Starting point for bleaching back neg with potassium ferricyanide

Discussion in 'B&W: Film, Paper, Chemistry' started by Akki14, Sep 28, 2007.

  1. Akki14

    Akki14 Member

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    What sort of dilution do I need for bleaching back a negative with just potassium ferricyanide? Will refixing the negative in rapid fix be okay or will it do some harmful/bad reaction?
    I got a box of c.1968 HP3 4x5 sheet film and it has some heavy base fog... after searching around on here I read someone uses potassium ferricyanide to bleach the negative back to counteract base fog but no one ever says how much or a formula or starting point. I'd need enough liquid for a 10x12 tray so about a litre will do.

    Picture of the bad base fog in this thread: http://www.apug.org/forums/forum127/42975-look-what-i-got-today-hp3.html#post525799
     
  2. Ian Grant

    Ian Grant Subscriber

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    I doubt its worth it the fogging looks too bad. Start with a 1% solution of Potassium ferricyanide.

    Then refix when ready.

    Ian