Bromoil printing and bromoil transfer

by Emil Mayer

These facts can only be explained by remembering that the positive processes, which were available to photographers and with which they had to be satisfied, were rather numerous and offered a considerable variety of effects. Nevertheless, a single characteristic was common to all previously known photographic printing processes—their inflexibility. Each of these processes, in spite of its individual peculiarities, could do nothing more than exactly reproduce the negative which was to be printed. It was possible to produce certain modifications of the negative image as a whole, by printing it darker or lighter, or by using a harder or softer working process. Changes on the negative itself for the purpose of giving a more artistic rendering must, however, always be very carefully thought out in advance and effected by retouching, often difficult and not within the power of every photographer, or by other methods which change the negative itself. If such modifications of the negative proved unsuccessful, it was irreparably lost; if they succeeded, the plate, as a rule, could no longer be used in any different manner. The possibility of undertaking radical changes which might realize the artistic intentions of the worker on the print itself, in order to save the negative, and especially of planning and carrying out the deviations from the original negative, which expressed the worker’s artistic feelings, during the printing, was not afforded by any previously known printing methods. A single exception was found in gum printing, if the production of the image was divided into a series of partial printings. Each of these phases, however, was in itself incapable of modification except for the possibility of doing a certain small amount of retouching; nevertheless, by means of efficient management of the single printings and by properly combining them, beautiful artistic effects could be obtained. This, however, required an extraordinary amount of practice and skill, and a very considerable expenditure of time, and it must also be remembered that the failure of one of the last printings often destroyed all the previous work. Also, in gum printing, to have a reasonable expectation of success, the work must be thought out from the very beginning and carried out in exact accordance with a plan from which it was scarcely possible to deviate during the work, even when it became apparent that the desired result could not be satisfactorily obtained.

The possibility of planning results during the course of the printing and carrying them out directly on the print itself did not previously exist.

The first process to bring us nearer to this ideal and make possible a freer method of working was oil printing. The technique of this process consisted in sensitizing paper which had been coated with a layer of gelatine, by means of a solution of potassium bichromate, and of printing it under the negative. The yellowish image was then washed out; the bichromate had, however, produced various degrees of tanning of the gelatine, corresponding to the various densities of the silver deposit in the negative. The lighter portions, which had been protected from the action of light by the dense parts of the negative, retained their original power of swelling and could therefore later absorb water. The shadows, however, corresponding to the transparent parts of the negative, were tanned, had lost their absorptive power, and had become incapable of taking up water. Consequently, the high lights swelled up fully in water, the shadows remained unchanged, and the middle tones showed various degrees of swelling corresponding to the gradation of the negative. If the print was blotted off and greasy inks spread upon it by means of a properly shaped brush, the inks were entirely repelled by the swollen high lights which had absorbed water, and completely retained by the fully tanned shadows, while the middle tones, in proportion to the amount of tanning, retained or repelled the greasy ink more or less completely.

In this process, for the first time, there was found a possibility of changing various parts of the image absolutely at the worker’s will, even during the progress of the work. By the use of harder or softer inks it was possible to color the swollen high lights more deeply, or to hold back the shadows so that they did not take up all the ink that was possible. It was possible to leave certain parts of the print entirely untouched and work up other parts to the highest degree; in short, oil printing opened the way to free artistic handling of the print.

Thus, the oil process was the first photographic printing process in which we were completely emancipated from the previous inflexibility which ruled in all printing.

Nevertheless, a number of disadvantages attach to oil printing which hinder its general use. The most important shortcoming of this process is that bichromated gelatine as a printing medium can only reproduce a comparatively short scale of tone values. The production of prints from contrasty negatives is therefore impossible, for the shadows are much overprinted before details appear in the high lights, or on the other hand, there is no detail in the lights if the shadows are fully printed. This difficulty can be only partly overcome by the most skilful use of inks of various consistency. It is indeed possible to ink up the lights by the use of very soft ink, but this does not replace the missing details; and overprinted shadows, which it is tried to improve by keeping down the quantity of ink applied, appear empty. Thus it happens that most of the oil prints yet exhibited show a certain muddy family likeness, which, at first, when the process was new, was considered to be advantageous on account of the novelty of the effect, but later received deserved criticism. A second disadvantage of the oil print is the fact that it is not possible to observe the progress of the printing on the bichromated gelatine film. The brownish image on a yellow background is very deceiving, and it is usually necessary to determine the proper amount of printing for each individual negative by actual experiment, and to make additional prints by means of a photometer.

Another inconvenience of other previously known printing processes, to which oil printing is also subject, comes from the fact that the great majority of negatives are now made with small cameras. On account of the extraordinary perfection of modern objectives, the small negatives produced by modern hand cameras can be enlarged practically without limit. The advantages of a portable camera are so considerable that large and heavy tripod cameras have practically gone out of use, except for certain special purposes. On the other hand, however, direct prints from small negatives are, as a rule, entirely unsatisfactory from an artistic standpoint. If we desire to use any of the previously mentioned positive processes, including oil, to produce artistic effects, we must first make an enlarged negative. This requires, in the first place, the production of a glass transparency from the small negative, from which we may prepare the desired enlarged working negative.

Various workers held various views as to whether this requirement were a help or a hindrance, but it was universally accepted as a necessity. The way from the plate to the enlarged negative, nevertheless, always remained uncertain, tedious, and expensive. Simple as it may appear to be, it includes a whole series of stages where it is possible to come to grief. At every single step lurks the danger that undesired changes of gradation in the negative may result from inaccuracy in exposure and development, from the use of improperly chosen sensitive material, and from various other causes, and even if these factors are all correctly handled, there is still an unavoidable loss of detail. Therefore the path from the small original negative to the enlarged negative necessary in previously used processes is neither simple nor safe.

Naturally it was also necessary to travel this wearisome path in working the oil process, when it was desired to make large prints from small negatives.