pyrocat hd - potassium bromide

Discussion in 'B&W: Film, Paper, Chemistry' started by el wacho, Sep 9, 2008.

  1. el wacho

    el wacho Member

    Messages:
    445
    Joined:
    May 12, 2007
    Location:
    central anat
    Shooter:
    Medium Format
    hi,

    am i right in thinking that the pot. bromide in pyrocat hd is not relevant if you are replacing the phenidone with metol? that it is only there to prevent fog from the phenidone-carbonate combination? and by diminishing the level of metol, does one increase the stain?


    thanks.
     
  2. Tom Hoskinson

    Tom Hoskinson Member

    Messages:
    3,879
    Joined:
    Mar 7, 2004
    Location:
    Southern Cal
    Shooter:
    Multi Format
    I have mixed and used Pyrocat-HD with and without KBr and could not see or measure (via transmission densitometry) any difference in my negs.

    The Pyrocat-MC formula does not contain KBr.

    The primary staining component in Pyrocat-MC is the Catechol (same as Pyrocat-HD).

    I doubt that reducing the amount of metol in Pyrocat-MC would reduce the amount of stain. The amount of metol in Pyrocat MC is already small (2.5 grams metol).

    If you added Sulfite to the formula, that should reduce the amount of stain (if that's what you're after??).
     
    Last edited by a moderator: Sep 9, 2008
  3. el wacho

    el wacho Member

    Messages:
    445
    Joined:
    May 12, 2007
    Location:
    central anat
    Shooter:
    Medium Format
    ... no, i was curious if it would increase the stain. thanks for the above.
     
  4. john_s

    john_s Member

    Messages:
    1,094
    Joined:
    Nov 19, 2002
    Location:
    Melbourne, A
    Shooter:
    Medium Format
    I think that Sandy King has said here in APUG that the bromide can be left out of all the Pyrocat family of developers. Do a search, though, in case there is a need for bromide in special cases (about which I might have forgotten).