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  1. #1

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    Pyrocat-HD Solution B

    I have been using Pyrocat-HD for some time now, and mixed up the last batch using Propylene Glycol for Solution A. Great results. Am now trying to mix up 100 mls Solution B, but can't get the Potassium Carbonate to completely dissolve. After 2 attempts I need some help .

    I added the carbonate very slowly and stirred like crazy, with no success. On Unblinking Eye, I notice that Ted Kaufman uses a 10% solution of Sodium Hydroxide for Solution B. Any experience with this?

    Using 120 roll film and 35mm. No sheet film.

    Thanks in advance,
    Lyn Arnold

  2. #2

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    Hi Lynn, I've reduced the concentration of solution B slightly, 70g of potassium carbonate to 100ml of distilled/deionised water. I find this also prevents any crystalisation on storage particularly when there's a drop in temperature.

    Seems to work just fine. I've had no noticable change in negative density etc.

    For ease of mixing I use a heated magnetic stirrer which greatly and efficiently speeds up the mixing process.

  3. #3
    Ross Chambers's Avatar
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    This probably won't help, and Sandy usually seems to detect Pyrocat post and comes up with an answer, but I did not have a problem. My final quantity was 500ml, not 100, perhaps that makes a difference?

    Quantities:
    Distilled water @ 20 degrees C 375 ml
    Potassium Carbonate 375 gm
    Mix
    Add Distilled water @ 20 degrees C to make 500 ml.

    It seems not excessive to make up a half litre of A and B, they have lasted for me for approximately 6 months in 3 x 200ml bottles from the pharmacy.
    Regards - Ross

  4. #4

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    Are you sure that you have potassium carbonate and not sodium carbonate? If you use the right amount of potassium carbonate and water and add the carbonate slowly with stirring it should go into solution easily. If it does not I would suspect something wrong with the chemical.

    But yes, you can use other accelerators, including a 10% solution of either sodium hydroxide or potassium hydroxide, but this may give slightly larger grain. You can also mix a 15% sodium carbonate solution and use 5X the amount of B solution. That is, the 1:1:100 dilution becomes 1:5:100.

    Sandy



    Quote Originally Posted by Lyn Arnold View Post
    I have been using Pyrocat-HD for some time now, and mixed up the last batch using Propylene Glycol for Solution A. Great results. Am now trying to mix up 100 mls Solution B, but can't get the Potassium Carbonate to completely dissolve. After 2 attempts I need some help .

    I added the carbonate very slowly and stirred like crazy, with no success. On Unblinking Eye, I notice that Ted Kaufman uses a 10% solution of Sodium Hydroxide for Solution B. Any experience with this?

    Using 120 roll film and 35mm. No sheet film.

    Thanks in advance,
    Lyn Arnold

  5. #5

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    Thank you Trevor, Ross and Sandy for your quick response and your suggestions. I know the chemical is potassium carbonate, and I have used the same jar for previous batches. Will try making up 500mls, and if that is a failure I'll order some more chemical. But might test the sodium hydroxide for selected film/subject.

    Lyn Arnold

  6. #6

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    Well...mixed up 500mls, taking over 30 minutes but with the chemical going into solution, albeit a cloudy one. And I needed very little top up of distilled water to make up to 500mls. Checked the solution an hour later and there is no apparent sediment.

    So once again thank you all and three cheers for APUG!

    Lyn Arnold

  7. #7
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    A mixture of borax and hydroxide can be made to have the initial pH of the standard Pyrocat B solution. I have found such a solution to work quite well. You can also start with a metaborate (Kodalk) solution and add enough sodium or potassium hydroxide to get the pH you want. I posted the details once IIRC, but don't remember them. When I run out, I'll have to do the experiment all over.
    Gadget Gainer

  8. #8

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    Pat,

    Save your notes the next time and post them here!!

    Sandy


    Quote Originally Posted by gainer View Post
    A mixture of borax and hydroxide can be made to have the initial pH of the standard Pyrocat B solution. I have found such a solution to work quite well. You can also start with a metaborate (Kodalk) solution and add enough sodium or potassium hydroxide to get the pH you want. I posted the details once IIRC, but don't remember them. When I run out, I'll have to do the experiment all over.

  9. #9
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    I used to think I was getting old. I don't have to think that anymore. I have arrived.
    Gadget Gainer

  10. #10
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    I just escaped from the dungeon of the photographic demon. I found that the following are reasonable substitutes for the standard Pyrocat B solution:

    1) 100 grams Kodalk (sodium metaborate) + 30 grams potassium hydroxide or 21.4 grams sodium hydroxide + water to make 1 liter.
    2) 69 grams borax + 50 grams KOH or 36 grams NaOH + water to make 1 liter.
    Gadget Gainer

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