Phenidone-ascorbate developers at low pH~7

Discussion in 'B&W: Film, Paper, Chemistry' started by Relayer, Jun 14, 2012.

  1. Relayer

    Relayer Member

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    Hello

    I once read that developing film in Diafine bath A for 40-50 minutes produce some thin image. This is very interesting, because this bath contains P+Q in acid solution. So for testing I was replcae Q with C and mix next:

    RD-107 developer
    Sodium sulfite 30g
    Phenidone 0.2g
    Sodium ascorbate 4g
    Sodium metabisulfite 5g
    Water 1l
    pH 7.2

    for Neopan SS 100 (expired) I found next development time: EI 100 - 20min, EI 200 - 30min, EI 400 - 50min. all done at 23C and WITHOUT AGITATION! just first 1min initial agitation and leave stand for rest time.
    Negatives obtained is very clear and fine grain

    PS if you ommit phenidone from formula - you will have blank film. so phenidone is important part
     
  2. Alan Johnson

    Alan Johnson Subscriber

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    Looks interesting. Could it be made up as a concentrate to be diluted 1+3? At this pH it should keep quite well in a sealed bottle.
     
  3. Relayer

    Relayer Member

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    concentrate isn't need because developer can be reused.
    at low pH solution have long keeping time. in my experiment I was initially try Diafine-C bath A 1 year old - its work!
     
  4. Gerald C Koch

    Gerald C Koch Member

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    Since the first bath of a two bath developer is meant to be saved and used again you really need to include an appropriate chelating agent. No doing this may result in an Xtol style sudden death. The need for a chelating agent with ascorbate developers has been extensively discussed on APUG.
     
  5. Relayer

    Relayer Member

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    Salicylic acid + TEA ?
     
  6. Michael R 1974

    Michael R 1974 Subscriber

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    Relayer - is the ascorbate active at all at that pH?
     
  7. Gerald C Koch

    Gerald C Koch Member

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    Better than using nothing. However, people who use two bath developers keep the first bath for so long that a more powerful chelating agent might be needed. The problem is that such agents are not readily available to the public. More than anything else this problem limits the usefulness of an ascorbate based two bath developer.
     
  8. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    Would EDTA or Hexametaphosphate (old-style Calgon) work, or do you think a mercaptan is needed?
     
  9. Gerald C Koch

    Gerald C Koch Member

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    EDTA and sodium hexametaphosphate both accelerate the degradation of ascorbate. The choice of a suitable chelating agent is limited. A mercaptan can cause fogging and they are poor chelating agents. There is little data available as to which chelating agents are useful and which are not.

    What may not be understood is that the oxidation of ascorbate is a kinetic reaction. The choice of chelating agent is one the factors that determines the speed of the reaction. The reaction can be slowed but it is never completely stopped.
     
    Last edited by a moderator: Jun 15, 2012
  10. Rudeofus

    Rudeofus Subscriber

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    PhotoEngineer has recommended Dequest 2010, which is an extremely potent iron sequestrant. When you use it, be aware that it is very acidic. Since the TO lives in Europe: Fototechnik Suvatlar sells it under the name Fotoplex 2.
     
  11. Gerald C Koch

    Gerald C Koch Member

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    The problem with Dequst, and for that matter other chemicals, is to find a supplier of small quantities that will sell to the public. This was a factor in the selection of salicylic acid as it was readily available.
     
  12. Relayer

    Relayer Member

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    Neopan SS @100, 20min stand in RD-107
    scan 2400dpi, epson 4180

    [​IMG]

    [​IMG]
     
  13. Relayer

    Relayer Member

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    LegacyPro400 @400. 25min stand at 24C. slightly overdevelopent ~+1/2 stop. scan 2400dpi without postprocessing

    [​IMG]

    [​IMG]
     
  14. Relayer

    Relayer Member

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    formula revisited. reason is improved buffer at low pH

    RD-107F developer
    Sodium sulfite 30g
    Phenidone 0.2g
    Sodium ascorbate 4g
    Sodium Carbonate anh. 1.2g
    NaH2PO4•H2O 4g
    Na2HPO4•2H2O 7g
    Water 1l
    pH 7.2

    Sodium Carbonate can be ommited, but amount of NaH2PO4 must be increased for keep pH 7.2

    LegacyPro 400@400. RD-107F 25С 16min stand

    [​IMG]

    [​IMG]

    NeopanSS 100@500 (push +2) 25С 40min semistand. 30sec agitation after each 10min

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  15. Rudeofus

    Rudeofus Subscriber

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    I believe the reason it is śo difficult to get in the US is because it is considered a prescription medication there. I realize it won't help you much in the US of A, but you get Dequest easily in Europe from Fototechnik Suvatlar, where it is sold under the name Fotoplex 2.
     
