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  1. #11

    Join Date
    Nov 2004
    Posts
    1,178
    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/forum37/8...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.

  2. #12

    Join Date
    Jun 2009
    Location
    Odessa, UA
    Shooter
    35mm
    Posts
    234
    Quote Originally Posted by Alan Johnson View Post
    Relayer, what old time formula is that?
    by example:

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

    Quote Originally Posted by Alan Johnson View Post
    IMO P-aminophenol has 2 advantages over metol at high pH:
    from my books PAP-Q developers produce less fog than M-Q at same pH

    Other interesting combination maybe PAP-Glycin like FX-2

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