Bromoil printing and bromoil transfer

by Emil Mayer

I might describe here another process for obtaining clouds, because it is especially suitable for the bromoil process. If there is no object in the negative which is cut by the upper edge of the plate, it is extremely easy to introduce clouds into such a landscape, and at the same time lengthen out the picture at the top. A cloud negative suitable for the landscape is chosen, and the relative exposures for the landscape and clouds found as accurately as possible by test strips. The landscape negative is then focused on the enlarging screen so that there is plenty of paper above the upper edge of the plate, and then the exposure is made while the upper part of the paper is covered with a card, which is kept moving constantly between the light source and the enlarging screen, so that the upper edge of the plate is not imaged on the screen. After the exposure is finished, the paper is shifted down on the screen until the upper edge of the paper comes at the place which was previously occupied by the edge of the plate, the landscape negative is changed for the cloud negative, and the clouds are exposed on the upper and hitherto unexposed part of the enlarging paper, while the landscape is protected from exposure by means of a piece of card, shaped like the previous one for the sky, and continually moved to avoid a sharp line of separation. In the subsequent development a perfectly uniform picture is obtained, in which there should be no visible trace of its compound nature.

Obviously, in the preparation of the bromoil print, it is advisable to employ to the utmost the many possibilities which bromide printing offers. Thus too thin parts of a negative may be held back by proper blocking out on the back and numerous other possible modifications, which have been described in textbooks and technical journals, but which cannot be further dealt with here, may be profitably employed.

Fixation.—The developed bromide print should be well rinsed and fixed in the usual way. If the rinsing is omitted or is too superficial, complete or partial reduction phenomena may occur in the fixing bath, and make the print unusable.

The bromide print should be left in the hypo solution for about 10 minutes, and care should be taken, if several prints are simultaneously treated, that they do not stick to one another. Then should follow thorough washing for removal of the hypo; if traces of hypo remain in the film, the subsequent bleaching is rendered more difficult, as the image does not disappear but only turns brownish. While it is feasible to subject the bromide print to the bleaching process, as soon as it comes from the washing, an intermediate drying is an advantage; for the gelatine gains greater resistance by this drying.

CHAPTER II
THE REMOVAL OF THE SILVER IMAGE

Bleaching.—The bleaching process has the purpose of making the bromide print, correctly prepared according to the previously described method, suitable for the bromoil process. To this end the silver image must be made to disappear and in its place that condition of the gelatine produced which renders it possible for it to take up the greasy ink. The bleaching solution has, therefore, two functions: it must remove the metallic silver, imbedded in the gelatine film, which forms the bromide image, and at the same time cause a tanning of the gelatine film corresponding to the image that disappears. In the place of the silver image there then exists an invisible tanned image in the gelatine film.

There are a large number of chemical compounds known to photographic technique, which enable us to dissolve out the metallic silver imbedded in the gelatine film. Such are, for example, the many reducers which have found practical application. Many of these chemicals also cause changes in the gelatine simultaneously with the solution of the silver. But not one of the hitherto known bleaching solutions possesses the double power required of it: solution of the silver image and corresponding tanning of the film. Some produce too great a tanning which acts upon the whole film, and the result in inking-up is muddy flat prints, which do not lend themselves to artistic modification. With other bleaching solutions a differential tanning of the gelatine is produced, but at the same time they so alter the surface of the gelatine that it becomes glossy all over, and only takes even soft inks with difficulty.

My experiments have led to the compounding of a bleach which completely fulfils the requirements set for it; the silver image is quickly and completely removed, while simultaneously a tanning of the film, strictly analogous to the disappearing image, is effected; easier and more certain inking-up is rendered possible, and besides this the advantage is obtained that the differences of relief, produced in the gelatine by the bleaching process, can be influenced to a wide degree by varying the temperature of the water. The composition of this bleaching solution, which prepares the gelatine film in the most perfect manner for the bromoil print, is as follows, three stock solutions being required: