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  1. #1
    climbabout's Avatar
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    pyrocat hd question for Sandy King, Bud at Formulary?

    Related to the recent pyrocat thread, I did not want to hijack it so I started this thread. I've been using Pyrocat HD from the formulary - the A and B solution mixed in water and I'm going to get my next batch from them in Glycol. I generally use a 1.5A/1.0B/175 h2o mixture, so I have quite a bit of the B left over when I run out of A. Can I use the A in Glycol and mix it with the leftover B that's in water? or should I dump the B that I have?
    Tim

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    I think I would dump B. I read that the water based solutions have a much shorter life than the glycol based solutions.

    Fred

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    Tim;
    Please reread my response to Fred in his thread about the Pyrocat MC.

    I cannot give a blanket statement that yes or no this is or isn't OK.

    I can't recomend that you mix a new solution with an older solution. The prudent thing is to use the proper A solution with the proper B solution.
    One of the advantages of Sandy King's formulations are the abiltiy to change dilution ratios, but this creates the disadvantage of having one of the solutions left over from an unbalanced ratio. Kind of a good news bad news thing.
    Just give it some thought, and weigh the pro and con. Is it worth saving a few cents worth of B solution and put a few dollars worth of film into it?

    I think we might call that stepping over dollars and picking up dimes.

    Bud Wilson
    Photographers Formulary
    Celebrating our 30th year

  4. #4
    climbabout's Avatar
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    THANKS

    Quote Originally Posted by Formulary/Bud Wilson View Post
    Tim;
    Please reread my response to Fred in his thread about the Pyrocat MC.

    I cannot give a blanket statement that yes or no this is or isn't OK.

    I can't recomend that you mix a new solution with an older solution. The prudent thing is to use the proper A solution with the proper B solution.
    One of the advantages of Sandy King's formulations are the abiltiy to change dilution ratios, but this creates the disadvantage of having one of the solutions left over from an unbalanced ratio. Kind of a good news bad news thing.
    Just give it some thought, and weigh the pro and con. Is it worth saving a few cents worth of B solution and put a few dollars worth of film into it?

    I think we might call that stepping over dollars and picking up dimes.

    Bud Wilson
    Photographers Formulary
    Celebrating our 30th year
    Bud - thanks for the reply - that's why I asked - when the A is gone, I'll replace both bottles with Glycol.
    Tim

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    Quote Originally Posted by climbabout View Post
    Related to the recent pyrocat thread, I did not want to hijack it so I started this thread. I've been using Pyrocat HD from the formulary - the A and B solution mixed in water and I'm going to get my next batch from them in Glycol. I generally use a 1.5A/1.0B/175 h2o mixture, so I have quite a bit of the B left over when I run out of A. Can I use the A in Glycol and mix it with the leftover B that's in water? or should I dump the B that I have?
    Tim
    Tim,

    I would have to say that it depends a lot on the age of the Stock B solution. Stock B is a straight 75% potassium carboinate solution that I mix in water, even when mixing Stock A in glycol. The reason is that the strong carbonate solution is very long lived. How long I really don't know, but at least a couple of years. It is really only the Stock A solution that benfits in terms of shelf life from mixing in glycol. In fact, I never even considered if the carbonate would go into glycol since it is already so stable in water.

    Maybe Pat Gainer will notice this thread and comment. He is really the brain behind the mixture of both Pyrocat-HD and -MC in glycol.

    Sandyd King
    Last edited by sanking; 05-09-2008 at 08:58 PM. Click to view previous post history.

  6. #6

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    Quote Originally Posted by sanking View Post
    Tim,

    I would have to say that it depends a lot on the age of the Stock B solution. Stock B is a straight 75% potassium carboinate solution that I mix in water, even when mixing Stock A in glycol. The reason is that the strong carbonate solution is very long lived. How long I really don't know, but at least a couple of years. It is really only the Stock A solution that enfits in terms of shelf life from mixing in glycol. In fact, I never even considered if the carbonate would go into glycol since it is already so stable in water.

    Maybe Pat Gainer will notice this thread and comment. He is really the brain behind the mixture of both Pyrocat-HD and -MC in glycol.

    Sandyd King
    Sodium and Potassium carbonates are not soluble in glycol. Both are readily soluble in water.

    I mix my own Pyrocat MC and HD from scratch:

    I use Propylene Glycol as the "A" solution solvent (keeps for years: 3+ and counting).

    I use DI Water as the "B" solution solvent (keeps for 2+ years).


    However, in principle, you could use TEA (Triethanolamine) as an organic source of the alkali.

    This would require testing.
    Tom Hoskinson
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  7. #7
    tony lockerbie's Avatar
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    Sorry, but I'm going to hi-jack this thread a little! I mix my part A in water, what is the life span of this in a partly filled brown glass bottle?
    So far I have had it mixed for around 4 months and pretty much develop everything in Pyrocat HD these days.
    Tony

  8. #8
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    I kept Pyrocat HD mixed in water for about 9-months before using it up. I'd say 9-12 months is about the outer limit.

    As for B - I computed how much dry sodium carbonate to mix with the working strength developer so I don't actually mix a B solution at all.
    juan

  9. #9
    Eric Rose's Avatar
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    Quote Originally Posted by tony lockerbie View Post
    Sorry, but I'm going to hi-jack this thread a little! I mix my part A in water, what is the life span of this in a partly filled brown glass bottle?
    So far I have had it mixed for around 4 months and pretty much develop everything in Pyrocat HD these days.
    Tony
    I had some that was over 2 years old that worked just fine. YMMV.
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  10. #10

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    Quote Originally Posted by juan View Post
    I kept Pyrocat HD mixed in water for about 9-months before using it up. I'd say 9-12 months is about the outer limit.

    As for B - I computed how much dry sodium carbonate to mix with the working strength developer so I don't actually mix a B solution at all.
    juan
    For practical work with partially full Stock A I agree with Juan. 9-12 months is a good limit for Pyrocat mixed in water. When I worked with Pyrocat mixed in water I would always add marbles to minimize oxidation. This allowed the original control solution that I mixed to be effective up to about 1.5 years, and would probably have been good for longer but I used it all up.



    Sandy King
    Last edited by sanking; 05-09-2008 at 06:05 PM. Click to view previous post history.

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