From: "Dr. Bruce E. Kahn" <bkahn@mail.isc.rit.edu>
Subject: Hardening gelatin with formaldehyde
Date: Thu, 18 Mar 2004 03:51:02 -0500
> In the conventional AgX photographic world (as opposed to alt),
> formaldehyde hardening caused a number of other problems (other than the
> ones discussed here). It is a reducing agent and can create fog,
Point well taken -- indeed, I mentioned this problem a bit while ago,
but silver gelatin processors are very minority here (I only know a
few) and some people (probably deliberately) misunderstood that the
shortcommings of formaldehyde only applied to AgX processes... so I
purposely avoided this topic. It's not always scientific here...
Plus, at least one person on this list is using commercial liquid
emulsion with formaldehyde hardening because she can't find
glutaraldehyde. She doesn't seem to be annoyed by fogging problem...
it maybe because the liquid emulsion is very slow and also added lots
of stabilizers and antifoggants.
> [...] and can cause afterhardening. This later
> point may be important for those of you here. Basically, it means that you
> can't stop it from doing it's thing. Even when you think that the
> hardening is finished it can actually keep going. Overhardening is
> bad! So if you are interested in doing alt for archival reasons, you
> probably shouldn't use formaldehyde hardening of gelatin.
Related to this point, I also discussed disadvantage of chrome alum
hardeners here, but some people still favor chrome alum over
formaldehyde or glyoxal... and not considering glutaraldehyde. I don't
understand it.
-- Ryuji Suzuki "All the truth in the world adds up to one big lie." (Bob Dylan 2000)Received on Thu Mar 18 06:02:51 2004
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