Potting mix

David Stevenson <dstevenson<-a t->cca< . >qc< . >ca> writes

>In the next couple of months, we will be mounting an exhibit in
>which it is proposed to include a large wooden sculpture/model that
>is to be situated adjacent to a large pile (approximately 3 feet x 2
>feet x 2 feet) of a soil-like potting mix containing: "a blend of
>natural aged fir bark, aged redwood, aged chicken manure, earthworm
>castings, bat guano and kelp meal".  This has been previously
>exhibited elsewhere, in an almost-sealed Plexiglas case (apparently
>the case was more for curatorial than conservation reasons).
>
>...  I will press for
>a sealed Plexiglas case surrounding the dirt ...

Our procedure for bringing potentially infested organic materials in
to the museum are:

    Have a quarantine area for arriving material to be bagged and
    prepared for freezing.

    Freeze at -30 deg. C for one week, followed by two weeks at room
    temperature (still bagged), followed by a final week of
    freezing.  After 24 hours to acclimatize to room temperature
    again, the object is unbagged, and can then be inspected and
    prepared as necessary.

    The museum has a regular pest monitoring procedure with sticky
    traps and other pest monitoring devices.  In this case I would
    add additional pest monitoring traps in the vicinity of the
    display and check that pest levels were not increasing.

My experience with display cases is that they are not a barrier to
insect pests, unless they are sealed so well that an anoxic
environment can be maintained inside.

In the winter months, the risk of pest infestation should be minimal
if this procedure is followed.  In the summer months, the risks
would depend on how good your IPM protocols are at restricting entry
of pests from the outside.  The treatment should render the material
sterile, but it is still food for any pests getting in, so could be
re-infested if anything can make it past your defences.

Alternatively, one could spray toxic pesticides all over the
material, and there would be residual protection against pests that
would last for several months.  However, when it comes to museum
objects, pesticides are considered a last resort these days.

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 27:35
                  Distributed: Tuesday, March 18, 2014
                       Message Id: cdl-27-35-005
                                  ***