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  1. #1

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    Alkaline fixers and hardening

    Lately there has been a fair amount of discussion about the problems involving processing films with soft emulsions with non-hardening alkaline fixers. Alkaline fixers have some distinct advantages when it comes to washing, but the soft films scratch easily. In the past I have recommended using E-6 stabilizer (the formalin based variety) after washing, but E-6 stabilizer contains only a half to a quarter of the formalin per liter that formalin hardeners have. It may or may not be effective.

    The reason for a thorough wash is to get rid of the silver complexes left after fixing. As the fixer is used more, this becomes more difficult. These complexes can lead to image deterioration with age. The complexes are harder to wash out at low pH, so alkaline fixers make the wash step easier and more effective. But hardeners can only be incorporated into acid fixers. We would like to have both easy and effective washing and hardening.

    It can be done, if you harden the films after washing. Just fix in the alkaline fixer and wash as usual, then harden the films in one of the standard hardeners. If you have formalin available, Kodak SH-1 or SH-6a are attractive. For more usual work, Kodak F-5a or F-53 are typical. These hardeners last a very long time, so they are quite economical. For high temperatures you can also use a solution of 30 grams per liter of potassium chrome alum, although this will deteriorate in time. There is no free lunch, however. You now need to wash out the hardener. But hardeners are easy to remove, and residual aluminum is far less dangerous than residual silver. Several water rinses will do, and the Ilford wash procedure should be more than adequate.

  2. #2
    Leigh B's Avatar
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    If you use a fixer neutralizer like Hypo Clearing Agent or Perma-Wash you eliminate the residual fixer problem and dramatically reduce the wash time.

    As PE says, scratches are eliminated by handling the film carefully during processing, not by anything done afterward.

    - Leigh
    Last edited by Leigh B; 09-04-2011 at 06:27 PM. Click to view previous post history.
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  3. #3
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    There are some important points that are missed here:

    1. When using soft films, then hardening after the process is complete is usually too late to do any good. Scratches are put on in the process steps. You need a hard film, or you need to pre-harden.

    2. Ammonium fixers cannot be mixed with formalin in a single bath. They must be separated by a wash in between. Formalin should not contact Sulfite solutions. There should be a wash in between.

    3. Harding very swollen film (or paper) does not give very good hardening. You must inhibit or remove the swell by some means, usually adjusting pH to about 4.5 or by using an antiswelling agent such as Sodium Sulfate (ATE not ITE) at a very high level.

    4. Any Alum hardening can be reversed leading to soft film or paper.

    etc. etc.. etc......

    PE



 

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