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  1. #11

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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.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  2. #12

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    Neopan SS @100, 20min stand in RD-107
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  3. #13

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




  4. #14

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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





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  5. #15
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    Quote Originally Posted by Gerald C Koch View Post
    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.
    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.
    Trying to be the best of whatever I am, even if what I am is no good.

  6. #16

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    Quote Originally Posted by Alan Johnson View Post
    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.
    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

  7. #17

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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.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  8. #18

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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 Relayer; 08-07-2012 at 12:25 PM. Click to view previous post history.

  9. #19

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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.

  10. #20

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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)

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