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  1. #1
    Ian Grant's Avatar
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    Modern Rodinal Substitutes Part II

    Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

    So with a bit of telepathy

    Quote Originally Posted by Kirk Keyes View Post
    Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

    But for MSDS work, it doesn't have to be too precise.
    __________________
    Kirk

    A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

    The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

    Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

    Can someone please post a link to this continuation on the original post.

    Ian

  2. #311

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    Quote Originally Posted by Photo Engineer View Post
    Benzyl Alcohol ... It has not relationship to the present discussion in any way.
    Oh well...

    I think there is a hazard to having the last post on a page. People always seem to skip right past them onto the next page...
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  3. #312
    gainer's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Ian;

    I know nothing about benzene sulfonate itself as an antioxidant.

    As for the properties of benzene sulfonates or p-tosylates as antioxidants or as helpers in dissolving, it is known from fundamental chemistry that organic aryl amines (metol, pAP, and PPDs) all oxidize rapidly as free bases and dissolve slowly as free bases. If they are predissolved in an equmolar solution of ANY acid, then they dissolve much more rapidly in water and they are much more resistant to aerial oxidation


    PE
    So help me, I am not trying to make fun of you but of myself. I was trying to remember where I used the term "PPD" before. Suddenly it came. It is from a previous life and there it means "Post Prandial Depression", which is what makes one want to fall asleep after a meal. It is an important part of Human Factors Research.
    Gadget Gainer

  4. #313
    gainer's Avatar
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    Quote Originally Posted by Kirk Keyes View Post
    Oh well...

    I think there is a hazard to having the last post on a page. People always seem to skip right past them onto the next page...
    Don't feel neglected. I have had it happen that the last post on a page when I started a reply was not the last post when I finished my post, so my post skipped one.
    Gadget Gainer

  5. #314
    Photo Engineer's Avatar
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    Quote Originally Posted by gainer View Post
    So help me, I am not trying to make fun of you but of myself. I was trying to remember where I used the term "PPD" before. Suddenly it came. It is from a previous life and there it means "Post Prandial Depression", which is what makes one want to fall asleep after a meal. It is an important part of Human Factors Research.
    I'll use pPD then in the future to denote the para or lower case "P". I'm glad you were wide awake.

    PE

  6. #315

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    Quote Originally Posted by gainer View Post
    It is from a previous life and there it means "Post Prandial Depression", which is what makes one want to fall asleep after a meal.
    What do they call it when after looking at screen after screen of mass spectral data, you start to fall asleep? That's what was just happening to me. (But then is a bit after lunch too...)
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  7. #316
    gainer's Avatar
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    Quote Originally Posted by Kirk Keyes View Post
    What do they call it when after looking at screen after screen of mass spectral data, you start to fall asleep? That's what was just happening to me. (But then is a bit after lunch too...)
    You see? That is why it is so important in the study of Hunan Factors. Even piloting an aircraft can be a boring task. Another factor is the homing instinct. It has been known to make a pilot so anxious to get home that he does not go around on a landing attempt when he really should have.
    Gadget Gainer

  8. #317

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    This has been fascinating, even if hard for me to follow. However, being a dumb farmer, I can talk about the use of surfactants in relationship to pesticides. They are used to slow down the evaporation of the water content of the spray, increasing it's effectiveness. The best surfactant I ever used was 1 quart of #2-D diesel fuel and 2 capfuls of Dawn dishwashing detergent per 300 gals of tank mix.



 

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