Freezing Methods
Freezing water-damaged materials is an effective method of stabilizing books, manuscripts, maps, etc. until they can be properly dried and treated. Advantages include:
Deters the growth of mold, although it does not kill the mold spores.
Provides time to organize and implement drying operations and to restore the building.
Cold Storage or Home Freezer
Materials are placed in cold storage or freezer at temperatures of at least 14F to 20F or even lower (to -40F). Materials must be frozen as quickly as possible to minimize the formation of large ice crystals.
Blast Freezing
Good for books that are only damp or moderately wet
Materials are placed in a self-defrosting blast freezer, one that freezes very quickly to temperatures below -10 to -40F as soon as possible after the disaster. Materials will dry if left long enough in these conditions, from several weeks to several months. Coated paper will block in this method. Support the bindings of books to prevent swelling.
Vacuum Freeze-Drying
Most effective for large quantities of water-damaged materials.
Materials are placed in a chamber from which air is removed to create a vacuum and carefully controlled heat is applied. As water goes from the ice phase to the vapor phase, heat is lost. The temperature is continually lowered in this way as the water sublimates directly from the ice stage to vapor, much like a frost free refrigerator, thus eliminating further water damage. Care must be taken to ensure that materials are neither under nor over-dried.
Because costs are high, this method is not recommended for small numbers. Since a facility offering this service may also be involved in food processing, there may be problems keeping items separate from food being stored.
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