DRAWINGS MADE FROM PHOTO GRAPHS There are many methods of making line drawings from photographs, and most of them involve the destruction of the originals. In essence, the lines of the photograph are gone over with waterproof ink and the photograph then bleached. Matt prints on bromide, gas light, or P.O.P. paper may be used, the last mentioned being fixed and washed, but, if it can be avoided, not toned. The ink used must be waterproof, Indian or Chinese, applied in any convenient manner, as, for instance, with an ordinary pen, a mapping pen, a camel-hair pencil, etc. When sufficient work has been put on the print, the photographic basis is entirely destroyed with a powerful solvent of the silver image. Any reducer or bleacher may be used, but in practice one that acts quickly and without stain has its advantages, and therefore a mixture of iodine and potassium cyanide, both of which are poisonous, is the best. The formula is :— To % solution of iodine in methylated spirit 6o drops rz5 ccs.
To % solution of potas sium cyanide in water . . . To „ 21 „ Water . . I oz. T,000 „ This may be used stronger if the action is not quick enough. The solution should not be allowed to touch the fingers any more than is unavoidable. The mixture ought to destroy the photograph in half a minute ; the picture is then washed for five minutes and afterwards dried.
The following process is used by many trade workers : Make ordinary prints on a smooth surface bromide paper, exposing and developing in the usual way ; after developing, harden in an alum bath, wash and dry, but do not fix. Then draw over the picture with good water proof Indian ink, and when the latter is quite dry bleach in a copper-bromide bath made by dissolving 5o grs. of potassium bromide in i oz. of water, 5o grs. of copper sulphate in another ounce of water, and mixing the two solutions together. If after bleaching the draw ing requires further working up, it may be well washed and redeveloped with any weak dry plate developer, dried, worked on, and again bleached. After a good rinse the bleached image may be totally destroyed, and the lines left permanently black upon a white ground by passing the bleached print through a potassium cyanide or " hypo " bath. A saturated solution of mercuric bichloride may also be used for bleaching out the silver image. When the
results are required for use as originals in line photo-engraving, the bleached prints should be kept from the light as much as possible, or they may turn yellow.
A simpler process of drawing on a photographic base is that of using a blue (ferro-prussiate) print, preferably one that has not been made too dark by over-printing. As the light blue colour will not photograph, the drawing may be repro duced by line photo-engraving processes without any bleaching, although the blue image can be removed, if desired, by immersing in dilute liquor by a prolonged washing in hard water, or better and quicker still, by immersing in a solution made by dissolving T part of potassium oxalate in 6 parts of water. Solutions of sodium carbonate and caustic potash will also bleach blue prints.
In process work, various methods are adopted for making drawings from photographs. If the photograph is mounted, and must not be removed from the mount, it is best to lay over it a piece of tracing gelatine, scratch the out line with a sharp point, and then to rub black lead or red chalk into the lines. This draw ing is turned face down on to a sheet of Bristol board, or other surface to be drawn upon, and rubbed down with the handle of a tooth-brush, or by other convenient means. The drawing is in this case reversed. It may be obtained the right way by re-scratching on the back of the gelatine and filling in this side instead of that originally traced, or it may be reversed by means of prisms when making the block.
A better way is by the use of the " Norwich Film," a gelatine with a matt surface which can be drawn on with pencil, crayon, or ink. The resulting drawing may be used as a photographic positive, or may be converted into a negative by flowing with a non-actinic varnish. When dry, the greasy ink or crayon is removed with benzole or other suitable solvent.
The bleaching-out process, already described, is perhaps the best way of converting a photo graph into a drawing.
Unmounted prints may be traced down on to Bristol board or drawing paper by rubbing the back with blacklead or red chalk, or by putting common transfer paper between the print and the drawing surface. The outlines of the photograph are then gone over with a hard pencil or stylus.