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  1. #1

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    Two tricks for measuring and quickly dissolving Phenidone

    My propylene glycol hasn't arrived yet, so I had to be creative. What do folks think of these two tricks?:

    Trick #1: Measuring small amounts of Phenidone for use with PC developers only:
    Weigh 1 gram of Phenidone into a small bottle that can be capped. Crush all clumps of Phenidone.
    Add 9 grams of Ascorbic acid to it, making 10 grams total.
    Cap, and shake the bottle well to mix the two powders.
    This gives you a 10% mixture. So when a formula requires .12 g of Phenidone, for example, measure out 1.2 g. But remember to calculate how much Ascorbic acid this is also giving you and subtract from the vit-C you'll be adding.

    Trick #2: Dissolving quickly:
    A couple of books say that Phenidone dissolves well in alkaline solutions.
    So add the strongest alkali to the hot water first (such as sodium carbonate).
    Then add the Phenidone.
    For me, the Phenidone dissolved in 1-2 minutes at 50 degrees C, much faster than the 4-5 minutes it usually takes.

    I know, I know, just mix Phenidone into a 1% solution of PG (once you have some) and forget everything above.
    Any comments? Can Phenidone survive long when mixed with Ascorbic acid powder?

    Mark Overton

  2. #2
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    Two bad ideas! Sorry.

    Mixtures of powders tend to separate based on weight and crystal habit (size and shape). You end up with a non-uniform mix that even shaking will not fix.

    Adding the developing agents to alkali without Sulfite allows quick oxidation which leads to irregular results.

    Good luck to you.

    PE

  3. #3

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    Quote Originally Posted by Photo Engineer View Post
    Two bad ideas! Sorry.
    Mixtures of powders tend to separate based on weight and crystal habit (size and shape). You end up with a non-uniform mix that even shaking will not fix.
    Adding the developing agents to alkali without Sulfite allows quick oxidation which leads to irregular results.
    PE
    I didn't think of that aspect of mixing powders, and thanks for pointing it out. Phenidone and ascorbic acid are both very fine (flour-like), and when mixed, their particle-types became visually indistinguishable. It's anyone's guess if separation would be an issue between these two. BTW, the activity I got was exactly as expected, so it looks like I got away with it once anyway.

    Sulfite is added immediately after the Phenidone, so it would be unprotected only for the time it takes to dissolve it and measure/add the sulfite, which would be around 3-4 minutes. How much extra oxidation would occur at 50C for 3-4 minutes? I'm hoping not much...

    Mark "waiting for that PG to arrive" Overton

  4. #4
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    Oxidation is instantaneous.

    Separation of solids is variable and hard to detect and measure. Maybe you are lucky but it may not be the case for everyone.

    PE

  5. #5

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    Back in my geology days we used to grind rocks to powder for analysis - typically around 30 microns grain size. One thing we knew (and had tested) was that powders on the shelf tended to separate by mineral density and grain shape. Vibration, even temperature changes, was enough to cause the powders to stratify a little. To compensate we had to put the bottles of powder in a turbulator - a device that performed a sort of three-dimensional figure eight motion. This homogenized the powder enough that repeated samples gave the same analysis to 5 parts per million detection. At least with rock powders we had ground the material to a consistent grain size and had broadly similar mineral chemistry and density. I doubt that a two component mixture, hand ground and shaken would give repeatable results.
    I feel, therefore I photograph.

  6. #6

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    Quote Originally Posted by Photo Engineer View Post
    Oxidation is instantaneous.
    PE
    It sounds like a little sulfite should be added before the phenidone in the original posting. Which reminds me of the admonition, "Add a pinch of sulfite before adding the metol". But I have a hard time believing that a "pinch" of sulfite would help much in nearly a liter of water. I notice that FX-1 and Beutler both call for 5 g/L of sulfite, which may well be the minimum needed to protect the developer. Which brings me to my question:

    How much sulfite is needed to protect the developer? Is a pinch or 5 g/L enough?

    Mark Overton

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    The idea with a pinch of Sulfite is to scavenge dissolved Oxygen in the water. There is not much, but on a molar basis, this can hurt the developing agent(s). I add my sulfite from the start, and 5 - 10 g/l is a good starting point but it depends on what you really want to do with the Sulfite. Remember that Sulfite turns into Sulfate when oxidized. It therefore becomes inactive.

    PE

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    Why bother with this sulphite business at all?

    Just weigh out a gram or maybe two of phenidone, and the dissolve it in denatured spirits, it will keep well in a capped bottle....

    1 gram in 100 ml, 1 ml equals 0.01 gram and can be safely added to most any developer, the amount of alcohol can be nbeglected in most cases.

    I have used this with success with Parodinal (better called Tyrodinal, since it is based on Tylenol), as has a friend of mine with eqqual success, he has even used it with success, mixing PC-Glycol.............



 

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