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Development of MotionPicture Positive Film by Vanadous Ion
By A. A. RASCH and J. I. CRABTREE
The inorganic developer system of Roman, employing divalent vanadium ion as the active developing agent, has been further investigated. A solution prepared from vanadium pentoxide, sulfuric and hydrobromic acids, and reduced by electrolysis was found to double the speed of motion-picture positive emulsions with development times of the order of 20 sec at 60 F. Other sensitometric properties can be controlled to match those produced by conventional processing. A motion-picture film-processing machine employing the vanadium developer has been devised and tested and is described. Developer activity is maintained by continuous electrolytic regeneration of the solution, with replenishment made only to balance carryover losses.
Early Work
Photographic developers which employ a metal ion as the active developing agent have been known for a long time. Perhaps the most well-known system is that using ferrous iron.1 Others, using chromium,2'3 tungsten3 and molybdenum,3 have been investigated to a lesser extent over the past sixty years. Some work has also been carried out with metal-ion systems in which the metal ion is tied up with a chelating agent, and a recent paper describes the use of trivalent titanium in such a system.4 From a practical standpoint, none of the
Communication No. 1616 from the Kodak Research Laboratories, by A. A. Rasch and J. I. Grabtree, Research Laboratories, Eastman Kodak Co., Rochester 4, N.Y. The paper was presented on October 6, 1953, at the Society's Convention at New York. (This paper was received October 2, 1953.)
developers investigated were found to be of much interest because of their low activity, very short exhaustion life, and poor stability.
Divalent vanadium has also been known to have photographic activity as early as 1894, when A. and L. Lumiere5 described the preparation of a vanadium developer solution. However, the Lumieres were more interested in the use of vanadium salts as the lightsensitive material in printing out emulsions and did not fully investigate the use of vanadium in developers. Subsequent reference to vanadium as a developing agent6 gives very little experimental data.
Recently a French photographic chemist, Pierre Roman, initiated a new series of investigations of the metal-ion developer system.7 He calculated that any metal-ion system having a standard reduction potential more negative than
January 1954 Journal of the SMPTE Vol.62