  16. albada

    albada Subscriber

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    To change this to a concentrate based on propylene glycol, the sodium metabisulfite would need to be replaced with some other acid which is soluble in PG. I suggest replacing some or all of the sodium ascorbate (which can be difficult to find) with ascorbic acid. After this posting, Relayer posts a formula-change using monosodium phosphate to improve buffering. For a concentrate, your choices of acids and alkalis are limited. Common acids are ascorbic acid, boric acid and citric acid, and common alkalis are sodium metaborate, borax and TEA. And all this assumes that you'll be dissolving the sulfite separately.

    Anyway, I think I'll try this formula. It looks interesting, and thanks for posting it.

    Mark Overton
     
  17. Gerald C Koch

    Gerald C Koch Member

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    Some years ago I experimented with a PG-TEA based developer. However I found such formulations too restrictive in respect to what chemicals could be included in the mix. Add to this that the results were not any better than conventional developers. So I abandoned this idea.
     
  18. Relayer

    Relayer Member

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    upps. found error in formula. must be Ascorbic acid instead sodium ascorbate, and I forget about salicylic acid. so correct formula:

    RD-107F developer
    Salicylic acid 1g
    Sodium sulfite 30g
    Phenidone 0.2g
    Ascorbic acid 4g
    Sodium Carbonate anh. 1.2g
    NaH2PO4•H2O 4g
    Na2HPO4•2H2O 7g
    Water 1l
    pH 7.2

    if someone need "concentrate" for this developer I suggest next formula:

    Part A
    Phenidone 0.2g
    Ascorbic acid 4g
    Glycol 50ml

    Part B
    Salicylic acid 1g
    Sodium sulfite 30g
    Sodium Carbonate anh. 1.2g
    NaH2PO4•H2O 4g
    Na2HPO4•2H2O 7g
    Water 300ml

    1 part A + 6 part B + 13 part water
    for 300ml working solution need 15ml of A + 90ml of B and add water to 300ml
    for 500ml working solution need 25ml of A + 150ml of B and add water to 500ml
     
    Last edited by a moderator: Aug 7, 2012
  19. Alan Johnson

    Alan Johnson Subscriber

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    It's an interesting formula but I don't think photo chemical suppliers stock sodium dihydrogen phosphate monohydrate and dihydrate, they seem to be used in biology labs. One would need to re-work the formula with boric acid perhaps.
    The purpose of salicylic acid is to minimise iron catalyzed oxidation of ascorbate but since there is no ascorbate in part B of the concentrate it serves no purpose except to alter pH.Also note the solubility of Salicylic acid is only 2g/L.
     
  20. Relayer

    Relayer Member

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    Alan, phosphate buffer can be replaced back to sulfite-metabisulfite system as in 1st version. this isn't important for one-shot concentrate.
    salicylic acid easy dissolved after you add alkali (sodium sulfite, carbonate)
     
  21. albada

    albada Subscriber

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    Only 30g of sulfite is a low amount. Most developers have much more to help the Phenidone and improve buffering. Why did you choose that low amount of sulfite? Did more sulfite cause a problem?
    I'm asking because I want to try this developer, and it helps to know why quantities were chosen. I'm thinking of improving buffering by using more sulfite and more metabisulfite, but I don't want that to cause some other problem.

    Mark Overton
     
  22. Michael R 1974

    Michael R 1974 Subscriber

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    Seems similar to some modified POTA formulas.
     
  23. Relayer

    Relayer Member

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    this isn't true.

    Mark, small amount of sodium sulfite because I'm not need extra silver halide solvent in developer, which cause to less sharpness. You can try to increase concentration of sulfite to 50g/l and increase amount metabisulfite to keep pH=7.2-7.3
     
  24. Michael R 1974

    Michael R 1974 Subscriber

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    Whatever you say.
     
  25. Relayer

    Relayer Member

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    NeopanSS @800 (push +3), RD-107F 25C 45m stand: 1min initial agitation and 5 rotation after 25min

    [​IMG]

    [​IMG]