Storing plastic

Colin Williamson <smileplas [at] aol__com> writes

>We have several hundred plastic tokens dating from about 1900 to
>1985. Typically these are transport, credit, shop or advertising
>tokens about 25mm diameter and 2-3mm thick. They are variously made
>from vulcanite, cellulose nitrate (celluloid), cellulose acetate,
>urea-formaldehyde thermosetting material, or polystyrene. ...
> ...
> ... Does anyone have any
>recommendations for an alternative storage solution whilst retaining
>visual access to both sides of the tokens?

I recommend storing the tokens in an oxygen free system such as the
RP System by Mitsubishi. The process that most adversely affects the
plastics and rubbers is oxidation. By removing the oxygen you can
prevent the formation of acid which ultimately causes the demise of
the rubber or plastic. Each token can be placed in polyethylene bags
to separate them and then ESCAL bags (a high gas barrier bag that is
specially designed for oxygen free systems) can be used to group
them together. While the ESCAL bags are clear, it is best to reduce
the amount of exposure to light. We chose not to use oxygen
indicators with our system as they have a short shelf life and are
somewhat inaccurate. The system is actually quite economical and
their website is informative:

    <URL:http://www.mgc-a.com/rpsystem/mgca.html>

Susanne Grieve
Conservator
The Mariners' Museum


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                  Conservation DistList Instance 20:31
                Distributed: Saturday, December 9, 2006
                       Message Id: cdl-20-31-008
                                  ***