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Thread: Pyrocat question...

  1. #1
    Christopher Barrett's Avatar
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    Pyrocat question...

    I'm new to Pyro and am using PyrocatMC in my Jobo with Fuji Acros. Though I'm really pleased with the feel of my negs, I had to drop my speed considerably. Acros runs pretty true to 100 in XTol but feels more like 25 in my Pyro routine. I'm doing 1:1:100 for 10 minutes at 20°C. I just did a speed test, lighting a grey card with strobe. My Zone I neg at ISO 32 returned a density of .05 over B+F, which is still thin, so an ISO of 25 seems closer to true for me. My Zone I to Zone VIII showed a density diff of 1.07, so I'm gonna bump my dev time up 25% and go again.

    Thoughts? Advice?

    Thanks!
    -CB

  2. #2

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    Re: Pyrocat question...

    I haven't used a pyro developer in years, but it sounds like you know what you are doing and are on the right track.

    There are two "pyros" out there and both are developing agents with similar chemical structures:

    -- Pyro, AKA Pyrogallic acid, Pyrogallol

    -- Pyrocatechin, AKA Catechol, Pyrocatechol, ortho-dihydroxybenzene

    I've only used the later and don't know the differences in effects. Perhaps other do. But be careful, at least the latter is a severe irritant -- probably th former as well.

    FYI, if anyone on this board wants an ounce of the latter, I can send it to you for the price of shipping.

  3. #3

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    Re: Pyrocat question...

    I've used Pyrocat-HD for many years to develop several different films and fairly recently started experimenting with -MC and I've never measured that much loss in film speed. Is the stock developer fresh? Are you running the Jobo at its slowest speed?

  4. #4

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    Re: Pyrocat question...

    I haven't done any densitometry, nor do I use Acros, but I'm very surprised at the apparent 2 stop speed drop. I use pyrocat hd quite a lot and have never noticed a speed drop compared to box speed with the films I have used with pyrocat so far. Since the mc and hd variants should respond quite similar and pyrocat isn't noted for a large speed drop, I suspect something odd is going on here.

  5. #5
    David Schaller
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    Re: Pyrocat question...

    I use Pyrocat HD with trays or hand inversion, and I get Acros @80, just as I do with D-76. I do develop at 70F though. I use the 1:1:100 Pyrocat hd in glycol from PF.

  6. #6
    alanbutler57's Avatar
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    Re: Pyrocat question...

    I've run into this before with HD and suspect I'm just not using enough solution.

    Somewhere I read Sandy King; who developed Pyro HD, recommends 75ml of 1:1:100 per 4x5 neg, but I've always used 600 ml in my Jobo to develop 12 images at a time, and usually had to "push" in the scanner.

    When I recently started playing with double sided X-ray film I cut back to 4 negatives per run and both green (ISO 100) and blue (ISO 50) look about right for the exposure. Just a visual observation combined with reading the histogram on the scanner.

  7. #7
    Christopher Barrett's Avatar
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    Re: Pyrocat question...

    Hmm, maybe I'll contact the Formulary and see what they think. I like the look of the Pyro Negs but a two stop speed drop is craziness.

  8. #8

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    Re: Pyrocat question...

    I suspect you don't have enough active developer for the area of film being developed. It's been a while, but I believe I ran into this when I first started using pyrocat. I use 2+2+100, and I think it was so I could do 12 sheets in a jobo 3010 drum without exceeding the drum capacity.

  9. #9

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    Re: Pyrocat question...

    Quote Originally Posted by Christopher Barrett View Post
    Hmm, maybe I'll contact the Formulary and see what they think. I like the look of the Pyro Negs but a two stop speed drop is craziness.
    You definitely should not see a two stop drop in speed with Pyrocat-MC, though there may be a slight loss in effective film speed compared to Xtol. Many of my tests also indicate that Pyrocat-HD gives just a tad more film speed than -MC, due to the phenidone, but the gain is quite small.

    You should use at least 75 ml per sheet of 4X5 film, using the 1+1+100 dilution. My own tests for film speed were made with this dilution developing in BTZS tubes. With Jobo there is also a minimum amount that must be used depending on the drum. I don't use Jobo so don't know the total volume you need for your system, but more is always safer than less as it assures that all of the film is completely wet out during the first few seconds of agitation.

    I would suggest increasing time of development by about 25-50%, and using more total solution. If this does not solve the problem, try the 2+2+100 dilution, there will be very little difference acutance compared to 1+1+100, but a fairly big bump in CI for the same time of development.

    Sandy
    For discussion and information about carbon transfer please visit the carbon group at groups.io
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  10. #10
    Kirk Gittings's Avatar
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    Re: Pyrocat question...

    Sandy, On a side note....
    As my BTZS 4x5 cap only holds 60ml of solution rather than 75ml, I use a dilution of 1.25:1.25:100. My math suggests this provides the same amount chemical activity and does result in proper highlight densities for my purposes.
    Last edited by Kirk Gittings; 15-May-2017 at 11:15.
    Thanks,
    Kirk

    at age 73:
    "The woods are lovely, dark and deep,
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    And miles to go before I sleep,
    And miles to go before I sleep"

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