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  1. #1

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    RD-201: Phenidone-Pyrogallol true two bath

    Hello

    Phenidone with pyrogallol is superadditive and allow to make true two bath developer. Bath A have low acidic pH and developing start only in bath B. Developer increase speed by 1 stop and produce very sharp images.

    RD-201 developer
    Bath A
    Sodium sulfite 50g
    Phenidone 0,2g
    Pyrogallol 6g
    Sodium metabisulfite 6g
    Water 1l

    Bath B
    Sodium sulfite 30g
    Sodium carbonate 15g
    Water 1l

    Developing time 3min in each bath.

    Polypan F50 @64



    HP5+ @400




  2. #2

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    great work!

    does it stain / tan? just curious if the sod. sulfite prevents this.

    what would your opinion be about reformulating for catechol ( substituting the pyro )?

    have you looked to see if there is any development in A bath?

    i ask this because i once tried to formulate a metol only A bath with sod. metabisulfite 6g/Litre as the preservative. i used sod hydroxide as the B Bath. i increased the metol to 18g/Litre (from 8g ... gram by gram ) and only just started to get a faint image. i abandoned that idea because i could think of better formulas that used less metol.

    congrats on your formula.

  3. #3

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    Quote Originally Posted by el wacho View Post
    does it stain / tan? just curious if the sod. sulfite prevents this.
    it doesn't stain because sulfite in 2nd bath. but it will produce some stain if you omit sulfite. note that in this case 2nd bath is more like as one shot

    Quote Originally Posted by el wacho View Post
    what would your opinion be about reformulating for catechol ( substituting the pyro )?
    phenidone+catechol is less active that P+Pyrogallol
    you can try next formula

    bath A
    Sodium sulfite 50g
    Glycine 5g
    Phenidone 0.2g
    Catechol 5g
    Water 1l

    bath B - sulfite+carbonate. 3min in each bath

    Quote Originally Posted by el wacho View Post
    have you looked to see if there is any development in A bath?
    after 3min in bath A no any image

    Quote Originally Posted by el wacho View Post
    congrats on your formula.
    thank you

  4. #4
    pentaxpete's Avatar
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    Thanks for posting this -- I have all those chemicals and will try it out - I suppose you mean the Anhydrous forms of the Sodium Sulphite and Carbonate NOT the Hydrated forms ?
    An 'Old Dog still learning New Tricks !

  5. #5

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    A suggestion for further experimentation. Pyrogallol in the presence of sufficient sulfite behaves in much the same manner as metol. The Nietz-Tschibissoff series places them next to each other and their redox potentials are very similar. This would indicate that metol provides an effective substitute that is far less toxic, cheaper, and more stable than pyrogallol. This pairing of phenidone and metol is what Tetenal does in Neofin Blue.
    Last edited by Gerald C Koch; 09-20-2012 at 10:12 PM. Click to view previous post history.
    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

  6. #6

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    Quote Originally Posted by pentaxpete View Post
    Thanks for posting this -- I have all those chemicals and will try it out - I suppose you mean the Anhydrous forms of the Sodium Sulphite and Carbonate NOT the Hydrated forms ?
    sulfite and carbonate is anhydrous

    important note about 2nd bath: don't try to use borax! you will have blank film, because borax pH is very low.

  7. #7

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    Thanks for creating this developer and posting your results.
    A couple of questions:
    1. Have you done keeping tests, to see how long the developer will last? (6 months or more?)
    2. You said 1-stop speed increase. Do you have an accurate way of measuring the speed-gain?

    Anyway, good work!
    And good pictures also. You are a good photographer.

    Mark Overton

  8. #8

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    Quote Originally Posted by albada View Post
    1. Have you done keeping tests, to see how long the developer will last? (6 months or more?)
    now it keep ~3 month without any loss of performance. I think that developer can be keeping ~1year because acidic 1st bath

    Quote Originally Posted by albada View Post
    2. You said 1-stop speed increase. Do you have an accurate way of measuring the speed-gain?
    sorry, no. maybe I'm wrong, but negatives slightly dense than I like

  9. #9

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    Pyro produces a very nice (and unique) "look" regardless of staining. That is a good objective for a developer like this, and it is a reason not to substitute metol or catechol. With 6 g of metabisulfite, I would think the A bath is pretty close to neutral. That means it probably doesn't have great life, but it should be reasonable. I don't know if making it more acid would help, but it might.

  10. #10

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    Quote Originally Posted by nworth View Post
    Pyro produces a very nice (and unique) "look" regardless of staining.
    Unique, how do you know? Have you conducted blind evaluations with a group of people for various developers? We often see what we think we should see. Sorry but it's human nature.

    Producing a good print depends on the skill of the individual rather than in any "magical" properties of a particular developing agent.
    Last edited by Gerald C Koch; 09-21-2012 at 10:53 AM. Click to view previous post history.
    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

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