CHAPTER I
PRODUCTION OF THE BROMIDE PRINT
Table of Contents Failures in the bromoil process in the great majority of cases can be ascribed to the fact that the basic bromide print was not satisfactory. Therefore the method of preparation of the bromide print or enlargement deserves the most careful consideration, for the bromide print is the most important factor in the preparation of a bromoil print. The beginner, especially, can not proceed too carefully in making his bromide print.
Because of the extraordinary importance of this point, we must first define what is here meant by a perfect bromide print.
In deciding how to produce a satisfactory bromide print as a basis for a bromoil, we must exclude from consideration esthetic or artistic grounds.
The bromide print must be technically absolutely perfect, that is, it must have absolutely clean high lights, well graded middle tones, and dense shadows. Especial stress must be laid on the brilliancy of the high lights. It is best to compare these high lights with an edge of the paper which has not been exposed and is not fogged or, even better, with the back of the paper. The highest lights should show scarcely a trace of a silver precipitate and must therefore be almost as white as the paper itself. Negatives which do not allow of the production of prints as perfect as this should not be used while the bromoil process is being learned.
This apparently superfluous definition of a perfect bromide print has to be given in this way, because it only too often occurs in practice that the worker himself is not clear as to what is meant by the expression, perfect bromide print. This may be partly ascribed to the fact that the silver bromide process-whether rightly or wrongly need not be determined here-has not been properly appreciated among amateurs who are striving for artistic results. Bromide printing has frequently been considered not to be satisfactory as an artistic means of expression, and has therefore been considerably neglected. In many quarters it is considered as just good enough for beginners.
Nevertheless, the bromide process is per se an uncommonly flexible method and gives, even with a very considerable amount of overexposure or underexposure, that is, even when very badly handled, results which are considered usable. It is even possible that an improperly made bromide print, one for instance, which is soft and foggy, might in some circles be considered as esthetically more interesting than a perfect print. This is an undeniable advantage of the process. It may also become a danger, if an imperfect bromide print is used as a starting point in the bromoil process. If anyone is not sure on this point, let him compare his own bromide prints with such samples as are frequently shown by manufacturers in window displays and sample books. He will then see what richness of tones and wealth of gradation are inherent in the process. If, however, an imperfect silver bromide print is used as a starting point for a bromoil, it can not be expected that the latter will display all the possibilities of this process. If the bromide print is muddy, the work of inking will be difficult, and it will be impossible to obtain clean high lights. If it is underexposed and too contrasty, it can not be expected that the bromoil will show details in the high lights which were lacking in the bromide print. If the worker himself does not know that his silver bromide print is faulty, he is inclined to ascribe the difficulties which he finds in making the bromoil print and his dissatisfaction with the results, to the bromoil process itself. Most of the unsatisfactory results in bromoil work must be ascribed to the imperfect quality of the bromide print which is used, and this is the more important as this lack is not perceptible to the eye after the bleaching is completed. Whoever, therefore, desires to successfully practice bromoil printing, must first decide impartially and critically whether he actually knows how to make bromide prints, and must acquire full mastery of this process.
The technically perfect bromide print made from a properly graded negative can, as will later be described, have its gradations changed in the bromoil process without any difficulty, and thus be made softer or more contrasty. The advanced bromoil printer who is a thorough master of the technique of the process will therefore easily be able to work even with poor negatives; when making his bromide prints from such negatives, he will consider the ideas which he intends to incorporate in the bromoil print and will make his bromide print harder or softer than the negative and at the same time retain the necessary cleanness of the high lights.
The best starting point for a bromoil print, however, especially for the beginner, is and must be a bromide print as nearly perfect as possible.
A suggestion for the certain obtaining of such prints may be added here. When we are working with a negative with strong high lights, judgment as to the freedom of the bromide print from fog by comparison with an unexposed edge is not difficult. This is not the case with negatives which show no well marked high lights. In such cases it is advisable to determine what is underexposure by making test strips in which details in the high lights and middle tones are lacking and, working from this point, determine by gradual increase of exposure the correct time which gives a perfectly clean print.
The Choice of the Paper.-One of the most important problems is to find a suitable paper for the process. Not all of the bromide papers which are on the market will give satisfactory results. It is only possible to use papers whose swelling power has not been too completely removed in process of manufacture by the use of hardeners. The principle of the bromoil process is that a tanning of the gelatine shall occur simultaneously with the bleaching of the silver bromide image. As we have already remarked, this does not affect the high lights and leaves them still absorbent, while the shadows are tanned and therefore become incapable of taking up water. The half-tones are tanned or hardened to an intermediate degree and therefore can take up a certain amount of water. Therefore, in place of the vanished silver image, we get a totally or partially invisible tanned image in the gelatine film.
The variously hardened parts of the gelatine film, corresponding to the various portions of the vanished bromide image, display the property acquired through different degrees of tanning by the fact that the portions of the gelatine which remain unhardened and which correspond to the high lights of the silver image formerly present, absorb water greedily. Consequently they swell up and acquire a certain shininess, because of their water content; in addition they generally rise above the other parts of the gelatine film, which contain little or no water, and give a certain amount of relief when they are fully swelled. The portions of the film in which the deep shadows of the bromide image lay are completely tanned through, can therefore take up no water, and remain matt and sunken. This graded swelling of the gelatine film becomes more apparent, the higher the temperature of the water in which the film is swollen.
If, however, the paper was strongly tanned in the process of manufacture, the gelatine has already lost all or most of its swelling power before it is printed and, although the bleaching solution in such cases can indeed remove the silver image, it can no longer develop the differences of absorptive power which are necessary for a bromoil print; for, although the bleaching solution can harden an untanned gelatine layer, it cannot bring back the lost power of swelling to a film which is already hardened through and through.
Therefore bromide papers which have already been very thoroughly hardened in manufacture show no trace of relief after bleaching, and very slight, if any, shininess in the lights. This is the case especially with those white, smooth, matt, heavyweight papers which are especially used for postcard printing. When such papers are taken out of the solutions, as a rule, these run off quickly and leave an almost dry surface. It is generally not possible to make satisfactory bromoil prints on such papers. It is true that the image can be inked by protracted labor; it is, however, muddy and flat and, as a rule, cannot be essentially improved even by the use of very warm water. Other types of bromide paper which have not been so thoroughly hardened may show no relief after bleaching, yet, after the surface water has been removed, they do show a certain small amount of shininess in the high lights when carefully inspected sidewise. With such papers the necessary differences of swelling can generally be developed if, as will later be more completely described, they are soaked in very warm water or in an ammoniacal solution. It is rare to find in commerce silver bromide papers which have not been hardened at all, or only very slightly hardened, in their manufacture. Such papers, because their films are very susceptible to mechanical injury, are not likely to stand the wear and tear of the various baths. On the other hand, as a rule, they usually produce a strong relief even in cold water, and therefore tend to produce hard prints. The greatest adaptability for bromoil printing may be anticipated from bromide papers which are moderately hardened during manufacture.
To determine whether a given brand of bromide paper is suitable for bromoil work, an unexposed sheet of the paper should be dipped in water at a temperature of about 30° C. (86° F.) and the behavior of...
