Ryuji said:
Microfilm and enlarging papers are fairly similar.
There are studies about enlarging papers, duplicating films,
and other materials from various labs, including Eastman
Kodak, RIT, national museum of Denmark, etc.
There are studies. Specifically, I've not seen one concerned
with selenium and FB paper. Never the less, nothing tops sulfide.
The IPI gives reasons for the use of polysulfide rather than
sodium sulfide. None of those reasons has anything to do with
sodium sulfide's effectiveness as an archival treatment. They
do not spell out their reasons for mentioning the polysulfide.
Drum quantities is likely a factor, manufacture, and S&H
are likely others.
They do say that sodium sulfide affords complete archival
protection at a 1:9,999 strength; 0.01%. in solution. Dan