TMY-2 in Pyrocat-MC Mystery

Discussion in 'B&W: Film, Paper, Chemistry' started by wessellsp, Jul 21, 2011.

  1. wessellsp

    wessellsp Member

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    I am having a problem on which the chemistry sleuths out there may be able to shed some light. I have been running BTZS tests on FP4+ and TMY-2 in Pyrocat-HD and MC using both constant agitation (in BTZS tubes) and extended minimal agitation (vertical in tubes) techniques, both at 68F. I am reading the densities with the blue and UV lenses of Gretag Macbeth D200-II for use with Azo and Pt/Pd. With the FP4+ I am getting results that correspond with what others have reported, except that the MC B+F is slightly higher. With TMY-2 I am getting terrific results with HD using EMA. The results so far with the MC is another story. The first run EMA negs in my homebrew MC were thin for the short time (20 min.) and thin and seriously fogged and uneven for the 40 min. time. I have a PF bottle of MC, so as a control I ran a test using that - same result. Thinking that my homebrew and the PF MC might have gone off, I mixed a fresh batch of homebrew (heating the glycol to 250F) - same outcome. Thinking that something might be going on at the 250F mixing temp, I next made a batch using the lower temperature method. I haven't done an EMA test with that batch, but a constant rotation test of one sheet of TMY-2 at 15 min. gave me B+F of .15 (blue) and .43 (UV) which seems high to me. BTW, the HD I am using is also homebrew. Since both the HD and MC were made with the same catechol, that shouldn't be the problem. Since the MC is working OK with the FP4+ (except for the slight elevation of B+F vs. the HD) it seems that the metol is OK. Could the ascorbic acid be bad? That's the only thing I can think of.
     
  2. jordanstarr

    jordanstarr Member

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    In the home brews, the catechol doesn't do the developing, just the staining. Is this the first time you've used Pyrocat MC? I know the formulas are similar, but regardless it sounds like a chemical problem. Worst case scenario, stick to the HD formula that appears to work much better.
     
  3. Ian Grant

    Ian Grant Subscriber

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    The Pyrocatechin does act as a developer in both Pyrocat HD & MC. If it didn't there would be no staining.

    Ian
     
  4. Gerald C Koch

    Gerald C Koch Member

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    It is a bad idea to heat the glycol too much. What I do is to add the ingredients to room temperature gycol and then warm the mixture with stirring until the solids dissolve.
     
  5. wessellsp

    wessellsp Member

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    Well, I made up a new batch of MC following Jerry's method. I never let the solution get above 120F. Same outcome with TMY-2 - high B+F for the constant agitation test and fog for the EMA test. BTW, I mixed a batch of Pyrocat-M and used it in a constant agitation test, which resulted in very clean negatives. This implies that the metol I am using is OK and seems to isolate the ascorbic acid as the problem, but who knows?
     
  6. Gerald C Koch

    Gerald C Koch Member

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    I have never tried the this version because you have to add water to dissolve the metol. I believe that this compromises the keeping quality of the concentrate. I prefer to use phenidone or Dimezone S.

    High fog levels could be from some contaminate or the developer being more active than it should be. Are all the chemicals pure or photograde"
     
  7. wessellsp

    wessellsp Member

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    All of the chemicals were purchased from Artcraft and are fresh. I don't have any reason think that there is a problem there, especially since I have obtained good results with the main ingredients (from the same jars) in other developers - the catechol in Pyrocat-HD and the metol in Pyrocat-M. One thing not mentioned previously is that the spent MC from the TMY-2 development is consistently a very deep lavender color. I didn't get that with the TMY-2 in either the HD or M.

    I'm ready to move on from this developer, chalking this one up to the vagaries of chemistry. Since I have obtained good results with both FP4+ and TMY-2 in Pyrocat-HD, I think I will stick with that developer for now. Thanks for everyone's input.