Pressurized High-Speed Development of Diazo Films

The combination of a new high-speed process and developer unit which uses pressurized anhydrous ammonia gas offers a significant increase in the speed of developing diazo photomaterials. In addition to being up to 100 times faster than conventional ambient-pressure ammonia development processes, the new process and developer provide both flexibility and uniformity of sensitometric characteristics. The unpleasant odor and corrosive character of ammonia gas required a means for positively sealing the film surface to the processing device and a means for disposing of residual ammonia gas remaining in the device at the end of the processing cycle. A developer platen, designed to meet these needs, also achieves uniform image development by utilizing the entering flow of ammonia gas to wash entrapped ambient air from the film surface and into a small reservoir. The process and its relatively simple hardware have been incorporated into an experimental photo-image converter to provide “on-line” input and output of photo-images from a random access image file. The process and a wash-type developer are used in the IBM 9950, 9954 and 9955 diazo aperture card copiers.