Quote Originally Posted by AgX View Post
...the action of Sistan is often referred to as an `colourless
toning´ with those tiny amounts of silversulfide in mind.
The IPI should chime in now and then. This Sistan discussion
reminds me of one of their findings. Sodium sulfide at a 1:9,999
dilution was found to give microfilm complete protection without
'toning'. In effect Sistan may be no more than a very expensive
drop of sodium sulfide. Dan