SPI-Chem™ Sodium Sulfite Anhydrous
Instructions for use in the clearing of Polaroid Type 55 P/N negatives
Why the need for sodium sulfite at all:
After developing the exposed film for the recommended period of time, the
positive, negative, and backing papers are separated, and the negative
should be immediately immersed in the prescribed 18% sodium sulfite in
water. Gentle and steady agitation is important, as the negative "clears",
that is, the brown developing "jelly", dissolves away from the substrate
plastic. We consider it wise to sort of "fish out" or even decant out
the remains of the developing jelly that end up floating on the liquid
surface.
Processing the reusable negative:
In order to remove the reagent layer and the anti-halation dyes, the
processed negative needs to be washed in an 18% sodium sulfite solution.
The salts within the solution minimize the swelling in the negative's
gelatin layer that would be caused by washing in water only. Swelling can
cause reticulation which would remain after the negative dries.
To minimize (maybe even prevent) scratches:
Negative scratch resistance can be improved by treating the processed
negative(after clearing in water and sodium sulfite anhydrous)
in a solution of Kodak Rapid Fix with Hardener (parts A&B) for two minutes.
This solution should be made up and used in accordance with Kodak's
recommended mix procedures, chemical caution statements, wash times
and temperatures.
We also recommend that the final water rinse before drying, contain
Kodak Photo-Flo®
to minimize or eliminate drying streaks.
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Tuesday October 07, 2008
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