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  1. #11

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    Quote Originally Posted by brianmquinn View Post
    You said,
    "sodium metaborate/Kodalk/Balanced Alkali.
    I put 1/4 tsp in 100ml of glycol, which is about 1.2 grams.
    I then diluted it 1:9 and got a pH of 9.1
    I doubled the water and the pH is 8.6
    Doubling again to 400ml, down to 8.2
    Very effective buffering.
    Obviously one can alter the amount of metaborate to meet a target pH in dilution."

    A 10 fold dilution of an acid (Like HCl) OR base (LIKE NaOH) with NO buffering will show a ONE pH unit change. I don't know why you would get such a large change in pH with just doubling (twice) the amount of water. Are you using pH test strips that may be interacting in a strange way with the other chemicals in your mix?
    I can only tell you what I measured. Yes, pHydrion strips, but no, no other chemicals in this simple mix. The colors, for once, were spot on the comparisons printed on the label.

  2. #12

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    In the thread on Progress on XTOL-concentrate, I stated that I had discovered that sodium metaborate dissolves in propylene glycol. It turns out that I was not the first to discover this (or publicly disclose it, anyway). That honour might belong to Paul Verizzo:

    Quote Originally Posted by Paul Verizzo View Post
    Then I wondered about the sodium metaborate/Kodalk/Balanced Alkali. It went into solution like sugar in water.
    There you have it. He discovered it 3.5 years before I did. And it's an important discovery because sodium metaborate is a useful enough alkali in developers that Kodak practically named it after itself ("Kodalk").

    BTW, does anyone know where Paul went? This site says his last posting was 1.5 years ago.

    Mark Overton

  3. #13

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    Quote Originally Posted by albada View Post

    BTW, does anyone know where Paul went? This site says his last posting was 1.5 years ago.

    Mark Overton

    Boo!

    I've not been active in photography/photochemistry in that time frame. Seems like more time, frankly. Assorted reasons, most due to my life and changing interests, having little to do with photography. But one does:

    I'm not a master printer, not by a long shot. But I can crank out decent prints on a good inkjet, have me a wide carriage Canon. Sooooo........ I came around to using Kodak HD 400 (discontinuted) and Ektar 100 as universal films. Although I've putzed plenty with developing my own C-41, for reliability I'd get it developed for $3-5, scan it, then I could manipulate and print via computer and Epsons in either color or B&W.

    The long exposure curves and extremely fine grain give results hard to attain (especially together) in B&W films.

    Funny, in the last 24 hours I was looking at my enlarger and knowing that I will be cleaning out the house within a year, wondering if it was time to be rid of it. And what about my (refrigerated) papers, my (refrigerated and lead bagged) films, and my chemicals. Sad.

    Now here's a time marches on sadness: I live in Sarasota, Florida, a burg of some 50,000 full time residents. There was a camera store downtown that grew into a regional chain when we moved here in 1959. In fact, the house we bought was from the owner of those stores. Anyway, long closed down, now a restaurant, what else? Further anyway, the last "real" camera/photo store has announced their dissolution, a Wolf Camera. Good staff, always fun to poke around and see what's on sale, my preferred C-41 developer.

    A few days ago I met this young woman, recently out of college, not sure how the topic came up, but she said, "I had a film camera once when I was a little girl."

    Sigh.

  4. #14

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    There was a long thread a little while ago about Suzuki's use of TEA and salicylic acid as chelating agents in ascorbate developers to prevent the sudden death syndrome. Small amounts of TEA were used for that; it was not used as a solvent. In any case, such small additions might be valuable in a PC-Glycol developer.

  5. #15

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    Quote Originally Posted by nworth View Post
    There was a long thread a little while ago about Suzuki's use of TEA and salicylic acid as chelating agents in ascorbate developers to prevent the sudden death syndrome. Small amounts of TEA were used for that; it was not used as a solvent. In any case, such small additions might be valuable in a PC-Glycol developer.
    It was suggested that Suzuki explored TEA and salicylic acid because alternatives were hard to get. Kodak uses DTPA in XTOL, and I've found a couple of places to get it:


    It isn't cheap, but quantities are large enough that you'll only need to buy it once. Also watch out for the difference between pure DTPA and the DTPA-Na5 (pentasodium salt) that Kodak uses. For a concentrate such as glycol-metaborate, the pure stuff should be soluble in organic solvents and the salt might not be (posted by the chemist, Gerald Koch, in another thread).

    Mark Overton

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