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  1. #151

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    I don't think one can make a developer with a grain as fine as Xtol starting from a sulfite glycol concentrate.
    The working solution of Xtol has 85g/L of the grain solvent sodium sulfite (FDC p49)
    One would need to find an organic sulfite completely miscible with glycol and use a great excess of it if the mixture is to be both a concentrate for dilution and provide 85g/L sulfite equivalent in the working solution.
    Even if it was possible it would be wasteful and expensive.
    Perhaps one could consider if there exists a stronger grain solvent than sulfite that is soluble in glycol.

  2. #152
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    Alan, there are several silver halide solvents that fit your criteria. EK R&D people were working with a whole family of them when the work was shut down.

    Jerry, think about antifreeze formulas all over the world! Each one may differ enough to cause problems in otherwise identical developer formulas and that is one of the problems using antifreeze.

    PE

  3. #153

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    Quote Originally Posted by Alan Johnson View Post
    Perhaps one could consider if there exists a stronger grain solvent than sulfite that is soluble in glycol.
    Alan, funny that you should mention this. If you go back in this thread a few pages, there are a few postings where Ron and I talked about this. I read Ron's patents and got some ideas, and Jerry also contributed a couple of suggestions, such as Cysteine (pure; not a salt). Even if no halide solvent is workable, I have no problem mixing the sulfite separately from the concentrate. Sulfite doesn't need to be measured very accurately, and I noticed that a plastic film-canister holds 96 g of sulfite. So fill one almost full, and that's what Xtol/Mytol need for a liter. Or half full for 500 ml (2 rolls). My point is that folks can use a concentrate/sulfite duo conveniently enough, so we really don't need to incorporate the solvent into the concentrate. That's makes engineering a concentrate that much easier.

    Mark Overton

  4. #154

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    Funny how negative this is perceived, as a chemist one should rather encourage experiments.....

    And as far as I'm concerned Ron, your developers currently on sale simply does not exist! Never heard of them, never seen them on sale anywhere, and they sure as hell never WILL BE on sale here, because supply and demand dictates that such an esoteric piece of trade as pre-packaged film developers will not sell to anyone but two crankpots in this entire country - and its getting worse.

    Me getting into home-brew developers, this late in history, when I can no longer walk up to the counter of the closest city Merk's representative and order all kinds of fancy chemicals and have many of them handed me straight over the counter, is a precaution, I just wanna be able to develop films as long as I CHOOSE, not being dictated by businesspeople, by the looks of it I will still be able to find outdated film until I'm approaching 80, so thats what I concentrate on, nothing else is available here any longer, we have been digitalized.

  5. #155

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    The simple solution to PC-glycol and the concentration of silver solvents is suimply to add them with the water!
    After all glycol is just a CONTAINER!!

  6. #156

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    I followed Jerry's suggestion, and tested the components in water first, in order to verify and tweak the formula, before attempting the PG. Here's the one-liter formula I ended up with:


    Ascorbic acid ..................... 10.7 g
    Sodium metaborate ............. 9.5 g
    Boric acid ........................... 4 g
    Sodium sulfite ..................... 90 g
    Phenidone .......................... 0.15 g (I used a 1% solution in PG)

    Target pH is 8.2 (same as XTOL). Same development-times as XTOL.
    The ascorbic acid combines with 4g of the metaborate to form 12 grams of sodium ascorbate.

    I tested this scaled down to 200 ml, 6.5 minutes at 20C for TMY.
    The results compared to an identical negative from the same roll developed in XTOL under the same conditions:
    Same density (gauged visually). Same sharpness. Possibly a hint more grain. A hint more shadow-detail. Possibly a hint more fog.
    I think most people could not tell the difference between this and XTOL.

    My concern now is that 24 grams of powder may be too much to dissolve into 50 ml of PG (1+19 dilution), and might not even be possible for 100 ml (1+9 dilution).

    Tidbit: I read in either the FDC or TDC that boric acid is very slow to dissolve. I discovered that it dissolves almost instantly in near-boiling water. Heating a separate beaker containing a little water for only the boric acid means you don't need to heat the entire working solution.

    Mark Overton

  7. #157
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    Very nice. Congratulations.

    Look up Boric Acid in Wikipedia. That may give some help.

    PE

  8. #158
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    AWIT;

    The reason I mentioned my developers is twofold. One is to show that a new formula can be compounded in a home lab and can be sold commercially! the second is that this particular developer embodies many of the solutions to problems posed in this thread. It uses electron transport chemistry to give long life to the developer with no change in activity. It is primarily a paper developer, but a film developer is on the books and that uses a new type of Silver Halide solvent.

    So, I am working here at home on a number of new solutions to problems that you all are considering. I have the advantage of knowing what was being worked on when these projects were cancelled at EK.

    PE

  9. #159
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    Quote Originally Posted by analog what is that? View Post
    Naaa that is an argument without any practical merit in THIS context.
    We are not developing color films you know, (most of us) are not printing in the darkroom any more, fewer will in the future.
    We employ a modern gizmo called a scanner. This thing cuts through bot fog and color dyes like a knife in butter.
    It is also fully color sentisive, so we can scan any color we, like and change the colors afterward or even turn the thing into B/W with just one click on a virtual button...

    So this was an answer looking for a good question....

    For your information we come from a running debate on Caffenol, where the guys demand to exchange KBr with iodized table salt, large amounts of it, and accept the acompanying yellow stain as if nothing happened....
    Why is this on APUG?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  10. #160
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    Quote Originally Posted by MattKing View Post
    Why is this on APUG?
    Matt;

    I asked myself the same question but gave it a pass in the spirit of the holidays.

    Maybe I should have resisted the holiday urge!

    PE



 

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