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10. Other vacuum and freeze-drying activities

10.1 A selection by countries

The use of freezing as a method of stabilizing water-damaged archival and library materials, followed by vacuum-drying or freeze-drying, is gaining more and more acceptance internationally. The purpose of the following country-by-country sampling is to give the reader an idea to what extent this is true.

10.1.1 Austria

April 1985. At the Institute for Restoration, Austrian National Library, Vienna, freeze-drying techniques have been carried out in an old, non-controllable installation where water-soaked books are placed for drying. The process takes more than four weeks. However, there are plans underway to install a modern freeze-drying chamber which will dry such materials in about three days. The chamber will also be used to size and strengthen newspapers; bound newspapers will be impregnated with a solution that strengthens and deacidifies (38).

10.1.2 Canada

February 1977. On February 11th, the building that houses the Engineering Library at the University of Toronto was destroyed by fire. Water was poured into the building for over seven hours. The cold weather produced one benefit: the water-soaked books were quickly frozen and stabilized. Some 500 of these books, considered rare or difficult to replace, were put in the high altitude chambers of the Canadian Forces Base at Downsview, Ontario, in accordance with the University's Disaster Contingency Plan (39).

10.1.3 England

During 1981. A scientist of the Lord Rank Centre for Research, High Wycombe, and a conservator from the Bodleian Library were discussing accelerated freeze-drying used to preserve foodstuffs. They agreed that the process could be used to dry water-damaged books. When Lord Vernon's collection of valuable 16th and 17th century books at Sudbury Hall, Derby, was damaged by a flood a number was taken to the Centre, quickly frozen, and the ice sublimed away in high vacuum. There was no damage to paper or bindings (40).

Reported in 1985. A.P. Bush (41), Archive Conservation Section; National-Maritime Museum, reports an experiment in freeze-drying books in a commercial freezer (non-vacuum technique). A set of nearly identical books (wove paper, case bound, cloth, strawboards) was soaked in water and placed in a commercial cold storage facility. Eight of the books were soaked for 18 hours, taking up to about 50 percent of their dry weight in water. Seven were frozen at -25 C (-13 F). After 16 weeks three books which had been wrapped in plastic film lost two percent of their water; three which had been stacked together and wrapped in paper lost 33 percent; one book wrapped in paper and placed separately for maximum exposure lost 75 percent of its water. After 51 weeks the books were removed; none was totally dry. The books not wrapped in plastic had lost about 81 percent of their water.

10.1.4 France

Reported in 1985. In 1981 a petroleum platform, the Alexander Kielland, sank in the North Sea. Three years later, the platform was put afloat and numerous salvaged documents were put in plastic bags and frozen at -20 C (-4 F). The documents, which hopefully would supply clues to the cause of the disaster, were varied. Most were like solid blocks when recovered and included books, photocopies, paper registers, and carbon paper. The texts were either printed, written in ink, pencil or ball-point pen. The frozen materials were taken to USIFROID, Maurepas, France, where a vacuum chamber sublimated the ice through an elevated temperature. The materials recovered their flexibility satisfactorily; the centers of the books were in a perfect state of conservation. The colored inks on the rolls of register paper had not degraded despite their degree of solubility; pencil notes on paper were perfectly preserved (42).

10.1.5 Germany (FRG)

Reported in 1972. Eichhorn (43) reports the use of "deep freezing" for the stabilization of soaked books. After a flood in Stuttgart that damaged thousands of books stored in library cellars, the materials were placed in industrial cold storage for freezing.

Reported in 1973. Elmer (26) describes the freeze-drying of Neolithic textiles and braided work. These artifacts were first thoroughly cleaned and desalinated, they dried in a vacuum of 1 to 0.5 torr at temperatures of-17 to -24 C (1.4 to -11.2 F).

Reported in 1973. Eichhorn (44) writes on the use of deep freezing for the storage of water-soaked books. These are stored at -20 to -30 C (-4 to -22 F). The intention is to thaw them slowly until dry. Eichhorn notes that it is possible to dry books in the frozen state with a vacuum chamber.

Reported in 1976. The Institute of Space Simulation, Federal Center for Aeronautic and Astronomic Investigation and Testing (Colognes) has found that space chambers can be used successfully in recovering books, manuscripts and documents which have suffered deterioration as a result of high environmental humidity, broken pipes, or floods. Small chambers are best in which the principle of physics is used where water evaporates with greater speed as the pressure is reduced. A temperature of 50 C (122 F) is maintained in the chamber while the interior pressure is kept at 5 and 10 mm Hg by the vacuum pumps. The extracted humidity is transformed into ice on special freezers. In experiments carried out with wetted paper, its dehumidification takes from 20 to 40 hours depending on the quantity. Deterioration is minimal. Wet books with pages stuck together can be used without difficulty at the end of 24 hours. The cost of running a thermal vacuum chamber with a volume of three cubic meters (106 cubic feet) for 24 hours is 300 marks. A smaller chamber with a volume of one cubic foot (0.028 cubic meters), into which 250 kilograms (551 pounds) of paper can be placed for treatment, costs one half the amount (45).

