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  1. #1

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    For those who may want to try a Pyro paper developer, the following is the latest formulation that I have worked with:

    43 gm Sodium Sulfite
    .3 gm Phenidone
    10 gm Catechol
    5 gm Pyrogallol
    50 gm Sodium Carbonate
    3.5 gm Potassium Bromide
    Water to make 1 liter

    Dilute 1-1 to make 2 liter of use solution

    The phenidone should be diluted in alcohol just as in the Pyrocat formula
    As in all cases where exposure to Pyrogallol is involved, eye protection, nitrile gloves, and respirator should be worn. (Just as in any pyro formulation).

    My early tests indicate this is a very active developer that shows good tonal separation throughout the print scale. Paper speeds are typically showing a one stop speed increase. Development times typically 2-3 minutes.

    If you decide to use this, I would appreciate feedback of your experience with this formulation.

  2. #2
    Silverpixels5's Avatar
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    Donald:

    Just a few questions....

    About how many sheets can you get through this before it starts to die? Once it starts to loose effectiveness, have you found that some KBr can make it go a bit longer? What is the shelf life of the working and stock solutions?

    I'm not sure if you'll be able to answer all of the questions, as i'm not sure how long you've been using this developer, but any information you can give would be appreciated. Thanks for all your valuable information that you continue to contribute to this and other forums!
    RL Foley

  3. #3

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    Ron,

    My experience with this developer shows that it loses steam at about 4 hours. It is still active but development times will need to be lengthened to compensate. That is based only on time in a tray...I don't have the number of sheets calculated since I haven't depleted it in that manner.

    The addition of additional KBR will not extend life in this case.

    This should be mixed immediately prior to use...once the chemicals are in combined state they will begin to oxidize. If one has accurate enough scales then the formula recipe can be cut in half for one liter of use solution.

    If one wishes to mix stock solutions then this will need to be a multi part stock like the ABC formula. The developer agents and bromide in one part, the sulfite in the second part, and the carbonate in the third part. If I were to do this then I would calculate this out to arrive at the amounts of stock to add to arrive at use dilution. I haven't done that myself and thus have not made the calculations.

    Sounds like something for me to work on.

  4. #4
    Silverpixels5's Avatar
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    thanks for the info! Now i have a way to use up all the leftover pyro I have from not using ABC as much anymore. :-)
    RL Foley

  5. #5
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    You can make the first part of your 3 part developer in propylene glycol. It will keep indefinitely. You will have to heat the glycol mix in order to dissolve it. Put it in the microwave in a pyrex container and bring the temperature up to about 150 F. I'm not really crazy, just a little off center.
    Gadget Gainer

  6. #6
    Jorge Oliveira's Avatar
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    I'm not really crazy, just a little off center.
    Patrick

    Now I understand!

    But I fully agree with the PG suggestion.

    Jorge O
    Curitiba - nice place to live, if you don't care about the weather...

  7. #7

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    Donald, thank you for publishing this formulation. I am going to split the formula into "A" and "B" solutions. This will be easy for me to do, since I already have percentage solutions of the incorporated reducing agents dissolved in ethylene glycol.

    "A" solution

    70ml (Dry) Methanol
    .3 gm Phenidone
    10 gm Catechol
    5 gm Pyrogallol
    dissolve all in methanol, then add
    Ethylene or Propylene Glycol to 200ml

    "B" solution

    150ml boiled distilled or deionized water at 52 deg. C
    43 gm Sodium Sulfite
    50 gm Sodium Carbonate
    3.5 gm Potassium Bromide
    water to 200ml

    These two solutions should each have a very long shelf life.

    Tray life? We'll see. I will probably use this as a on-shot.

    Have you tried Benzotriazole instead of KBr?
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  8. #8

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    Thank you all for your input. If you decide to try this please let me know your experience. I have not tried Benzotriazole in the formula.

  9. #9
    Jorge Oliveira's Avatar
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    Tom

    Your metanol-glycol combination is very attractive - easier to mix.
    But my personal experience with stock solutions containing sulfite is that they will oxidize within a couple of months.
    With my standard PA dev (using Pglycol), I add a spoon of sulfite at dev time, because the borax/sulfite stock was 'wearing out'.

    Jorge O
    Curitiba - nice place to live, if you don't care about the weather...

  10. #10

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    I agree, Jorge.
    My inclination is that is best to add the sulfite - if it is needed - when you mix the working developer. A possible alternative would be to buffer it with some bisulfite.
    Tom Hoskinson
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