Fixer Sulphite Level for PMK

Discussion in 'B&W: Film, Paper, Chemistry' started by Josef Guay, Mar 14, 2004.

  1. Josef Guay

    Josef Guay Subscriber

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    I ran out of TF-4 the other day so I mixed up a batch of sodium thiosulfate with ammonium chloride to speed up the fixing process. The fixer worked well on paper and I would like to use the same fixer for film.

    Most recipes that I have found for sodium thiosulfate fixers have 15 grams per liter of sodium sulfite. The few ammonium thiosulfate seem to have lower levels of sulfite.

    Should I lower the level the sulfite level so that I don't weaken the staining action of the PMK?
     
  2. john_s

    john_s Member

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    I've read that minimal sulfite is better for the stain, but a certain amount is required if the fixer is to be reused. Otherwise it will deteriorate very quickly. For one-shot use, you could leave it out.

    For paper, some sulfite is recommended to preserve the thiosulate. It's harder to detect insufficient fixing with paper.