Bleach Question

Discussion in 'Color: Film, Paper, and Chemistry' started by kb3lms, Dec 6, 2010.

  1. kb3lms

    kb3lms Subscriber

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    Yesterday, I mixed up a 500 ml solution of C-22 style Potassium Ferricyanide bleach using 40g K Ferricyanide and 10g KBr. I then ran a film through it (Gold 200 35mm 24 exp) by developing with some remaining JOBO Press Kit developer as follows:

    Develop: 3 min 30 sec
    Stop: 30 sec
    Wash: 2:00 min
    Bleach: 3:00 min
    Wash: 2:00 min
    Fix: 4:00 min (Flexicolor RA fixer)
    Wash: 5:00 min
    Jobo Stabilizer w/ Photo-Flo added

    Temp through the bleach stage was 102 degrees F, left the water cool after that, ending up about 95 degrees after fixing.

    Ended up with negatives that are about half the density I would expect. The frame numbers and bar codes as well as the exposed part of the leader are also about half the density I would expect.

    Here's the question: Is there any reason to suspect the bleach as the cause of thin negatives? It definitely worked, the negs are just thin but appear normal otherwise.

    The developer is highly suspect because it is getting old AND it left some kind of black crap in the bottom of the tank, although not on the film. The film was also a junk film. Looking at the ages of the kids on the negatives, I would suspect it was exposed 3 or 4 years ago at a beach in the kid's P&S camera and has been sitting in the freezer ever since.

    I plan to purchase some Kodak developer to use in the near future and would like to decide if the bleach is suitable.

    Jason
     
  2. RPC

    RPC Member

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    I would not suspect the bleach as I have used a ferricyanide bleach formula similar to yours and have had no problems. I would double the wash time after the bleach, however, just to mitigate any problems of the bleach reacting with the fixer. A sulfite clearing bath and wash is even better.
     
  3. nworth

    nworth Subscriber

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    The C-22 process worked at 75F rather than the 100F common with the C-41 now in use. That may or may not be a factor here. Bleaching goes to completion as far as the silver is concerned, but an over-active bleach might affect the dyes. For comparison, I dug out the SR-29 formula used with the ECN-2 motion picture process. ECN-2 is not C-41, but it also works at 100F and the bleach is probably similar.

    Alternate Bleach (Kodak SR-29)
    Water 900 ml
    Potassium ferricyanide (anhydrous) 40 g
    Sodium bromide 25 g
    Water to make 1 l
    pH 6.5, density 1.037
    Time 3 minutes
     
  4. hrst

    hrst Member

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    I've read quite a bit of ECN-2 documentation as I'm building an MP lab.

    ECN-2 documentation does not mention anything about sulfite clearing bath that has been discussed here.

    BUT, ECN-2 uses sulfuric acid as a stop bath (documentation does not give any alternatives); a twist I've never seen discussed here. Could it have the clearing action comparable to sulfite clearing bath?

    Of course, good wash between stop bath and ferricyanide bleach is suggested.
     
  5. georgegrosu

    georgegrosu Member

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    Following chromogen developer is formed metallic silver and dyes.
    In the bleaching phase, the silver is transformed into a complex combination, which deleted in the fixer phase of the film.
    In my opinion, partial destruction of the dyes can be made only by drying the film at an acid pH. We proceed to weaken/correction for color prints that came out darker.
    In your case, I think it is a rather under development.
    If you had problems with color developer then you'll get a higher fog.
    Old films give a great fog.
    George
     
  6. RPC

    RPC Member

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    PE has talked about it; but I'm guessing it may not be necessary depending on the actual process involved or with adequate wash times.
     
  7. Mike Wilde

    Mike Wilde Member

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    I usually c-22 bleach just like this: I find it is done after 2:30, but an extra :30 never hurt.

    You developer is weak; this is what gave you the weak image.

    Try more concentrate per littre is yiou feel like experimenting. I would not recommend longer that 3:15 or off of 100F with c-41 to compensate for weak developer. I have done adjusted time for temps a bit hot or cold, but not the best idea.

    The better solution is fresh developer.
     
  8. georgegrosu

    georgegrosu Member

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    Mike Wilde
    A new developer is always a good idea.
    If the density of the fog is not increased, in my opinion, is a indication that there are not problems with developer.
    George