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

25. F. CJrbach, "Thermography," Phot. J., 90S, No. 4: 109-114, July 1950; Thermojax, leaflet published by Minnesota Mining & Mfg. Co., St. Paul, Minn. Discussion Wm. H. Ojfenhauser (Consultant): In among some old film clips that I had a number of years ago, there was a strip of diazo process film that was printed in France. The picture was Dreyfus. I lost its history from that point on. I wonder if you can tell us why the thing died or why it might have started at all. Thomas T. Hill: There was a lot of promise in that process. Of course, the diazo system is promising because you have colors there and they thought they could make use of it. Also it's nongelatin. Actually the sensitive material is cast right into the base, whether it's a celluloid base or a cellophane base. Most of the sound-track methods were on a cellophane base like the Philips diazonium process. One of the drawbacks was that you did not have the dimensional stability and the overall usefulness of your prints running as many hundreds or thousands of times as does a good print from material we use now. Another trouble was that these diazo dyes were not as light stable, and after projection a few dozen times the image began to fade. It's very difficult to get good fixing with diazo materials — so nothing intensifies or darkens, and so that the dyes do not fade. That seems to be why that thing has fallen by the wayside up to now. There's still enough promise, I think, to continue with it, but it isn't as good as was hoped for in the beginning. Anon: Is there anything in the literature that would indicate the problems of sound recording on these nonsilver media? Mr. Hill: That was one of the applications that the Philips diazonium process was aimed at, because of its terrifically high resolution — they thought they could get a better sound track. But when I talked to the men who had worked on it in this country they told me that they had found several things wrong with the thing as developed in Holland and sent it back for further research. One of the troubles was that they spent all of their time working on a material on a cello phane base. Because of the very thinness of the material they could put a big reel of film with sound track on a very small area, but the people in this country pointed out that the dimensional stability of the cellophane wasn't up to what we're used to in the motion picture industry and it just simply wouldn't work for that reason. The other thing was, of course, the mercury involved a health hazard which they apparently hadn't realized. So it has gone back to Holland for work with the cadmium aspect of the system and Dr. Jamieson of the Philips Laboratories in Irvington-on-Hudson, New York, told me recently that there's some promise that they'll come back again with better results for that specific purpose on sound track. Anon: So the summary is probably that Eastman Kodak and du Pont and Ansco can continue to make film for a little while? Mr. Hill: For quite a while. Anon: Until the magnetic boys catch up with them. Mr. Offenhauser: I'd like to bring in a little more history at this point. Just before World War II when I was with John Maurer we were working with a wide-range silver film master record recording system for frequency modulation broadcasting. We used Class A pushpull, direct-positive recording on yellowdyed silver film with galvanometers that peaked at 22 kc and with a film speed of 60 ft per min. The direct-positive was printed in diazo material by Agfa-Ansco at Binghamton. We made prints on diazo material and the objective at that time was to use the prints from these records for FM stations as transcription record material on account of the fact that we found very low distortion levels in the diazo prints from the silver originals. I mention this as a matter of history. Mauro ^ambuto (Scalera Films, Rome, Italy): One advantage of those diazo films was that they scratched less in some aspects of them. In connection with the soundtrack use of the diazo materials, I wish to say that I also had some experience with that particular film that was made in France, and incidentally it was Dreyfus. That was back in 1939. Now, there was one major problem at the time due to the Thomas T. Hill; Npnsilver Photographic Processes 65