Dilutions and Pyrocat HD

Discussion in 'B&W: Film, Paper, Chemistry' started by jtsatterlee, Jan 3, 2005.

  1. jtsatterlee

    jtsatterlee Member

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    Could someone explain what changing the dilution ratios in Pyrocat HD does, ie 1:1:100, 2:2:100, etc?

    What properties does sol A, and Sol B carry, how do they interact, what is the imapct of changig the ratios, is there a good rule of thumb for knowing how to change the ratios and what impact does the change have on the resulting negative and processing time.
     
  2. sanking

    sanking Member

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    Have a look at my response in the thread "Pyrocat and flat scenes." I think it addresses part of your question.

    As for the other part of your question, Part A contains the reducing agents and sulfite, Part B the carbonate accelerator. You choose dilution for the contrast required for a development time of 10-12 minutes. For graded silver papers a 1:1:100 dilution will develop a FP4+ negative to the right CI in about 10 minutes. For VC papers or AZO #2 or palladium try the 2:2:100 dilution with about the same time of development. Low contrast films need about 30% more development time to reach the same CI.

    For extremely flat scenes with low contrast films that require development times over 12 minutes I recommend an asymmetrical mixture of A and B, say 3:2:100 or 4:3:100. The extra amount of A helps to keep B+F low.

    Sandy
     
  3. Tom Stanworth

    Tom Stanworth Member

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    Sandy,

    Does the asymmetric mix make a big differnce to B+F? I have tried my first few sheets of Efke 100 in pyrocat:

    Used a paterson orbital (quick, easy etc), 20 degrees C, 13 mins with 1:1:100 - needed G4.5 on VC (colour diffuser head)
    As above, but 1.5:1.5:100, 15 mins - Yet to be printed but looking pretty close for G2.5-3.

    Do my times seem very long to you (bearing in mind I am trying to get it right for G2.5-3 on VC and at 20 degrees ? I use a colour Devere head.

    I notice that B+F is nowhere near as high as Dixactol, but still a bit higher than I would like, but would an asymetric mix make much difference. Perhaps a 3:2:100 would reduce dev times and B+F? This further reduction in time would really help, esp if I wish to use partial agitation in trays which I would imagine would require a good 50% increase in time over the orbital?

    Perhaps I should use a higher temperature, its just that I would prefer to use something lower as my darkroom temperature is erratic and if I go for 24 degrees or so, variations in ambient are likely to cause bigger variations in the cooling of the dev during development....maybe,,,,,maybe flawed logic.

    Tom
     
  4. noseoil

    noseoil Member

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    Tom, one thing you may want to change, which does not deal with concentration or temperature, is agitation. Pyrocat does not have the large issue of irregular staining of negatives that PMK does, one large plus with Pyrocat as a developer. You can run into trouble when stagnation starts running into minutes and uneven stains appear in clear blue skies, but typically this shows up in terms of 2 or more minutes without agitation.

    What agitation cycles are you using now? This can make a huge difference with Pyrocat's development times and activity level. I have recently started using tube development and times have become much shorter, due to the constant nature of development, when compared to trays and intermittent agitation.
     
  5. Tom Stanworth

    Tom Stanworth Member

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    with the post above I have used a paterson robital which has continuous agitation.

    I have used 20 degs C in all cases.

    I have also used the dev with 2min intervals in a small tank for 120 for 13 mins at 1:1:100 (needed grade 3.5 VC) and in a combitank with same film in 5x4 (same details), also needing grade 3.5 plus.

    I was surprised that even at 13 mins at 1:1:100 and constant agitation in the orbital , that efke 100 was still flat. 15 mins at 1.5:1.5:100 looks much better.

    I daresay I'll get thing right in the end. (my first attempt with the dev seemed good with Tmax100 with agitation once per minute for 14-15 mins at 1:1:100). I deally I would like to be around the 10 minute mark, hence me trying more concntrated soups, tho I may try higher temps too. I reckon at 24 degs and 1.5:1.5:100 I should be about there.............maybe.
     
  6. sanking

    sanking Member

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    Tmax-100, for a given dilution and time of develoment, is a much more contrasty film than Efke PL 100, which would explain why your first attempts with it came out well. But for reasonable development times with Efke PL 100 you might be better off with the 2:2:100 dilution, or 3:2:100. In general B+F does not matter nearly as much with silver gelatin printing as with alterantive processes so I belive the symmetrical use of parts A and B should be fine.

    Sandy
     
  7. Tom Stanworth

    Tom Stanworth Member

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    Tks Sandy, you are a star. I noticed efke to be quite low in contrast relatively, when I used it ages ago with HC110. However, as my dev times escalated with pyrocat HD, I was concerned it was becoming a concern (problem with my homebrewing crossed my mind).

    The latest is that Efke 100, 1.5:1.5:100 at 20 degs C, Paterson orbital continuous agitation, 15 mins produce a straight reporoduction of the scene on G3.5VC, with G2 graded being about 1/2 grade too flat. Very close......now for 2:2:100 and perhaps 22 degs...........should cut time quite a bit.
     
  8. Claude

    Claude Member

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    Tom,
    I'm using Efke PL100 with pyrocat (rated 64iso) diluted 2:2:100 10 minutes at 24°C. I get beautiful details in shadow areas.
    Claude
     
  9. Tom Stanworth

    Tom Stanworth Member

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    Sounds like my results are about the same, considering my lower temperature and soncentration?

    What methyod of agitation do you use though?

    Tom
     
  10. Claude

    Claude Member

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    I allways use a Jobo CPP2 processor, with the lowest speed available.

    Claude