Storing objects in sealed plastic bags

Eliza McKenna <eliza.mckenna<-at->awm<.>gov<.>au> writes

>I am seeking some advice on storing collection in polyethylene bags.
>We have recently had a clothes moth infestation and had to freeze
>our entire textiles store. ...
>...
>...  For items that are less vulnerable to off-gassing, such
>as textiles, we are interested to see if we can keep these stored in
>plastic for as long as possible, even permanently. ...

These are my thoughts on storing in plastic bags:

If you don't have good environmental controls, it's probably not a
good idea.  A drop in temperature could cause rH increase or even
condensation in the bags, leading to mould and other problems.  You
probably have good controls, so this is less of an issue.

Then there's the issue of offgassing pollutants.  It's not just
nitric acid and sulphur fumes from plastics and rubbers that you
have to worry about.  Organic materials such as wood, paper, plant
materials, including some textiles, offgas organic acids.  This is
why we spend the money on acid free cardboard boxes for storage.  If
you seal these materials in plastic, the artefact itself could
enhance the yellowing and embrittlement of aging by building up
these acids.  And there are varieties of other pollutants, depending
on the object and materials.  Even just building up stinky smells
from smelly objects is not a good idea.

Then there's the fact that some pest species have sharp teeth (well,
mandibles) and a plastic bag is not a significant barrier if it
wants to get in/out.  A bag will deter a casual passer by, but if it
thinks there's something interesting on the other side, an insect
can be through in no time (as anyone who's had ants get into a bag
of bread can attest).

In general, I would not recommend storing in plastic bags
permanently, unless you treated it as a microclimate and had annual
checks on condition, pest ingress, and pollutants monitoring.  This
kind of defeats the purpose, as accessibility is impaired when
things are sealed in plastic, and you have to unpack and repack
everything each time.

Storing in plastic bags temporarily while you get a pest infestation
under control is probably a good thing to do though.

Others may have different thoughts on things, but those are mine.

Hope that helps,

Valerie Tomlinson
Conservator
Auckland War Memorial Museum
Tamaki Paenga Hira
The Domain
Private Bag 92018
Victoria Street West
Auckland 1142
New Zealand
+64 9 306 7070ext 7304


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                  Conservation DistList Instance 29:45
                 Distributed: Saturday, April 16, 2016
                       Message Id: cdl-29-45-002
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