Parodinal With A Twist

Discussion in 'B&W: Film, Paper, Chemistry' started by MichaelMadio, Apr 15, 2011.

  1. MichaelMadio

    MichaelMadio Member

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    I've been experimenting with p-aminophenol/ascorbate developers lately. Since I had it around, I tried mixing parodinal with ascorbate and borax. There has been quite a bit written on adding some ascorbate and/or borax to rodinal to tweak it but I decided to take things in a slightly different direction with more ascorbate and borax. I made what I call RCB as follows:

    Water - 750mL
    Borax - 18g
    Ascorbic Acid - 6g (fully dissolve borax + ascorbic acid before proceeding)
    Parodinal - 20mL
    Water to make 1L

    Experimentation showed some interesting results. First, I can re-use this developer quite a few times without any loss of activity (I have processed 12 rolls from the same 1L of developer). Second, I can use it as a normal and stand developer. Third, it has the compensating characteristics of rodinal but with full speed and fine grain. Using this with 2-hour semi-stand development (5 mins pre-wet, 60 sec initial inversions, 10 sec inversions at 60 min, 120 mins total time) gives a consistent EI of +2 from box speed with the films I have tested (Plus-X, Tri-X, Neopan Acros, Neopan 400, Shanghai GP3, HP5+) providing good shadow detail, smooth highlights, and no fog. It is one of the few developers that I found can push Acros while taming contrast.
     
  2. Alan Johnson

    Alan Johnson Subscriber

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    By my calculation your formula is:

    Borax ..................................................18g
    Ascorbic Acid..........................................6g
    p-aminophenol as sodium aminophenolate.....1.04g
    Sodium Hydroxide.....................................0.96g
    Sodium Sulfite..........................................4g
    Water to.................................................1L

    I think it is an analog of the metol-ascorbate developers eg this from Pat Gainer:

    Borax.....................................................24.4g
    Sodium Hydroxide.......................................6g
    Ascorbic Acid............................................8g
    Metol......................................................0.8g
    Water to.................................................1L

    Metol is effectively replaced by p-aminophenol.

    P-aminophenol was dropped fairly early on in favor of metol which acts faster, but in solution p-aminophenol as aminophenolate is more resistant to atmospheric oxidation so your developer may keep better.
    It would be interesting to know if the pH of your developer is just over 9.
    IDK what is the pH of Gainer's formula but it maybe there is sufficient Borax to buffer it around this value.I don't think it is really known how well these metol ascorbate developers keep in full sealed bottles but would suggest store some of yours for a while and see if it still works would be interesting.
     
  3. MichaelMadio

    MichaelMadio Member

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    My last batch was around for over 5 weeks, used 12 times so lots of air, and showed no loss of activity at the end. I guess I could have kept going but I wanted to mix another batch to verify my results and so far, so good. I'll check the pH and report back when I get a chance.
     
  4. MichaelMadio

    MichaelMadio Member

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    pH is 9.3
     
  5. Relayer

    Relayer Member

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    I think that this formula can be rewrited in more simple form. 1st step:

    C6H8O6 + NaOH = C6H7O6Na + H2O

    0.96g NaOH + 4.23g Ascorbic acid = 4.76g Sodium ascorbate

    leave 6g-4.23g=1.77g Ascorbic Acid. 2nd step:

    2C6H8O6 + Na2B4O7 + 5H2O = 2C6H7NaO6 + 2H3BO3

    1.77g Ascorbic acid + 1.91g Borax = 2g Sodium ascorbate + 0.62g Boric acid

    rest 18g-1.91g=16.1g Borax. so formula will be next:

    Sodium Sulfite...........................................4g
    Sodium p-aminophenolate .......................1.04g
    Sodium ascorbate ...................................6.8g
    Borax ..................................................16.1g
    (Boric acid ..............................................0.62g)*
    Water to.................................................1L

    I think that boric acid can be omitted, because ratio borax-boric acid is 1:25.
     
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  6. Alan Johnson

    Alan Johnson Subscriber

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    Perhaps starting with Parodinal one could make a p-aminophenol analog of Ryuji Suzuki's DS-2 which is a metol based acutance developer with a pH of 9.8.Rainy day project.
     
  7. Relayer

    Relayer Member

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    Alan, strange that p-aminophenol now used only as rodinal/parodinal. I have some old-time formulas with PAP.
     
  8. semi-ambivalent

    semi-ambivalent Subscriber

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    Bored yesterday, I waded through a very long thread about Rodinal where Gainer mentions 11.9 as the pH of either his 'rodinal' or that of the person he was speaking with. I'l try and find the recent thread that links to it.

    s-a
     
  9. semi-ambivalent

    semi-ambivalent Subscriber

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  10. semi-ambivalent

    semi-ambivalent Subscriber

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  11. Alan Johnson

    Alan Johnson Subscriber

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    Relayer, what old time formula is that?
    Michael Gudzinowicz was a good contributor to the old Google groups.

    IMO P-aminophenol has 2 advantages over metol at high pH:
    (1) It does not hydrolyze (react with water), see my 62 year old Azol test:
    http://www.apug.org/forums/forum37/82317-vintage-chemicals.html
    (2) Homebrewers can make it from Tylenol/Paracetamol capsules or caplets, as in PaRodinal.

    Metol has 2 advantages over p-aminophenol at lower pH where it is stable:
    (3) It is sharper.I find acutance in the order FX-1>FX-2>Rodinal=Pyrocat.
    (4) It develops in half the time.I found a D-76d copy made using PAP instead of metol produced similar grain but took about twice as long.

    The structure of Metol and p-aminophenol in solution where they are ionized is similar but Metol has a CH3 group instead of an H group.
    It's possible that this may mean that the Metol is more ionized and reactive but I have not read any comment on this.
     
  12. Relayer

    Relayer Member

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    by example:

    Sodium sulfite 20g
    PAP 3.5g
    Hydroquinone 2.5g
    Sodium carbonate 27g
    Potassium bromide 1g
    Water 1L

    from my books PAP-Q developers produce less fog than M-Q at same pH

    Other interesting combination maybe PAP-Glycin like FX-2