Retouching a varnished photograph

I am working on a very damaged photograph (end of the XIXth century,
gelatino-chloride emulsion). Apparently it has been "restored" a
long time ago, but not in a very conventional way. I guess it was in
a very poor condition, so it was glued to a very thick board, and
the emulsion was varnished, probably because it was very flakened. I
have no idea about the type of varnish used, but it is very smooth
and shiny.

I decided not to dismount it from the board because it is too
fragile to endure this operation. I just want to consolidate the
surface and to retouch the numerous emulsion gaps. But there is a
problem with this varnished surface. I put a first intermediate coat
of methylcellulose with no problem, but now I can't use aquarella
because it doesn't want to stay on this shiny impermeable surface.
I can't either try to remove the varnish because the surface is too
damaged.

Did someone experienced this situation? Which kind of medium or
painting can I try (compatible with photographic material of
course)?

Gwenola Furic
Private photography conservator
4 bis rue de Vincennes
35700 Rennes
France
+33 0 6 64.67 05 22


                                  ***
                  Conservation DistList Instance 18:17
                 Distributed: Thursday, October 7, 2004
                       Message Id: cdl-18-17-033
                                  ***