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Chris, You might also want to read the Canadian literature on storage. Stefan Michalski’s Guidelines for Humidity and Temperature Control in Canadian Archives (Tech. Bull. 23, Ottawa, 2000) indicates that colder, drier conditions show improvements for media low to medium stability until you get below freezing. Very cold storage, relative humidity becomes virtually insignificant. His figures show at 0 degrees Centigrade, low-stability records are calculated to last 1200-4000 years at 30%RH and 240-800 years at 50% RH. At -20 degrees below 0 Centigrade, there is virtually no impact from RH. Michalski’s work does indicate that you can seriously damage materials by taking them out of cold storage fairly several days in the year. If the materials are going to be used, they should be stored at higher temperatures.
As I explore the topic further, it has become very apparent that the local climate has a tremendous influence on how one should use the published environmental guidelines. In a dry climate like Colorado’s, I have begun to work toward much drier conditions for housing the collections. In this climate, the maximum RH I want is 25%. Conversations with Bill Lull indicate that we should be able to achieve this through with dew point controls on the HVAC system. Engineers might want to discuss this will Bill Lull.
I’d recommend you take a look at Michalski’s work and the Canadian Council of Archives Basic Conservation of Archival Materials: Revised Edition, 2003, Chapter 3 on the Environment, which is available in PDF. Randy Silverman is also a very good local resource on this topic.
Pat Morris Patricia Morris From: owner-padg@xxxxxxx [mailto:owner-padg@xxxxxxx] On Behalf Of Chris
McAfee
Please excuse the cross-posting.
As some of you know, the Church of Jesus Christ of Latter Day Saints is building a new archives/library/preservation building. We want to build our "vaults" to the highest standard possible. We are currently working under the idea that we will have an area with -4 degree F cold storage for our most valuable items (see http://www.wilhelm-research.com/). However, our building engineers are concerned with problems of maintaining proper humidity levels, keeping frost out, etc.
As we've consulted with other archives who have cold storage, their building engineers have expressed concern with our desire to have -4 degree storage and this has "frightened" our own building engineers. Of course, none of these individuals have any cold storage less than 25 degrees and they have not dealt with anything colder. So I have 3 requests:
First: I want to know (from a conservator's or preservation administrator's point of view) how the physical rules change once you drop below 0 degrees.
Second: As most of the facilities we've talked to are also in more humid areas, I also want to know how the physical rules change in a dry climate like Utah.
Third: If those of you who deal with cold storage (35 degrees F and lower) on a regular basis, could make general comments on problems and solutions you've experienced, it would be greatly appreciated.
Thank you, Christopher McAfee
Christopher McAfee ------------------------------------------------------------------------------ |