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Ansco 351 Pinakryptol Green Desensitizer

FormulasThis solution is suitable for treatment of exposed films previous to development, to permit increased darkroom illumination and greater safety for film inspection during development.


Pinakryptol Green 1 g
Water to make 500 ml


Note – Use of a 50/50 water-alcohol mixture for solution will improve the keeping qualities of the desensitizer.


For use, dilute 1 part stock solution with 10 parts water. Immerse films for two minutes at 68F (20C) with room in total darkness, and then transfer to developing solution. After one half of the developing time, films may be inspected for 10-second periods at one-minute intervals; illumination being supplied by a yellow-green safelight (such as Ansco A6 with 10-watt lamp) placed 2 to 3 feet distant. Desensitized films should be developed approximately 50% longer in Ansco 17 or Ansco 47 than non-treated films to obtain comparable gradation and shadow detail.


If preferred, the same stock solution may be used directly in the developer in the proportion: 1 part desensitizer, 30 parts developer. This procedure should not be followed with developers containing more than 1 gram per liter (15 grains per quart) of hydroquinone.


From Ansco Formulas for Black and White Film by GAF, 1948 – Formulas are provided for historical reference. They may not work well with modern films and papers. Some of the chemicals can be dangerous. As with all photographic processes, be careful.