From: Jack Fulton (jefulton1@home.com)
Date: 09/27/00-10:57:34 AM Z
>> Please, can someone tell me what is the difference between Sodium Bisulfite
>> and Sodium Metabisulfite?Iam about to make a batch of pyro which calls for
>> the former, but I can only find the latter. What should I do?
Sodium Bisulfite (leucogen) if NaHSO3
Sodium Meta-Bisulfite is Na2S2O5
Sodium Sulfite is Na2SO3
The bisulfite can be substituted weight for weight w/POTASSIUM
meta-bisulfite. It is is used removing silver stains from POP, as a clearing
bath in reversal processes and for preserving fixers.
The meta-bisulfite is used as an alkali in photo developers, to hinder or
avoid creation of gas when it comes in contact w/an acid and that lowers the
possibility of blister formation during your processing of film.
Sulfite, as we most likely all know is used as a preservative to prevent
oxidation in developing agents such as metol and Hydroquinone. It is also
used in fixers, as a blackener in neg intensification and as the active
energizer in Amidol developers.
Not being a chemist (Sil can pop in here) but the Sodium Bisulfite can be
substituted one for one w/the the Sodium Metabisulfite.
Jack
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