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3. Stabilization by freezing

The most effective method found to date, and the most generally accepted by conservators for the stabilization of water-damaged archival and library materials is freezing at low temperatures. A level of about -30 C (-20 F) is recommended; the frozen materials remain in cold storage. Quick freezing, such as the so-called blast freezing, is a method used to produce the formation of the smallest ice crystals possible. Slow freezing produces large, needlelike crystals.

3.1 Advantages

3.1.1 Halts mold attack

Without the conditions required for the reproduction and development of the spores, mold infection ceases upon freezing. True, the mold spores are not destroyed by freezing; they remain in a dormant state until a more favorable environment is available. But the fact remains that the infection is effectively checked and its pernicious damage cannot take place.

3.1.2 Stabilizes soluble inks and dyes

Freezing has the additional advantage of stabilizing inks, dyes, dyestuffs, colorants, etc. used for manuscripts, maps, sketches, drawings, and such, that are soluble in water. Later, when freeze-drying takes place, migration or feathering of inks or dyes can be restrained since the liquid stage is by-passed.

3.1.3 Prevents adhesion of leaves

The problem of blocking or adhesion of leaves to each other is primarily confined to books and periodicals printed on stock that uses a coating pigment with a binder of casein and starch, two highly water-soluble substances. If wetted material of coated stock is permitted to dry it will turn a book to a clay-like brick. Restoration is impossible. At the moment the only known salvage method considered practical, especially where large quantities of water-damaged material are involved, is freezing whilewet then freeze-drying.

3.1.4 Permits orderly, unhurried planning

The freeze stabilization of water-damaged archival and library materials lifts a tremendous load from the shoulders of those who have suffered a disaster. Stabilization permits time to confer with experts on the selection of drying methods. There is time to assess damage, to see what can be discarded, replaced, microfilmed; time to determine what repairs or restoration might be required; time to rehabilitate a damaged storage area, or to find an alternate location.


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