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Subject: Microwave fumigation

Microwave fumigation

From: Niccolo Caldararo <caldararo<-a>
Date: Sunday, February 27, 2005
Sebastian Georgiew <sebastian [at] students__lincoln__ac__uk>

>I am currently researching the possibility to use microwave heat as
>a way to eradicate insects in wooden objects.

It would be interesting to hear from archivists on this point as I
have heard from a number of them over the years since the
publication of articles like the Jerome Brezner and Philip Luner one
in Library Journal (Sept, 15, 1989) that the use of microwaves has
been very successful in reducing infestation of collections. Anyone
know of a study which supports this idea?

The problems posed by the use of microwaves is clearly reflected in
some reports of the affects of too much power and the association of
book boards of wood and some pressed boards and synthetic adhesives
and coatings on binding cloth.  I've also been told that some
devices placed in books for electronic checkout technology can fry
microwave machines.

On the issue of wood and microwaves, I would say this is a very
questionable application unless you  have a fairly heavy duty
machine.  Some machines stop functioning if smoke is detected others
are completely inactivated by nearly any flame-up.  One has to keep
in mind that the idea of killing bugs has to be balanced with the
potential damage to the object.  Almost any microwave device will
heat wood significantly.  The moisture content of the wood will be a
factor both in the potential damage and the effective treatment for
bugs.  Bugs have moisture, polar rotation producing heat will be the
effective agency, but the wood will respond to the activity of the
moisture and the heat generated.  One must clean the interior of a
microwave frequently as flammable substances will collect on the
walls and baffles.  If these build up a flame-up could result.  Also
one must be sure there are no wax or resin fills or metal inserts in
the wood as these will produce conditions for a flame-up and fire. I
know this from experience too, since I destroyed two machines in the
past, once trying to understand the affects of heat on Masonite and
once studying the affects of microwaves on wheat starch paste. In
other words, I am saying that one needs significant experience to
use a microwave for this purpose, one must know the object
intimately and one must have the kind of equipment necessary for the
job and maintain it properly. It should also be a last resort.  The
same can be said for freezing although we now have a few good
studies of the effects of freezing objects.  None of the methods for
killing insects are perfect, once radiation was championed until it
was realized that it made some objects radioactive due to certain
components.  Keep in mind too that all microwave machines leak
microwaves, even new ones.  Get a microwave detector and test since
you cannot put something in a microwave and simply walk away like
you are heating a meal.  It must be watched and you must be ready to
stop the machine.

Niccolo Caldararo
Director and Chief Conservator
Conservation Art Service

                  Conservation DistList Instance 18:41
                  Distributed: Tuesday, March 8, 2005
                       Message Id: cdl-18-41-003
Received on Sunday, 27 February, 2005

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