Cinematographic annual : 1931 (1931)

386 CINEMATOGRAPHIC ANNUAL in any larger quantity for use in larger tanks. Incidentally, the chemical type of reversion does not require a solid drum developing system. With regard to the processing of reversal film by individual amateurs, most of the manufacturers state that while the methods outlined above will work with their products, they do not recommend individual processing, as an individual is rarely equipped to exercise the same exact control of all operations that the regular processing stations do. If an individual feels it is necessary to process his own film, the manufacturers point out that far more satisfactory results can be obtained by developing the film (reversal or otherwise) as a negative and subsequently making prints from it. dupois Metric ounces 2.0 liters grains 1 .2 grams ounces 1 60.0 grams grains 24.0 grams ounces 75.0 grams grains 3.6 grams grains 2.8 grams grains 6.0 grams gallon 4.0 liters C) MOTION PICTURE DEVELOPER (Negative or Positive Film) A voir Water (about 125° F. ) (52° C.) 64 Elon ... 17 Sodium sulphite (E. K. Co.) 5 Va Hydroquinone _ — 3 SO Sodium carbonate (E. K. Co.) 2Vi Potassium bromide 5 0 Citric acid 40 Potassium metabisulphate ... 8 5 Cold water to make 1 Average time of development 7 to 1 5 minutes at 65° F. (18° Fine Grain Developers for Motion Picture Negative Film The following formulas have been found to give finer grained images than any other commercially used developer and are recommended for the development of ordinary and panchromatic negative film. With use, these developers may become slightly muddy but this is due to a suspension of colloidal silver which is likely to form and which is harmless and may be ignored. The tank usually becomes coated with a thin white deposit of silver but this does no harm. Formula D-76 A B Elon 120grains 160 grains Sodium Sulphite (E.K.Co.) 11 ounces 14 ounces Hydroquinone 300 grains 160 grains Borax 120 grains 120 grains Water 128 ounces 1 Gallon 128 ounces Temperature of developer 65° F. "A" developer will give a little more snap in quality — while the ,lB" developer will give a softer quality negative. Directions for Mixing: Owing to the high concentration of sulphite in the formulas, it is somewhat difficult to dissolve all the chemicals unless directions are followed carefully. First dissolve the Elon in a small volume of water (about 125° F.) and add the solution to the tank. Then dissolve approximately one quarter of the sulphite separately in hot water (about 160° F.) and add the hydroquinone with stirring until completely dissolved. Add this solution to the tank. Then dissolve the remainder of the sulphite in hot water (about 160° F.) add the borax, and when dissolved pour the entire solution into the tank and dilute to the required \oluine with cold water. The development time varies with the number of feet which have been processed but the average time for a fresh bath is from 10 to 15 minutes at 65° F. If a slower working developer is required the quantity of Elon, hydroquinone and borax should be reduced. To obtain a faster working developer, increase the quantities of these chemicals. The life of the developers is practically the same as that of the usual Elon-pyro motion picture developer in general use. An idea of the increase in development time with use may be gained from the fact that after 25,000 feet of film have been processed per 300 gallons of developer the development time is practically doubled. The developers may be revived once or twice during their life by the addition of half the quantity of borax originally used in the formula. These developers are somewhat sensitive to the effect of sodium bromide produced by the conversion of the silver bromide in the processed film to metallic silver. A comparatively fresh solution is therefore necessary for developing extreme underexposures. With average studio exposures, however, excellent negatives can be obtained even with the partially exhausted developer.