Pyrocat: Versions and Mixing Directions

Pyrocat: Versions and Mixing Directions

  1. sanking

    sanking Member

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    sanking submitted a new resource:

    Pyrocat: Versions and Mixing Directions - Pyrocat: Versions and Mixing Directions

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    Last edited by a moderator: Feb 6, 2016
  2. Jim Noel

    Jim Noel Member

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    Thanks for the update.
    Jim
     
  3. Lee L

    Lee L Member

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    Sandy,

    Thanks very much for taking the time to post this in one place.

    Lee
     
  4. Jeremy

    Jeremy Member

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    Can we make this an article or "sticky" post? Thanks for putting this all in one place, Sandy.
     
  5. mikebarger

    mikebarger Subscriber

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    It is in the articles section under staining developers
     
  6. john_s

    john_s Subscriber

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    Sandy, there's an error "dichromate" should be Carbonate.
     
  7. sanking

    sanking Member

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    Thanks. I corrected it.

    As a carbon transfer printer I have dichromate on the brain.

    Sandy
     
  8. john_s

    john_s Subscriber

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    I had never before seen the alternative mixing directions for Pyrocat-MC (without a little water). Is the list of ingredients just those in the list under the heading "Stock A" or should one use some TEA as well?

    Could that amount of heat (250degF=120degC) do some damage to any ingredient? I have mixed some formulas at lower temperature than recommended by allowing lots of time for dissolution (a week in the boot/trunk of the car on long trips). Would this be worth a try for this formula?
     
  9. sanking

    sanking Member

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    This is the first time the alternative method has ever been suggested. Pat Gainer tried it a few days ago and said that it worked, so I decided to recommend it. The high temperature will not damage any of the ingredients so far as I know. I have mixed pyrocatechin, metol and ascorbic acid before at this temperature and there was no problem. You don't need any TEA or water mixing this way.

    I suspect that you could mix at a lower temperature with a hot plate stirrer but have not actually done so. Pyrocatechin and ascorbic will definitely go into solution at a much lower temperature, not sure about the metol.

    Sandy
     
  10. gainer

    gainer Subscriber

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    I think my report to Sandy was a little garbled or something. My experiment used a 100 ml of glycerol (also callsed glycerin) to hold the Metol and ascorbic acid. Heat it to 250 but no higher than 300 F.This heating drives the water form the hygroscopic glycerol. Now add 4 grams of ascorbic acid, stir it well and add 2.5 grams of metol. The result should be a clear yellow-orange soultion which will remain clear as it cools. Now add 50 grams of catechol and enough propylene glycol to make a liter. Heating helps dissolve the catechol, and it won't hurt to make it hot enough to boil off any water that might be in the glycol. The stock solution becomes considerably redder when the catechol is added.

    You may find other uses for the glycerol solution of Metol and ascorbic acid. I made a double batch just so I'd have some to play with. I used the extra to make a water based Pyrocat MC stock just to see how long it would last. I'll tell you a year from now how it faired. Its pH is about 3, which should help it keep a while.

    I don't think the glycerol mix is a simple solution. For one thing, only 1 gram of Metol should have remained dissolved on cooling. I have my own ideas about what chemical reactions may be going on between the H2SO4 of the Metol and the glycerol at 250 F but I rely more on pracrice than on theory, especially if there are two or more theoretical explanations.
     
  11. Bruce Osgood

    Bruce Osgood Membership Council Council

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    THANK YOU SANDY!

    And Patrick, thank you as well. This is a big undertaking and I really appreciate your work and finally bringing all the posts and updates to one (two, counting Gadgets) page.

    I really appreciate it.
     
  12. sanking

    sanking Member

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    Last edited by a moderator: Jul 19, 2009
  13. wildbillbugman

    wildbillbugman Member

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    Thanks Sandy,
    The two-part developer method is something I had not read about HD. I wonder if varriatios in time and/or concentrations would yield any usefull variations in contrast,etc.
    Bill
     
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  15. gainer

    gainer Subscriber

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    Illustrating Pyrocat MC.

    These photos show why I like Pyrocat MC. They are on 35 mm film. The detail is shown in the spine of a book on the shelf between the easy chair and the snow dog portrait. I used 1:1:50, 8 minutes for the FP4+ and 9 minutes for the Arista EDU 400 Supreme at 73 F. The Arista was slightly overdone.
     

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  16. gainer

    gainer Subscriber

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    I forgot to mention that these photos were scanned from 8x10 prints of most of the negative. The overviews were digitally reduced. The details were scanned at high resolution from small portions of the photo print about a centimeter wide, which makes them about a millimeter wide on the negative. I used no sulfite anywhere along the processing line.
     
  17. sanking

    sanking Member

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    Yes, changing the time and/or concentrations will give useful variations. Here is what I posted in another thread about that.

    1. I would recommend that you simplify matters by not changing the time in either Solution A or Solution B. But if you change the time stick with it as it will simplify the other adjustment you can make.

    2. Contrast is controlled by the amount of reducer that can be absorbed by the emulsion in Solution A. Assuming you stay with 6 minutes and 75F, using a stronger dilution will increase final negative contrast, using a weaker one will reduce final negative contrast. In other words, if 1:20 is the norm, a 1:10 dilution will give you more contrasty negatives, a 1:40 dilution will give negatives with less contrast. I think 1:10 is a good starting point for tank development with intermitten agitation, 1:20 is for rotary agitation.

    3. Effective film speed is controlled by the time in solution B. What happens is that the reducer in the emulsion is quickly used up in the highlight areas, and since it can not be replenished as in normal single bath processing, the negative builds contrast rapdily when it goes into the solution, but in about three minutes all of the reducer is used up so that the build up of density in the highlights stops. However, the negative will continue to build up density in the mid-tones shadows throughout development, which increases effective film speed. So if six minutes is the norm for Solution B, four minutes will give less effective film speed, ten minutes will give more effective film speed.

    Sandy King
     
  18. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    For the divided option, how long is the recommended bath in solution B?

    Very interesting read, Sandy. Thanks for posting.
     
  19. sanking

    sanking Member

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    Hi Thomas,

    I have been using six minutes in both Solution A and Solution B at 75F with the 1:10 dilution for Fuji Acros, rating the film at EI of 50. Less time in B will reduce film speed slightly, more time will increase it slightly, but I think six minutes should be about right for most films.

    Sandy
     
  20. Peter De Smidt

    Peter De Smidt Member

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    Sandy,

    Do you recommend the same development scheme for TMX 100 as you do for Acros? (I.e. two bath, six minutes each in A and B, 1:10 dilution at 75F?)
     
  21. sanking

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    Peter,

    With normal processing Fuji Acros tends to take a bit longer to reach the same contrast than TMax-100 so I might suggest you develop the Tmax less, say 5+5 at the same temperature and dilution.

    Sandy
     
  22. Peter De Smidt

    Peter De Smidt Member

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    Thanks Sandy. I'll give it a try.
     
  23. Mahler_one

    Mahler_one Member

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    Sandy: Where can one purchase the Pyrocatechin? I did not see it at Art Craft or Formulary.

    Ed
     
  24. Mahler_one

    Mahler_one Member

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    Sorry....did not know the name was Catechol...obviously available at PF and others. My mistake.
     
  25. Mahler_one

    Mahler_one Member

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    Sandy: I reviewed your instructions for mixing Pyrocat HD, and I noted the 50 degree F suggestions for part A. How important is that temperature, i.e., it can be hard to get temperatures that low in certain areas of the country.

    Ed
     
  26. PhotoJim

    PhotoJim Member

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    50 C sounds more likely. That's a fairly standard developer mixing temperature.