Reported in 1985. In January 1985 the University Library at Wurzburn, Am Hubland, suffered water damage to its holdings. A small number of books were dried by the freeze-dry technique. It appears that the library authorities were disappointed with the results; it was expected that after freeze-drying the books would be ready to put in the stacks. In another case involving water damage to materials of the archives of Beta Film GmbH, Munich, some unbound journals and other files were frozen to prevent microbiological attack. No vacuum freeze-drying was intended to follow. Instead, the materials were partly dried after a period of time in cold storage, then easily separated for conventional pressing and blotting (46).

10.1.6 Holland

Reported in 1985. The Central Research Laboratory for Objects of Art and Science had recent experience in freeze-drying water-damaged books from an archives building which had its roof blown away in a storm. Laboratory equipment was which, after some difficulties, produced relatively good results. In another project, equipment of the type found in the food industry has been tested. The Central Research Laboratory expects to have similar equipment of its own in the near future (47).

10.1.7 Norway

September 1985. Rare volumes stored in the cellar of the Kleist Library in Tronheim were damaged by water leakage. The books were stabilized by freezing. Meanwhile, the Archaeological Conservation Laboratory, Tronheim Museum, was asked for advice. Freeze-drying was recommended. Eventually, the frozen books were placed in a freeze-dry chamber of 40 kilograms (88 pounds) capacity. Each drying run lasted eight to 14 days depending on wetness; the project took 25 days to complete. Parchment covers were removed while wet and air-dried to prevent damage during freeze-drying. Some leathers were treated with a low concentration of polyethylene glycol 400 in water before freeze-drying for more flexibility after drying. At the end of the drying cycle, the paper of the books was slightly dehydrated. This was solved by placing the books in a room with 50 precept relative humidity. Some books were cockled but were smoothed out with light pressing. The freeze-dry chamber, housed at the Archaeological Laboratory, is used normally for treating artifacts of wood and leather (48).

10.1.8 USA

August 1975. On August 24th a cloudburst and subsequent floods inundated the library at Case-Western University in Cleveland, Ohio. Some 40,000 books, 50,000 maps and periodicals were soaked and damaged in the muddy water. Seven freezer trucks were loaded with 40,000 pounds (18,140 kilograms) of wet papers and sent to the vacuum chambers at McDonnell Douglas Aircraft Company at St. Louis, Missouri, for drying (39).

January 1977. On January 20th, Langley Hall at the University of Pittsburgh, Pennsylvania, suffered an explosion and fire from seepage of natural gas into the basement. The science and psychology library suffered extensive damage. The books wet from the fire hoses froze in place. Some 3,000 were stabilized in a freezer to await restoration (39).

February 1978. The San Diego Aerospace Museum and Library in California was destroyed by fire, apparently set by juvenile arsonists, on February 22nd. Ninety percent of the library's books, periodicals, films, photographs, and art were lost. Four large boxes of wet library materials rescued from the flames were frozen in cold storage. Here, the frozen materials were held until dried in a vacuum chamber. The materials were returned in good condition (39).

Reported in 1980. The Fall issue of the American Archivist reports that the University of Baltimore used a apace simulation chamber at Johns Hopkins Applied Physics Laboratory to save books and manuscripts damaged by water in the extinguishment of a fire. Several hundred books and documents were dried in the vacuum chamber (49).

Reported in 1980. The Winter issue of the American Archivist reports the use of space simulation chambers to dry out Kentucky State records damaged by flood waters of the Kentucky River in December 1978. Initially, microwave ovens were used to dry the damp records, but the process was abandoned as too slow. As a result, the General Electric Company, Valley Forge, Pennsylvania, and the McDonnell Douglas Aircraft Company, St. [outs, Missouri, were contracted for the project to dry, fumigate, and sterilize the water-damaged records (50).

The same issue of the American Archivist reports that the Idaho Historical Society has begun work on an emergency preservation plan which will outline actions to take in case of fire or flood. An essential part of the plan is to make prior arrangements for transporting water-damaged materials to local freezer and storage space. Local contacts will be made for commitments of temporary freezer storage space, transportation, carrying containers, and other supplies such as plastic sheeting and dehumidifiers. The emergency plan anticipates the use of freeze-drying for the recovery of most materials (51).

Reported in 1981. The News Bureau of the Lockheed Missiles and Space Company, Sunnyvale, California, reported in March of this year the successful freeze-drying, in a space simulation chamber, of more than 4,000 valuable books from the Doe Library Annex of the University at Berkeley. The books had been damaged by a defective sprinkler system that caused water to flow down and over the book stacks. The books were quickly sent to cold storage for stabilization while arrangements were made for drying.

In the same issue of News Bureau is another report on the use of freeze-drying: The drying of $3 million in counterfeit currency found in a slough. The United States Secret Service needed the currency to use as evidence in court proceedings (52)

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