Freezing composite objects Freezing botanical specimens

There were two queries on freezing the in the last posting
(Conservation DistList Instance: 18:33 Sunday, January 23, 2005),
one concerning freezing of botanical specimens and the other
concerning freezing of composite objects. Since my MA dissertation
in conservation had been on this very subject, I'd like to report
that freezing composite objects did not seem to have any adverse
effects--even when the objects were composed of considerably
different and/or complex layers (gilded and painted wood, objects
studded with inorganic substances etc.). Papyrus, which is very
brittle when old, did not exhibit any change or damage following
freezing.

What can be said, in reinforcement to Vicky Purewal's note, is that
old and brittle adhesives *might* be at some risk--although none of
the specimens I tested showed any adhesive-related change due to
freezing, even when inspected through FTIR, SEM and optical
microscopy. Although there definitely is room for more research to
be made, freezing appears to be a relatively safe method. Of course,
it is a method that should be performed correctly: objects should be
enclosed in close-fitting polythene bags to prevent ice formation
and condensation.

Gali Beiner
Conservator
Pitt-Rivers Museum, Oxford


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                  Conservation DistList Instance 18:36
                 Distributed: Sunday, January 30, 2005
                       Message Id: cdl-18-36-006
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