I recently mixed up my first batch of silver bromide emulsion using the
instructions Peter Marshall posted on the 28th May this year. I coated the
glass plates a bit too thickly, and because I didn't use the collotype
substratum instructions Bernie Boudereau posted on the 2nd August (I don't
have any sodium silicate - is it worth asking at the Chinese grocery store
for "egg keep"?) had the emulsion sloughing off in the developer. I then
changed to a less harsh developer and used a *hardening* stop bath: 2%
potash alum; 1% each of sodium sulphite and acetic acid. I also threw some
potash alum in the fixer, where the plates took forever to clear. The
emulsion was still a bit fragile, but with care stayed attached.
I got the hardening stop bath recipe from an article on hardening in the old
edition of the Focal Encyclopedia. It's probably also worth reading up on
what they have to say on tropical and high temperature processing. I didn't
have any chrome alum or sodium sulphate on hand so I didn't try any of their
other suggestions.
Who wants to order T-Max glass plates from Kodak when you can mix your own?
The results, however, were not up to Kodak standards, but were acceptable
for a first try.
Philip Jackson