Silica gel

Barry Knight <barry [at] eng-h__gov__uk> writes

>Clara Margaret Deck <deck [at] umd__umich__edu> writes
>
>>I would like to hear from anyone who has worked with silica gel as a
>>buffering agent for sealed exhibit cases. More specifically, I would
>>like to know what ratio of silica gel-to- case volume has proven
>>effective in maintaining a reasonable RH range over time (say, three
>>months).
>...
>It is important to line the case with a single sheet of Moistop,
>carefully folding the corners and bringing the edges up and over the
>rim of the case.  It's rather like wrapping a parcel from the
>inside!  We stuck self-adhesive EPDM weatherstrip around the top of
>the case, and sealed the glass into the lid with clear silicone
>sealant.  We concealed the silica gel under a Correx baseboard, and
>placed an ACR datalogger inside to record the conditions.

It's important to be aware that standard silicone sealants out gas
acetic acid as they cure.  Standard silicone sealants should only be
used in a sealed case if the sealant is allowed to cure for several
days to a couple of weeks.  A better bet is a "neutral cure"
silicone.  These are available through major glazing supply houses
such as C. R. Lawrence. Check with your local glass shop.

George Cannon
Preparator
Herbert F. Johnson Museum of Art
Cornell University
Ithaca, NY 14853
607-254-4617

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                  Conservation DistList Instance 10:32
                Distributed: Friday, September 27, 1996
                       Message Id: cdl-10-32-004
                                  ***