Plastics and condensation

"Breathing" fabrics and "Condensing" plastics- opinions invited.
A number of people have queried me lately about plastic "causing"
condensation (apparently this was mentioned again on a recent Martha
Stewart segment), so I am canvassing the opinions of professional
conservators about fabrics "breathing", and plastic "causing"
condensation.

My own belief is that although some plastic materials can be
dangerous due to off-gassing, condensation is not  usually
exacerbated by plastics. True, I can envision a relatively cool
section of a plastic bag or box promoting local condensation, but I
think this an unusual circumstance. Generally once conditions that
could promote mold growth exist, one will likely have trouble with
or without plastic.

This leads me to the question of whether fabrics "breathe". (I'd
like to put a stake through the heart of this rumour of the undead
as well). It seems to me there is more danger in allowing the
constant intake and evaporation of atmospheric water and gases than
in isolating a fabric from same. My understanding is that pollutants
accumulate in the fibres as it absorbs and releases moisture, and
that the same process also induces mechanical stresses in the
fibres. To stretch a metaphor from biology, the more the fabric
"breathes" the faster it will age.

Of course, I am also aware that usually the usual cures for
breathing are more disruptive than accepting its drawbacks, and I
expect and welcome this response.

Jerry Shiner
Object & Textile Conservation Services Ltd.
Keepsafe Systems and Forever Yours Gown Bridal Preservation


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                  Conservation DistList Instance 14:26
                Distributed: Wednesday, November 8, 2000
                       Message Id: cdl-14-26-004
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