Freezing wood

Zu-Chun Liao <zchun [at] nmns1__nmns__edu__tw> writes

>I have several artifacts which are infested. They are wood and
>bamboo materials. I am thinking to use freezing method to treat
>them. However, I am a little bit worry about the influence of
>freezing on my artifacts.

For the past 6 or so years I have been routinely freezing many
ethnographic wooden objects, frames and some European objects to
eradicate pests.  I have modified our procedure slightly over that
time but all in all we have had good success with not noticeable
object damage due to this treatment.

We use an old fashioned chest freezer (*not* frost free).  I wrap
the object in plastic making sure to seal all the seams with
tape--If you have time to heat seal the seams that would be even
better.  I try and minimise the volume of air around the object.  I
place in freezer--supported if it is an unstructured object such as
a textile. I turn the freezer on and make sure the temperature drops
quick during the first few hours. Our freezer then maintains -20
degree F quite happily. I keep it like this for one week then I
switch the freezer off. 24 hours later I open the lid slightly and
once the object reached room temperature I take it out.  I have a
digital thermometer which reads inside and outside temperature--I
place a small wire into the freezer under the object to get the
inside temperature and this guides me as to when to remove the
object and to make sure the freezer is reaching a low enough
temperature.

In the conservation literature you will see that this treatment is
not recommended for inlaid furniture but I have treated some masks
with inlay and have experience no problems.

If you have any further questions I can be reached at 415-750-3649

Lesley Bone
Object Conservator
Fine Arts Museums of San Francisco.

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                  Conservation DistList Instance 10:35
                 Distributed: Saturday, October 5, 1996
                       Message Id: cdl-10-35-003
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