Freezing an historic house

Zoe Old <zoe_old<-at->yahoo<.>co<.>uk> writes

>I wouldn't normally consider this, but as the house lacks humidity
>control, has poorly fitting windows and doors, and has only two
>heaters that work, I was considering attempting to freeze the entire
>house one day over the winter, having read a brief article about
>freezing a herbarium in Studies in Conservation (Volume 39, Issue
>Supplement-1).

To freeze things for pests, you would have to keep the temperature
below -20 deg. C for a lot longer than one day.  One day below 0
deg. C would kill the adults but not the eggs, which would just
hatch and re-infest.  To treat for pests, you need to keep
temperatures below -20 deg. C for about two weeks.  With global
warming it is difficult to find weather that remains consistently
below -20 deg.C for that long, even in a Canadian winter, unless you
truly live in the arctic regions.  One sunny day is all it takes and
you have to start the clock again.

Freezing and freeze drying has been trialled in the Canadian winter
(see CCI studies on outdoor freeze drying), but these studies were
done in the 1980s before global warming had progressed as far as it
has now.  The winters of my childhood no longer exist.

The other issue with freezing houses (having actually lived north of
the arctic circle and had to endure power outages) is that you have
to drain the plumbing or the pipes will freeze.  When the house
thaws, you then get a flood and serious water damage.

However, heat treatment is an alternative.  In the 1990s when I
worked for Parks Canada we had to deal with a severely infested
cottage where borer insects were making it structurally unstable.
The cottage was located on the most southerly point in Canada, so
the winters were not severe enough for a good freeze, and it was in
a highly significant bird sanctuary, so pesticides were not
acceptable for use.  One of the options that was considered was heat
treatment.  This is relatively simple because you only need to raise
the internal temperature of all objects to 50 deg. C and 60 deg.C
for an hour to be effective.  To accomplish this, the structure
could be sealed in a plastic bubble (provided it is not enormous in
size), install industrial heaters, and raise the temperature until a
thermal probe in centre of the biggest, densest part of the object
attains a temperature of 50 deg. C+ and maintain it there for a few
hours.  The whole treatment would take a couple of days (it would
take a day or more to bring things up to temperature).  It is
important, however, to monitor and control the humidity during the
process.  Raising the temperature will lower the humidity
sufficiently to cause warping and splitting if you don't control it.
Also it is recommended to check the interior of the house for any
objects or components composed of wax, soft plastic, paints, and
finishes that would melt or soften at these temperatures, or items
that would suffer extreme accelerated aging.  These objects would
have to be removed and treated separately.  Most houses and house
paints will survive +50 deg. C, but the contents may be different.

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 7070ext7304


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                  Conservation DistList Instance 28:32
                 Distributed: Friday, January 16, 2015
                       Message Id: cdl-28-32-002
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