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Thread: PyroCat HD

  1. #21

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    Michael,
    The developer Pyrocat HD is mixed from individual chemicals that may be purchased from Artcraft or Photographers Formulary. The recipe for this developer may be found on Unblinkingeye.com. It is listed under the heading Formulae. There is also an article on the Unblinkingeye site that was written by Clay Harmon in which he covers testing of this developer with several different films. Hope this is some help to you. Good luck.
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

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  2. #22

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    As to the status of APX: I'd probably be the last one to hear about it. I'm not "in the know" on these kind of things. I've got a good stash of sheets and 120 rolls, tho.

    As to Pyrocat-HD: Read the articles at unblinkingeye.com:
    http://unblinkingeye.com/Articles/Pyrocat/pyrocat.html
    http://unblinkingeye.com/Articles/Pyrocat2...2/pyrocat2.html
    http://unblinkingeye.com/Articles/PC-HD/pc-hd.html

    Pyrocat-HD works great in rotary processors. You do have to mix it yourself, but it's very easy to use. I like it a lot, it's my developer of choice nowadays. No need for a nitrogen burst system or any additives to prevent rapid oxidation and extra fog.
    Nobody ever went broke underestimating the intelligence of the American public.

  3. #23
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    There is a guy in Quebec that sells PyroCat-HD in powder form. Two tubs, 1 for A and 1 for B. I am trying to get the address and prices. Once I have this I will post here. From what I hear it's REALLY cheap.

    I did my 4x5 negs in a Beseler tube on the rotary platform. Seemed to work fine. No scratches and even development.
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  4. #24
    Ole
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    I was just on my way to the darkroom and thought of this...

    A few questions on Pyrocat-HD:

    At 1:1:100, the total concentration of pyrocatechol will be 0.05g/liter, plus 0.0002g Phenidone. This is less than a fifth of the lowest concentration in any other developer formula?

    On unblinkingeye it is said that 100ml water plus 100g Potassium carbonate makes a 100% solution, which is clearly rubbish. Things like this tends to make me sceptical...

    I don't have K2CO3 at the moment, so will have to use the Sodium equivalent. Will this make a significant difference? I intend to add the Na2CO3 to the water, and not bother with a stock solution B.
    -- Ole Tjugen, Luddite Elitist
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  5. #25
    Eric Rose's Avatar
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    I would suggest you email Sandy King directly and see what he says. I'm not a chemist so have no idea about that sort of thing, however the 1:1:100 formulation I used produced very nice negs with HP5.
    www.ericrose.com
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  6. #26
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    Clearly the idea that 100g in 100ml of water constitutes a 100% solution is not correct. There was a raging debate on the B&S forum about a year ago about this, with the people who have never taken chemistry insistent that this would indeed be a 100% solution. Nevertheless, the formula as printed in unblinkingeye.com IS correct in the amounts it calls for. Keep in mind that the catechol is the main developing agent, not the phenidone. All I can say is that this developer blows the socks off of any other staining developer in terms of sharpness, low b+f, and predictability.

    Clay
    I just want to feel nostalgic like I used to.


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  7. #27

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    Ole, I am using potassium hydroxide 10% for the B solution and it works great. The Sodium Carbonate has to be diluted more.

  8. #28
    Ole
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    Jorge, how much of the hydroxde do you use? Same proportions (1:1:100), or more?

    (It probably doesn't matter, as the total OH- activity will be high enough to activate the developer anyway. There is a LOT more alkali than developer in that mix&#33

    BTW; there's a zero too many in my previous post: A liter of developer contains 0.002g phenidone, not 0.0002. Still a very small amount...
    -- Ole Tjugen, Luddite Elitist
    Norway

  9. #29

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    Somewhere in the past I learned that a percent solution is based on the number of grams of a chemical in a given amount of water. Therefore, a 1% potassium carbonate solution is made up of one gram of potassium carbonate in 100ml of water, or 10grams of potassium carbonate in 1000ml of water. Many photograhic texts continue to describe a percent solution in this way.

    From the discussions on this topic last year on the alt-photo-process list I learned that chemists describe the term percent solution in a different way, so that 100g of potassium carbonate in 100ml of water is not exactly a 100% solution. However, I have no practical way of adopting the measuring system of the chemicsts so I will continue to refer to the Pyrocat-B stock as a 100% solution of potassium carbonate.

    It is possible to substitute sodium carbonate for potassium carbonate with Pyrocat-HD. To do so, prepare a 20% stock solution of sodium carbonate, i.e. 20g of sodium carbonate in 100ml of water. To prepare a working solution dilute 1 Part A + 5 Parts B + 100 parts water. This working solution will have working qualities very close to the 1:1:100 dilution made up from a 100% potassium carbonate stock solution.

    Potassium hydroxide will also work as the accelerator but my tests indicate that its use results in slightly larger grain than the carbonates.

    Sandy King

  10. #30

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    Quoting from a previous message,


    "At 1:1:100, the total concentration of pyrocatechol will be 0.05g/liter, plus 0.0002g Phenidone. This is less than a fifth of the lowest concentration in any other developer formula?"

    The very small amount of reducing elements in a liter of working solution is one of the reasons for the outstanding sharpness of the Pyrocat-HD formula. As a rule develolpers with very small amounts of reducing elements tend to give sharper negatives than those with larger amounts. D76 1:1, for example, is visibly sharper than D76 straight.

    Regarding the amount of Phenidone, I see that you corrected in another message the above amount. The amount is still very small, but phenidone is strongly super-additive with pyrocatechin, and it also has strong regenerative qualities. And at the given amount of 0.002g per liter of working solution it plays a very big role in development. Metol, even when substituted in the PyrocatHD formla at 10X the amount of phenidone, impacts develoment less than phenidone.

    Sandy King



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