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Subject: Storage of unstable glass

Storage of unstable glass

From: Stephen Koob <koobsp>
Date: Friday, May 24, 2002
Margrit Reuss <marreuss [at] yahoo__com> writes

>Working as a group of freelance conservators we have been surveying
>a glass bead collection from Papua New Guinea, belonging to a museum
>in the Netherlands. Most of the glass beads on necklaces within the
>collection show crizzling and cracks typical of unstable, degrading
>glass. We intend to improve the lifetime of these objects by storing
>them at around 42% RH. To achieve these conditions we want to use an
>acclimatized storage cupboard which makes use of pre-conditioned
>Artsorb packages.

42% relative humidity is a good set point for your storage of
crizzled glass. You can probably add a plus/minus 2% to that,
without any worry, but you should be careful not to drop much below
40%, i.e., not "overcondition" your Artsorb.

We have two complete cases in our Study Gallery (within the main
Galleries) dedicated to crizzled glasses. Both because of the
location, and our careful monitoring and maintenance of the overall
Museum conditions we do not have silica gel in any of cases. The
humidity tracks almost a straight line in the crizzled cases, with
no more than a 5% drift between summer and winter (40-45%).  All the
cases have silica gel compartments at the bottom, but instead of
silica gel, I have installed a fan in these compartments, which
gives air circulation throughout the case.  In my opinion, this is
also an important measure in preventing crizzling. Even if you use
Artsorb, I would recommend a fan for air circulation.

Because your Galleries are around 50% humidity, I would not be too
concerned about opening the cases for short periods.  You should
recommend that the cases not be opened, should the humidity in the
Galleries be above 55%.

Stephen Koob
The Corning Museum of Glass
One Corning Glass Center
Corning, NY 14830
Fax: 607-974-8470

                  Conservation DistList Instance 15:80
                   Distributed: Friday, May 24, 2002
                       Message Id: cdl-15-80-003
Received on Friday, 24 May, 2002

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