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  1. #61

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    I've located some 95% ethyl alcohol (food grade). I'm interested in making a stock solution of phenidone in alcohol because I don't have weighing equipment accurate enough to measure the small quantities in which phenidone is usually used.

    Presumably the more concentrated the better the keeping. Does anyone know how soluble phenidone is in alcohol, and how long would a concentrated solution last without noticeable degradation?

  2. #62

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    Sandy,

    Is it possible to mix the working solution and keep it in a beaker for several hours? I only develope one BTZS tube at a time but I have several of them. Could the working solution stay in a beaker for at least 7 hours? Or is it essential to mix just before use each time?
    Francesco

  3. #63

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    Quote Originally Posted by Francesco
    Sandy,

    Is it possible to mix the working solution and keep it in a beaker for several hours? I only develope one BTZS tube at a time but I have several of them. Could the working solution stay in a beaker for at least 7 hours? Or is it essential to mix just before use each time?
    Francesco,

    Frankly I have never tested the concept and the most I have ever delayed before using a mixed working solution is about an hour. However, I think that the color of the solution could be a guide. Once it starts to turn brown oxidation has already set in and your results would be affected. So long as the solution remains very pale amber I suspect that it would be okay.

  4. #64

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    My only experience with Pyro HD extended over a 12 hr period with good results. In between sessions did store in nearly full & capped container.

  5. #65
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    How different is Pyrocat from Dixactol monobath? It is my favorite for MF and I am considering giving Pyrocat a try as an alternative to PMK. I noticed Dixactol seems to have all the advantages of PMK with finer grain and greater highlight clamping. If Pyrocat gives me the same results - It is certainly much cheaper to make and the accutance is every bit as good as the PMK.
    My photos are always without all that distracting color ...

  6. #66

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    Is a very different formulation, Sandy uses catehcol and phenidone, Thorton uses catechol, glycin and phenidone I beleive. Of course the mayor difference is price...I think you will be pleased with Pyrocat HD.

  7. #67

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    Quote Originally Posted by Jorge
    Is a very different formulation, Sandy uses catehcol and phenidone, Thorton uses catechol, glycin and phenidone I beleive. Of course the mayor difference is price...I think you will be pleased with Pyrocat HD.
    I hope to address here the last two message by Frank and Jorge.

    First, for Frank. I have never run any real tests on the DiXactol formula so can not say how it compares to Pyrocat-HD. I develped about 20-30 sheets of 4X5 film in DiXactol a few years ago but not with the air of comparing it to another developer. What I can tell you is that the brownish color stain is very similar to what you get with Pyrocat-HD. I quickly lost interest in DiXactol because it is not energetic enough for my needs, which as you know is primarily alternative printing. Development times to get the needed CI for carbon or kallitype printing would be much too long for my taste with DiXactol.

    Jorge, with regard to the formula. Fact is I don't know exactly what is in DiXactol since it is a proprietary formula and Thornton has not released the ingredients. However, from reading Thornton's recent article in PhotoTechniques I gather that the original DiXactol formula consisted of pyrocatechin and glycin, not phenidone. The last Thornton formula, Exactol, contains pyrocatechin and phenidone, and perhaps also glycin. Note also that Thornton's mixture for the working solution of Exactol is 1:1:100, exactly same as Pyrocat-HD.

    I will add that several years ago I experimented with the addition of glycin in varying amounts to the Pyrocat-HD formula but did not find that anything was gained.

  8. #68

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    I agree Sandy, I have Thorntorn's book the "edge of drakness" and I seem to recall he mentions using glycin, catechol and phenidone, but like you I am guessing.

  9. #69

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    I used Pyrocat-HD for the first time yesterday, using 2+2+100 on 120 size HP5+. Using the graph in Sandy's new documentation I aimed at gamma=.5 for VC paper. I found the results quite contrasty.

    Is there a reason that in the massive amount of info that Sandy has produced and generously presented to us, there is no graph for HP5+ at 100+1+1 dilution? Obviously long development times might be an issue for some people, but an extra 5min would not bother me.

    Also, is there any data for temperature compensation for those of us who are fixated at 20degC? I used the published PMK factors for HP5+ that must be fairly relevant.

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