Anoxia and plastics

Valerie Tomlinson raised some interesting questions and ideas when
commenting on Ingrid Neuman's posting (Conservation DistList
Instance: 25:5 Tuesday, July 5, 2011),

While it seems "common sense" that darkness, cold temperatures and
lack of oxygen will slow down deterioration of plastics, it is wise
to keep in mind that we are often surprised by what happens in
extreme conditions. This has been demonstrated in recent studies of
the effect of anoxia on pigments and substrates (studied at the Tate
and elsewhere). So given the caveat that it may or may not be the
best solution, I can pass on some ideas for how to effectively
create anoxic conditions.

Any package used to create (and maintain) very low oxygen levels
will need to be made of an efficient barrier film. One such film is
Escal, which is a transparent high gas barrier film. Marvelseal is
another multilayer film using a layer of aluminum foil to provide a
gas barrier. Mylar (polyester) film is not a gas barrier film,
although it may be used as a structural component in a multilayer
film. Also bear in mind that a barrier film encapsulation / bag must
be properly heat sealed.

Ageless does release some moisture and heat as it absorbs oxygen. In
most applications (usually at room temperature and when used to
store or treat organic materials), the heat is quickly dissipated
and the released moisture is absorbed by the artifacts sealed in the
bags, creating only a short-lived spike in humidity. Using only the
necessary quantity of Ageless will reduce this effect.

An alternative to Ageless is RP system. RP-K system is moisture
neutral, and does not release moisture as it absorbs oxygen. RP-A
system absorbs both moisture and oxygen, providing a very dry anoxic
environment. Both kinds of RP also absorb and bind a wide range of
gaseous pollutants.

More information on these products is on

    <URL:http://www.keepsafe.ca>

Jerry Shiner
Keepsafe Microclimate Systems
800-683-4696


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                  Conservation DistList Instance 25:8
                   Distributed: Monday, July 25, 2011
                        Message Id: cdl-25-8-004
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