Glass plate negatives

I recently came across a group of about 20 severely deteriorated
gelatin/glass plate negatives. The emulsions in these plates are
breaking into small pieces and detaching themselves from the glass
plate. From the different conditions of the negatives it appears to
start in one point and to spread over the whole plate.  The glass
plates don't present any chemical deterioration but they have a
varnish that can be causing this problem.

The emulsions are so fragile that even removing the negatives from
the enclosures causes further damage. The only solution I can think
of is the consolidation of the emulsion.

I would like to know if anyone had the same problem and, if so, how
was it solved. I would also appreciate any suggestions on treatments
and bibliography.

Patricia Marinho Falcao
Photographic conservator



                                  ***
                  Conservation DistList Instance 14:49
                  Distributed: Friday, March 23, 2001
                       Message Id: cdl-14-49-020
                                  ***