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 ------------------------------------------------------------------------- | | | San Diego Natural History Museum | | P. O. Box 1390 | | San Diego, California 92112 USA | | phone (619) 232-3821; FAX (619) 232-0248 | | email [log in to unmask] | | | ------------------------------------------------------------------------- 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 l >