Richard Knoppow wrote:
"Stephan Goldstein" wrote in message
...
I'd like to start playing around with Type 55 P/N film.
From reading I know
the negatives should be cleared (per Polaroid) in an 18%
solution of Sodium
Sulfite. What I don't know is the storage life of said
solution, or how to tell
when it's dead. Or is it immortal?

Thanks all!

Steve

Its tough to answer this because the life of the solution
depends on the concentration of the solution and how much
air its exposed to. 18% is a fairly strong solution, about
what is found in stock Kodak Hypo Clearing Agent. Sodium
sulfite will slowly change to Sodium sulfate by absorption
of Oxygen from the air. In a closed container it will last
for a couple of months, maybe longer. In a tray for several
hours.
Sodium sulfate will do no harm but I don't know if it
functions as a clearing agent for Polaroid.


Note that different emulsions of Polaroid call for different compositions of
that clearing bath. You might look in Ansel Adams' book, "Polaroid Land
Photography", Appendix C, for different formulae for different types.

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