Actually, the publication by Tom Strang that John Simmons cited is an
update on the Florian paper and is much more up-to-date as well.

Sally Shelton
Director, Collections Care and Conservation


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|                 San Diego Natural History Museum                      |
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On Tue, 23 Jan 1996, Alice Hoveman wrote:

> The best written information that I am aware of on the freezing technique
> was written by Mary-Lou Florian, Conservation Scientist at the British
> Columbia Provincial Museum. It was published in the Leather Conservation
> News, Volume 3 Number 1 Fall 1986. It is approximately 13 pages long. The
> Leather Conservation News was a bi-annual publication of the Materials
> Conservation Laboratory, Texas Memorial Museum and affiliated with the ICOM
> Committee for Conservation's Working Group: Conservation of Leathercraft
> and Related Objects. The 1986 publication indicates the following address:
> LCN, Materials Conservation Lab, BRC 122, 10100 Burnet Rd., Austin, TX
> 78758 USA.
> I don't know if a copy is available through them or if there is any other
> research or publications on the subject. I do have a copy and may be able
> to send one to those in need of it.
>
> However, the following is extracted from this article, entitled "The
> Freezing Process - Effects on Insects and Artifact Materials"
>
> "Conclusions and a synthesis of the information leads to the following
> procedure recommendations:  Artifacts containing non-absorbent or wet
> materials should not be processed in a constant temperature chest freezer.
>         1.  When using a chest freezer, infested artifacts should be bagged
> in airtight clear polyethylene film, and partially evacuated, the amount
> depending on the stability of the artifacts and its tolerance to the
> pressure of the film against it. When using a controlled temperature and
> humdity freezing chamber, bagging is not necessary. Precautions should be
> taken when bagging infested materials, because as soon as the artifact is
> in the bag, insects will respond to the environmental change and try to
> escape, therefore seal immediately.
>         2.  When using a chest freezer, if the artifact is large (i.e.
> furniture), pretreated silica gel or absorbent materials can be included
> with the artifact in the bag to absorb the excess water due to cooling of
> the air around the artifact and to maintain a relative humidity below 100%.
>         3.  Bagged and infested materaials should be kept at room
> temperature (above 18 degrees C) until placed in the freezer. In an
> emergency, they may be placed in a refrigerator until freezer space is
> available, but should not be temproarily stored in a cold basement or cold
> storage with temperatures above 5 degrees C.
>         4.  There should be adequate air circulation around the artifact to
> allow it to cool to at least 0 degrees C in four hours.
>         5.  Thermo-couples should be used to record the time/temperature
> parameters of the freezing procedure, i.e. the rate of cooling and thawing,
> and the time at the minimum temperature of the artifact.
>         6.      The minimum temperature has been established at -20 degrees C.
>         7.      The time span at the minimum temperature has been
> established at 48 hours.
>         8.      A slow rate of thawing is desirable, i.e. when the rate of
> increase of temperature cannot be controlled, place materials directly from
> the freezer into a refrigerator or cold storage and leave there until
> thawed; or slowly increase the temperature  of the freezer up to 0 degrees
> C over a period of 8 hours (arbitrary).
>         9.      It is desirable to immediately repeat the freeze-thaw cycle.
>         10.     If possible, leave artifacts in the polyethylene bag for
> storage. Do not remove the bag until the artifact has reached room
> temperature and there is no condensed water on the outside of the bag.
> Insect remains should be removed if present.
>         11.     A record of all the above procedures should be made and
> included with the condition report for the artifact. The record should
> include: identification, stages, and activity of the insect; packaging
> materials and method; time required to bring materials to 0 degrees C and
> to minimum temperature; time materials were held at minimum temperature;
> time required to bring materials to room temperature; any physical changes
> observed; and the success of the procedure."
>
> Alice Hoveman, History Curator (and former conservator)
>
> Alice R. Hoveman
> History Curator
> Redding Museum Of Art & History
> P.O. Box 990427
> Redding, CA  96099-0427
> voice: (916) 243-8801
> fax:   (916) 243-8929
> e-mail: [log in to unmask]
> Redding Museum Web Site: http://www.shastalink.k12.ca.us/www/rmah/RMAHmain.htm
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>