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  1. #11

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    Quote Originally Posted by Tom Hoskinson
    I mix my Pyrocat-HD "A" solution in polyethylene glycol (PEG) and leave the KBr and sodium metabisulfite out. I just assumed these two components would be difficult to dissolve in PEG. BTW, the pyrocatechcol and phenidone dissolve in the PEG at temperatures between 140F and 160F.

    When I started mixing the A solution this way I then added the KBr (as a percentage solution) and sodium metabisulfite when I mixed the working developer. I have made tests with the films I am using with and without the KBr and sodium metabisulfite, and I can not see (or measure) any difference in the results.
    First, I have not had any problem getting the potassium bormide and sodium metabisulfite to go into solution in glycol, though it does involve heating the glycol to around 250º F. But at this temperature both go intoi solution quite easily.

    Tom is basically right in that the omission of potassium bromide and sodium metabisulfite does not make a lot of difference and may not be immediately apparent in your negatives. However, if you specifically test for it by running BTZS types testing in which test films are developed for different periods of time, and the results then read with a densitometer and plotted, you will indeed find some differences. The difference will probably not be evident with shorter development times but with the longer development times one would see with N+ development or with development for alternative printing the difference is quite obvious. In these cases the lack of potassium bromide results in slightly higher B+F levels and the lack of metabisulfite results in slightly more stain. This may not be important if you are using the 1:1:100 dilution and developing only for regular silver gelatin printing, but it definitely matters with the long development times we often need for alternative printing, where any differnce at all in the stain becomes very important because of the highly actinic nature of brown stain.

    I am currently working on some refinements of the Pyrocat-HD formula involving non-symmetrical mixtures of Solution A and B to make it more active for alternative printing and my current thinking is that the best place for the potassium bromide is in the Stock B solution rather than in the Stock A. So the next time I mix a new batch of Pyrocat-HD I plan to try to mix the bromide in with the Stock B, assuming it be soluble with the carbonate solution?

    As for the sodium metabisulfite I plan to continue to put it in the Stock A solution. Although it is not needed as a preservative in this solution, it nevertheless continue to have some impact on negative stain because it releases as sulfite when mixed with water and the sulfite, in even minute quantities, has an impact on total stain, especially evident with long development times.

    Sandy

  2. #12
    roteague's Avatar
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    Is is possible to purchase Pyrocat-HD in powder form? I have neither the time, nor inclination to mix chemicals myself.
    Robert M. Teague
    www.visionlandscapes.com
    www.apug.org/forums/portfolios.php?u=2235

    "A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; a man who works with his hands and his brain and his heart is an artist" -- Louis Nizer

  3. #13
    Jim Moore's Avatar
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    Quote Originally Posted by roteague
    Is is possible to purchase Pyrocat-HD in powder form? I have neither the time, nor inclination to mix chemicals myself.
    You can get it in a liquid kit from Bostick & Sullivan

    http://www.bostick-sullivan.com/welcome.htm

    Jim
    "You miss 100% of the shots you don't take"...Wayne Gretzky

  4. #14
    roteague's Avatar
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    Quote Originally Posted by JMoore
    You can get it in a liquid kit from Bostick & Sullivan

    http://www.bostick-sullivan.com/welcome.htm

    Jim
    I couldn't find it in the product list. Are they using a different name for it?
    Robert M. Teague
    www.visionlandscapes.com
    www.apug.org/forums/portfolios.php?u=2235

    "A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; a man who works with his hands and his brain and his heart is an artist" -- Louis Nizer

  5. #15
    Jim Moore's Avatar
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    Quote Originally Posted by roteague
    I couldn't find it in the product list. Are they using a different name for it?
    They still must not have it listed. When I ordered it I had to call.

    Just give them a call and tell them you would like to order the liquid Pyrocat-HD kit and they'll know what you're talking about.

    Jim
    "You miss 100% of the shots you don't take"...Wayne Gretzky

  6. #16
    Jeremy's Avatar
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    It's listed after the rest of the pyro chemicals, so you'll have to go one page down from where you think it should be alphabetically: $29/50 quarts working solution. I bought some that should be here later this week.

    edit: here's a link, it's right at the top.
    http://bostick-sullivan.com/commerce/aa_41.htm
    Last edited by Jeremy; 11-30-2004 at 12:39 PM. Click to view previous post history. Reason: added link
    Let's see what I've got in the magic trash can for Mateo!

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  7. #17
    roteague's Avatar
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    Quote Originally Posted by JMoore
    They still must not have it listed. When I ordered it I had to call.

    Just give them a call and tell them you would like to order the liquid Pyrocat-HD kit and they'll know what you're talking about.

    Jim
    Thanks Jim. I'll give them a call. I won't need it right away it looks like; I found out that because of all the humidity here, that all the negatives I have already shot are all sticking together. Ouch I've asked J&C about it, and he is asking the manufacturer, but I will probably have to chalk this up to a learning experience and reshoot. No big deal, I didn't shoot anything serious yet, just something to get my hand in doing B&W again.
    Robert M. Teague
    www.visionlandscapes.com
    www.apug.org/forums/portfolios.php?u=2235

    "A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; a man who works with his hands and his brain and his heart is an artist" -- Louis Nizer

  8. #18

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