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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.
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.