Glassine envelopes for storing photographic materials

Giovanna Di Pietro <dipietro [at] foto__chemie__unibas__ch> writes

>... We have noticed in the literature a
>general strong recommendation against the use of glassine envelopes,
>related to their chemical quality or to their hygroscopic
>properties. Recently we had controversial experiences. While Daniel
>Oggenfuss (diploma work at the Conservation Program, Bern) showed
>that cyanotypes stored in glassine envelopes undergo a smaller
>discoloration (both in the blue and in the paper) than in other
>types of envelopes...

Your description of the problem is not very clear. It would be
useful to know whether you are talking about 19th century cyanotypes
or contemporary prints kept for a few months or years in glassine
materials.

It has long been recognized that cyanotypes retain their bright blue
color when kept in an acidic environment. This is probably the
reason why the cyanotypes kept in glassine envelopes seem brighter
than the ones kept in other types of envelopes which may not be
quite as acidic. You should avoid using buffered/alkaline storage
enclosures for cyanotypes. They are also relatively sensitive to
light, which tends to bleach them although the process is usually
reversible. Contact me directly for more discussion on this.

Luis Nadeau
Fredericton, New Brunswick, Canada

                                  ***
                  Conservation DistList Instance 11:64
                 Distributed: Tuesday, January 27, 1998
                       Message Id: cdl-11-64-002
                                  ***