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  1. #21

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    Quote Originally Posted by Lukas_87 View Post
    OXIDATION, for Christ's sake!
    Meaning what?
    Interesting statement BTW.

  2. #22

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    Quote Originally Posted by john_s View Post
    Why does this developer have long shelf-life?
    Soduim Sulfite.

  3. #23
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    I will answer these comments one at a time.

    1. In post #4 synergy with phenidone and AA is mentioned. I said it was not on the order of the synergy between HQ and Metol. Here is what Gainer says:

    "Phenidone is often described as the primary agent in developers like the one tested here. The secondary agent is said to regenerate oxidized phenidone to its original state. In fact, the ascorbic acid is a scavenger of anything that might be, at least in old-fashioned terms, a free radical. Oxygen in water solution is such, as is chlorine used as disinfectant. Halogen atoms set free from silver halides by photolysis or by phenidone are taken by ascorbate and converted to hydrobromic acid and dehydroascorbic acid. Phenidone is not lost in this process, but ascorbate is. The experiments presented here have shown that adding ascorbate to a phenidone-ascorbate developer above the amount that can be activated by the phenidone content will cause little change in developer activity. The excess serves as a preservative and as a reserve."

    There is no synergy really mentioned here nor shown in the article to my satisfaction. He does, however, make a good case for AA being an effective antioxidant. So, I answered a specific comment and based it on the above comments by Gainer.

    2. Fenton is the well known iron - peroxide caused decomposition of reductants in solution, and the basic cause of instability of AA developers in the opinion of some. It is said to be offset by salicylic Acid and other sequestering agents added to developers. See the many threads on this subject here.

    3, The correct spelling is OXIDATION!

    4. I am a chemist and so is Gerald Koch.

    PE

  4. #24

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    Quote Originally Posted by Photo Engineer View Post
    3, The correct spelling is OXIDATION!
    Thanks for correcting me on that.
    Very important.
    Enligsh (US or UK variant) isn't my first language, so you have to live with that.

    If you can't stand a few spelling errors, please stop reading my threads/comments.

    You have now proved that you can safely be ignored.
    Welcome to my ignore list!

  5. #25

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    If you can't stand a few spelling errors, please stop reading my threads/comments.
    I stopped reading when it just got rude.

  6. #26
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    And here I was answering Lucas' post. The spelling of Oxidation and the Fenton reaction are both easily accessed in Wikipedia. The instability of AA developers is widely known and commented on here and on PN.

    Please note that Gainer himself does not seem to claim superadditivity with AA and Phenidone in his conclusions even though the title of that article suggests it.

    Also, on another note, Phenidone is not the "best" developing agent of this class of chemical. The generic class is derived from a hydrazine and the class includes Phenidone as the root, then Dimezone and finally Dimezone-S. Each is better than the previous developing agent, and each is more and more stable against hydrolysis in an alaline developer. That hydrolysis or decomposition of Phenidone may contribute do the instability of any Phenidone developer.

    It is nice to know that one is being ignored by someone in apparent need of ones help.

    PE

  7. #27

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    Tronds, you're taking this all too personally. These guys are just trying to help. You've made several assertions regarding the working properties of your formula without the evidence or scientific basis to back them up, so you have to expect to be challenged a little. Also, PE is one of the last people to ignore on APUG, particularly if you're interested in photographic chemistry.

  8. #28

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    Quote Originally Posted by Michael R 1974 View Post
    Tronds, you're taking this all too personally. These guys are just trying to help. You've made several assertions regarding the working properties of your formula without the evidence or scientific basis to back them up, so you have to expect to be challenged a little. Also, PE is one of the last people to ignore on APUG, particularly if you're interested in photographic chemistry.
    I don't care. So much incorrect information and hangups in spelling errors shows that there isn't really much information or help to get.
    There are other places to get correct information.

  9. #29

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    Quote Originally Posted by mwdake View Post
    I stopped reading when it just got rude.
    That's ok by me, but you are still reading?

  10. #30

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    I am leaving this thread now.
    You can still comment and discuss, but I don't care to keep discussing. The recipe is published and it is free for everyone to test it.
    If someone can come up with a better result, feel free to comment on the blog.
    Do your homework first. Run a test and have a close look at the results. Theory is fine, but it is the real results that counts.

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