Journal of the Society of Motion Picture Engineers (1930-1949)

some of the dye-bleach color systems such as early Caspar color. In a few cases the low sensitivity is not so important. But where the sensitivity has been even somewhat increased, the cost of the material is no longer low, and therefore such a system is less competitive with the silver-salt process than it was originally. Of course, in auxiliary aspects of our work, some of the nonsilver processes can be used but not in a direct, motionpicture-taking application. But what of the future? Can some of these processes come up to the overall advantages of the silver process? A close study of the literature in a number of these cases, and first-hand experience with a number of these processes in the laboratory, indicate that they have a long way to go before any of them could successfully challenge silver for more than a small part of silver's great range of usefulness. For example, we have had an opportunity to watch an investigation recently of claims to a new process by which the sensitivity of a diazo dye process was to be increased to equal that of silver materials. When it was finally boiled down it was found that the sensitization simply did not work. Applied to textiles, this special type of diazo process was quite practical, but it required terrifically long exposures or exposures to extremely bright light at very close range, and it required exposure of the material while wet. So, another hopeful method of speeding up one of the nonsilver processes went by the board. In general, our present conclusion must be that none of these other processes is likely to become competitive to the silver process in the near future, for our purposes. In some specialized fields, such as photocopy work, and other cases where high exposure speed and good tone range are not necessary, there is great hope that some of these methods will give results equal to that given by silver emulsions at lower costs and with simpler processing techniques, but with the very high requirements of the motion picture art, we of this group cannot expect much from any of these "new" systems for a long time to come. Therefore our major efforts at present should be expended on improving the processing technique of the silver process in order to simplify it, and lower the cost. Some of these methods appear to be very promising, such as the stabilization techniques to replace the fixing and washing stages of normal silver processing. The use of higher temperatures, spray processing procedures and other improvements in this aspect, will decrease some of the few disadvantages of our familiar and very successful silver light-sensitive process. Bibliography D. A. Spencer, Ed., Progress in Photography, 1940-1950, Focal Press, London and New York, 1951. M. M. Eder, History of Photography, translated by E. Epstean, Columbia University Press, New York, 1945. K. H. Saunders, The Aromatic Diazo Compounds and Their Technical Applications, 2nd ed., Edw. Arnold & Co., London, 1949. J. Friedman, History of Color Photography, American Photographic Publishing Co., Boston, 1942; and his monthly columns in American Photography in the 1930's and 1940's. Edward K. Kaprelian, "A survey of photographic processes and materials," Phot. Eng., 7, No. 2: 42-55. (This includes an extensive bibliography of 80 items.) J. W. Mitchell, Ed., Fundamental Mechanisms of Photographic Sensitivity, Butterworth's, London, 1951. B. de Goster, "The principles and possibilities of diazo-copying processes," /. Documentation, 5: 1-11, June 1949. S. C. Slifkin, "Status of developments in the German diazotype reproduction process," FIAT final Report No. 1082, May 2, 1947; PB Report No. 78,256. (These are published by agencies of the U.S. Dept. of Commerce, Washington 25, B.C.) Thomas T. Hill: Nonsilver Photographic Processes