Ascorbic Acid Developer

Discussion in 'B&W: Film, Paper, Chemistry' started by drpsilver, Jun 11, 2012.

  1. drpsilver

    drpsilver Subscriber

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    10 June 2012

    I "inherited" a bottle of ascorbic acid crystals, and thought now is the time to try an XTOL like developer. I am looking for developer formulations that work well with Tri-X and HP5+. Any suggestions?

    With this acquisition came a bottle of calcium ascorbate. Is this of any use in creating a developer?

    Regards,
    Darwin
     
  2. komla

    komla Member

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    Caffenol?
     
  3. Murray Kelly

    Murray Kelly Member

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    If you want to experiment with the calcium salt remember that carbonates and hydroxides will precipitate a cloud of insoluble calcium carbonate or hydroxide. Sulfites and borates are marginally soluble in water so that makes borax and sufites a poor choice and I have tried some with triethanolamine (TEA) as the alkali and that was apparently OK. No cloudiness. Also Calgon will make a good strong alkali solution and the calcium certainly shouldn't precipitate. That's what it's for, after all.

    You could just eat the stuff and keep healthy, too.
     
    Last edited by a moderator: Jun 11, 2012
  4. Athiril

    Athiril Subscriber

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    Photographically, how do the calcium salts differ from sodium and potassium? It's said potassium is more photographically active than sodium.
     
  5. Gerald C Koch

    Gerald C Koch Member

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    Calcium ascorbate is rather useless for developers since it will precipitate calcium sulfite from most developer formulations. Do you have a required primary developing agent like Phenidone, Dimezone, or Metol?
     
  6. drpsilver

    drpsilver Subscriber

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    11 June 2012

    Murry:
    I had forgotten about the possibility of carbonate and hydroxide precipitation. Thanks for the "heads-up"

    Gerald:
    I have a good supply of hydroquinone and metol.

    Thanks to all for your comments.

    Regards,
    Darwin
     
  7. Rudeofus

    Rudeofus Subscriber

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    Please note that this will not just be a possibility, but a big certainty. Most devs work only in caustic environments with pH levels above 8 or 9, and at these levels you will inevitably get Ca(OH)[SUB]2[/SUB] precipitation, regardless of which caustic you used to raise the pH.

    In theory, you could chelate away the calcium with EDTA, but the required amount of EDTA will be much more expensive than fresh ascorbic acid. If you still want to play with ascorbate developers, look at Mark Overton's (aka albada) recent thread. Lots of info to be found ...
     
  8. Alan Johnson

    Alan Johnson Subscriber

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  9. jm94

    jm94 Member

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    If you don't mind me asking, what is Ascorbic Acid's purpose when used in a developer? I am interested to know :smile: I too have loads of crystals, but as a vitamin supplement, not the raw form of it.
     
  10. Gerald C Koch

    Gerald C Koch Member

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    Ascorbic acid is a developing agent that is used in place of hydroquinone because it is non-toxic. However the action of these two agents is quite different. When used alone ascorbic acid is very slow in its action and has a long induction period. For this reason it is most often used in a super-additive mixture with Metol or a Phenidone derivative.
     
  11. Rudeofus

    Rudeofus Subscriber

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    There may or may not be significant differences between the pictorial results of AA and HQ, but in respect to the above AA and HQ are very similar, at least for moderate pH levels.
     
  12. Gerald C Koch

    Gerald C Koch Member

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    My statement concerned the chemical properties of the two agents not the pictorial results although these are also different. Any resemblence between the two agents is superficial. For example, AA gives finer grain the HQ. As to the chemical properties the oxidation product of HQ, the monosulfonate, is also a devfeloping agent. This is not true for AA. Also AA produces little infectious development. There are other differences which I will not go into in this post.
     
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  13. jm94

    jm94 Member

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    Ah i never realised it could be used as an ACTUAL developing agent, I might give that a try, I don't reckon it would last long once mixed? like rodinal as Vitamin C is unstable Also, what about using a salt of ascorbic acid, such as sodium ascorbate? does it require the molecule ascorbic acid on its own or can it still do its action, bound to the sodium? Also what about ascorbic acid esters? I always knew sodium ascorbate to be more stable, at least I think it is...
     
  14. Michael R 1974

    Michael R 1974 Subscriber

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    In XTOL it is sodium isoascorbate. Not sure if that helps answer your question (I'm not a chemist).
     
  15. Gerald C Koch

    Gerald C Koch Member

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    Isoascorbic acid is slightly more active as a developing agent. This isomer is more commonly called erythorbic acid. The sodium salt of either agent can be used in developers and do not require added alkali as the acid does. Erythorbic acid also tends to be a bit cheaper. What does the developing is the ascorbate ion which is produced by either ascorbic acid (think hydrogen ascorbate) or sodium ascorbate when dissolved in water.
     
    Last edited by a moderator: Jun 25, 2012