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Subject: Freezing botanical specimens

Freezing botanical specimens

From: Vicky Purewal <vicky.purewal<-a>
Date: Monday, January 24, 2005
Dee Stubbs <dstubbs [at] nb__aibn__com> writes

>... To date, our botany/herbaria specimens have not usually
>been frozen and that department has asked for reassurance that the
>process is safe.
>Our normal procedure for incoming material is to seal the artifact
>or specimen in an airtight bag, freeze for one week, defrost in the
>unopened bag for several days and then refreeze for a second week. ...

The National Museums and Galleries of Wales have been freezing
specimens for decades and have found no adverse affects. The NMGW
collection are mounted by gelatine backed linen tape and this is an
important consideration when freezing as some specimens that have
been glued can be damaged through repeat procedures and delicate
flowers have been seen to split and break. If the bags are sealed
properly before freezing then the RH fluctuations will be greatly
reduced, but there will still be some stress between the mount
sheet, the specimen and the method of securing that specimen.

Victoria Purewal
Department of Biodiversity and Systematic Biology
National Museum and Gallery of Wales
Cathays Park
Cardiff CF10 3NP

                  Conservation DistList Instance 18:34
                 Distributed: Tuesday, January 25, 2005
                       Message Id: cdl-18-34-004
Received on Monday, 24 January, 2005

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