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  1. #241
    Photo Engineer's Avatar
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    Rudeofus:

    I had wondered that same thing, but didn't bring it up. His developer is nothing like ours so I didn't think of it in this context. So yes, he may have gone down the same path but with a different formula. Very good idea to try a very long development time and see what happens.

    PE

  2. #242

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    Mark,
    I developed APX100 24min 20C and got good negs in your last posted brew.Maybe a bit overdeveloped.
    Gainer found that to get max contrast for a given development time you need 40:1 ascorbate/phenidone ratio.
    http://unblinkingeye.com/Articles/Sy...synergism.html
    Xtol has about this ratio.
    With no buffer to get pH~8 you have 2.7:0.18 only 15:1.
    So you have to develop a lot longer than Xtol to get the contrast.
    Last edited by Alan Johnson; 01-03-2012 at 01:00 PM. Click to view previous post history.

  3. #243

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    With TMX film my normal XTOL times at 1+3 are over 20 minutes.

  4. #244

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    Quote Originally Posted by Alan Johnson View Post
    Mark,
    I developed APX100 24min 20C and got good negs in your last posted brew. (snip) With no buffer to get pH~8 you have 2.7:0.18 only 15:1.
    So you have to develop a lot longer than Xtol to get the contrast.
    How does the grain look compared to other developers you've used? Hmm, at 100 speed, maybe you'll need a 100x microscope to tell. Also, did the developer turn yellow? And what agitation-method do you use? I agitate for 6 sec, once per minute.

    Regarding 15:1: The paradox is that this formula is the nearly the same as PC-Sulfite, except for a different alkali. And PC-Sulfite only needs around 7.5 minutes, operating at the same pH. I've been thinking that dissolved oxygen was destroying ascorbate, but maybe not.

    Quote Originally Posted by Rudeofus View Post
    could you find out whether that clip ever turns normal if you dev long enough? (snip) If your test clip turns normal after much longer dev, it would be interesting to see results, especially with regard to grain. On the one side you achieved extra slow development, on the other side you omitted Na2SO3 which acts as a grain solvent.
    I'll re-mix and try that, but it looks like Alan beat me to it. Anyway, I'll try both normal and continuous agitation.
    The possibility of micro-crippling due to poor buffering also occurred to me while driving to work this morning. I got some thin-but-probably-usable negs, and I'll re-examine them for shadow-detail.

    TEA has some solvent ability, so 20+ minutes in it might do nice things for the grain. Although at only 5 ml/L, I'm not holding my breath.

    For those who want to experiment with this, you can multiply the amount of TEA and AA by the same factor, and the pH will change only slightly. That might be a way to get enough TEA in there to improve buffering and get some solvency-effect. Also, the AA/phenidone ratio will rise by that factor, which will also increase activity somewhat proportionately until levelling off after the ratio goes above 40.

    Mark Overton
    Last edited by albada; 01-03-2012 at 05:33 PM. Click to view previous post history.

  5. #245

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    You might keep an eye open for an increase in shadow speed.
    Sometimes when a developer takes a long time to reach normal contrast this gives the shadows extra time to develop.Maybe not with sulfite as some of the latent image specks are dissolved, but TEA may do this.

  6. #246

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    Following Alan's example, I developed the new strip for 20 minutes at 20.5C. The results compared to XTOL:

    • Slightly higher overall density.
    • Higher fog.
    • Grain is significantly coarser.
    • Slightly less shadow-detail (i.e., loss of speed).

    It seems to me that this developer needs a halide-solvent to improve grain and speed.

    Mark Overton

  7. #247

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    Quote Originally Posted by Photo Engineer View Post
    Well, try using Potassium Sulfite.
    Regarding solvent-power, how much Potassium Sulfite should I use? The molar-equivalent of Sodium Sulfite?

    I ordered some 48% concentrate today, along with Dimezone-S.

    Mark Overton

  8. #248

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    Quote Originally Posted by albada View Post
    It seems to me that this developer needs a halide-solvent to improve grain and speed.

    Mark Overton
    If you want a glycol only developer with no sulfite,it has been done. But it looks like quite a research project to me.
    http://photo.net/minox-camera-forum/00VpUe
    That has a lot of phenidone and little ascorbate as it is for microfilm.
    1,2-propanediol is propylene glycol.
    Notably is appears to use thiocyanate as silver halide solvent.
    There are hazards with this but thiocyanate is used in toner.

  9. #249
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    Mark;

    Start with the molar equivalent.

    PE

  10. #250
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    And make sure you properly account for bound water molecules when comparing sodium and potassium sulfite. IIRC both come with varying amounts of water per molar unit, make sure you know which one you have in front of you.
    Trying to be the best of whatever I am, even if what I am is no good.



 

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