse than fine work.” It may be suggested, why not transfer the drawing direct to stone, and produce the necessary copies by lithography?—Trans.
By either of these methods negatives of extreme density and absolute clearness in the lines may be produced and used for obtaining impressions in ink, the transfer of which to stone presents no difficulty.
It remains to be added that there are several methods of producing grained negatives for photo-lithography in half-tone, and therefrom a transfer for stone, and so obtaining impressions at a much greater rate than is possible from a Collotype plate. They may each produce results with a certain amount of success; but even those from the best methods indicated cannot be compared with Collotype. The too obtrusive grain of the half-tone pictures so produced destroys much of the finer details, and it is to be regretted that all such processes leave so much to be desired.
APPENDIX.
THE STEAM COLLOTYPE MACHINE.