Bromoil printing and bromoil transfer

by Emil Mayer

If the bromoil is to be kept for future work, then it should be allowed to become bone dry, in order to dissolve off any grease with benzol or other solvent, exactly as is done with a bromoil print in defatting. Prints thus treated can be used again after any lapse of time.

This method of printing is proper for either monochrome or polychrome impressions.

In conclusion the fact may be mentioned—first published in France, I believe—that bromoil prints, which in the course of making have been soaked in ammonia water, can be more easily transferred, and that there is less danger of the bromoil print and the paper sticking together, even with very strongly absorbent papers.

Robert Demachy has stated that transfers can also be prepared by removing the ink, not by a press, but with a solvent, such as benzol, by moistening the paper with this solvent and then bringing it into contact with the pigmented bromoil. My experiments in this direction could not be brought to a conclusion, as at the time I undertook them a suitable solvent was not available. I had only succeeded in determining that it is very important that the bromoil print should be allowed to dry thoroughly—from six to eight hours—and that then a less volatile solvent than benzol, such as heavy benzine, or best of all, gasoline or petroleum ether, can be used. If the bromoil print is laid on a sheet of paper and moistened with this, then pressure in a printing frame is sufficient in order to obtain a transfer. A machine is not required.

The pictures which I have obtained in this way have not been satisfactory, up to the present time; the cause of the failure obviously was that I lacked experience as to the necessary degree of moistening and the duration of contact. As stated, for lack of materials, I was obliged to discontinue experiments.

Combination Transfer.—The process just described permits the transfer of all that was in the bromide print. If, however, it is a question of improving the inadequate gradation of a bromide print from a long-scale negative, we must use other means. Bromide paper has only a limited scale of tones and therefore cannot reproduce the full modulation of a negative of full gradation. If the details in the shadows are to be retained in such a case, then the high lights will appear bare; if well-modeled high lights are desired, then we risk blocked-up shadows.

This difficulty has been largely overcome by Dr. Emil Mayer, by the introduction of a combination printing process for bromoil transfer, of which full details will be found on [page 125]. He starts from the above-mentioned fact that bromide paper does not reproduce the whole scale of tones of the negative, when this is too long, and therefore divides the tones of the negative into two parts by exposing one bromide print only for the shadows and the adjacent half-tones, and a second merely for the high lights and the lighter half-tones. He then transfers these two constituent prints in superposition and thus obtains the full gradation of the negative. It is thus possible therefore to lengthen the scale of tones of the negative. If, however, it is merely desired to extend the scale of tones of the bromide print, then it is sufficient to make the combination transfer from one print only, which must, however, be prepared in a way differing slightly from the usual.

I will not repeat here the theory of the two kinds of combination transfer, which may be found in an earlier chapter by Dr. Mayer ([page 125]), but in giving my own instructions for the practical performance of the process, I have essentially adhered also to Dr. Mayer’s instructions, with his full permission.

Combination Printing from Two Bromoils.—It has frequently been pointed out in the literature of the gum process that the best positive transparencies may be obtained from a long-scale negative by making two positives from the one negative and then bringing these two positives into superposition; for this combination, one positive must be fully exposed and developed soft, the second, on the other hand, kept hard by a very short exposure and full development. If these two positives are laid film to film, “there is obtained,” as von Hübl wrote as early as 1898, in applying this method to gum printing (see Eder, Das Pigmentverfahren, der Gummi-, Oel- und Bromöldruck, Halle, 1917), “a result which often surpasses, in truth and fidelity to the original, a normal print from the negative. In such a combined print the high lights are derived from the short, the shadow details from the long-scale negative; the two images supplement each other and reciprocally increase the brilliancy. It is also possible to make good defects in the negative or the printing process.”