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Thread: Pyrocat-HD Part A precipitate

  1. #1

    Join Date
    Apr 2015

    Pyrocat-HD Part A precipitate

    Has anyone had a white precipitate form in the Part A of their Photographer's Formulary Pyrocat-HD puchased as a liquid mixed in glycol and if so what did you do about it? I've seen threads about Part B precipitating but not Part A. In those instances the precipitate could be driven back into solution by heating. I first tried vigorous shaking and when that didn't work, I heated the solution by putting the bottle of Pyrocat-HD into a water bath at 130F (54C) which is the temperature of the hot water coming out from my tap.. That didn't work either. Any recommendations? I wasn't sure as to high I could heat the solution without altering it. Could I go to just below boiling or would that render the developer useless? Thanks

  2. #2

    Join Date
    Sep 1998
    Oregon now (formerly Austria)

    Re: Pyrocat-HD Part A precipitate

    I don't use Pyrocat, so I can't help specifically, but common causes of precipitates in such solutions are:

    Not using distilled water. If the solution is close to a saturated one, distilled water is a must, otherwise not all of the reagent will go into solution. If this is the case, the developer may not be as active as expected and can cause underdevelopment. However, if the amount of precipitate is small, filtering may still give you an active enough solution.

    Impurities in the chemicals, which are often insoluble and just precipitate out. In this case, filtering removes them without significantly affecting the activity of the developer.

    Hope this helps,


  3. #3

    Join Date
    Dec 2011
    Sydney, 34 degrees south

    Re: Pyrocat-HD Part A precipitate

    It happened to me quite recently, but with Pyrocat HD in glycol that I made from scratch. There wasn't much of it, and initially it was made up of transparent/whitish particles, which have since turned brown.

    However, they stay on the bottom of the bottle unless disturbed, and the developer works just fine, so I'm ignoring it.

  4. #4

    Join Date
    Aug 2000

    Re: Pyrocat-HD Part A precipitate

    I have never bought a pre-mixed solution, but I have had a few particles precipitate in glycol over the years I have mixed my own PCat HD. It is usually caused by the temperature in the darkroom getting a little lower than usual.
    Ijust decant it and carry-on. No problems,but I can not vouch for what you have purchased.

  5. #5

    Join Date
    Apr 2015

    Re: Pyrocat-HD Part A precipitate

    Thanks everyone. Appreciate the input. I decided to heat the solution to just below boiling. Precipitate disappeared. Now I will develop a few films to make sure I didn't alter anything with the high heat.

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