Nonaqueous deacidification

Considerable research is being devoted to improve existing techniques, to accelerate the deacidification process, render it applicable for the treatment of bound volumes and reduce the cost of operations. Nonaqueous deacidification has been improved in the past ten years and has reached commercial success. The new process is conducted by introducing "liquified gas" into a chamber containing books. Once the acid ions in the paper have been neutralized, the "gas" is pumped out of the compression chamber and returned to a storage tank. The books can then be dried and return to the shelves. Since a nonaqueous deacidification process does not require books to be unbound as does an aqueous process, its development dramatically reduced the cost of operation. 

The most successful nonaqueous deacidification treatment is the Wei T o process which uses solutions of methoxy magnesium methyl carbonate in alcohol and Freon as the starting materials (33). The spray deacidification of the solution on books is now in use at the... 

R. D. Smith, The History and use of magnesium alkoxides in the nonaqueous deacidification of books, documents and works of art on paper. Paper presented at the 1983 Annual Meeting of Internationale Arbeitsgemeinschaft der Archiv-, Bibliothek- und Graphikrestauratoren (LADA), The Hague, Netherlands,... 

Methylmagnesium Carbonate—An Improved Nonaqueous Deacidification Agent... 

The detrimental effect of acid in paper has been well documented (1, 2, 3, 4), and numerous treatments have been proposed to alleviate the effect. Schierholz (5), Barrow (6), and others have proposed methods of neutralizing the acids in paper based on aqueous treatments. However, many papers are sensitive to aqueous treatments, either because of the fragility of the paper or the tendency of the inks or colors to run when exposed to water, and for these papers a nonaqueous deacidification treatment is required. 

One of the most widely used nonaqueous deacidification processes is that proposed by Smith (7) based on a methanol or methanol-Freon solution of magnesium methoxide. This process is very effective and leaves a good alkaline reserve, but the magnesium methoxide is very sensitive to water, and this leads to inconvenience in the handling and processing of paper as a result of premature precipitation. These inconveniences were recognized, and a better nonaqueous deacidification agent... 

Temptation to do-it-yourself, however, is always present library materials needing repair grow more numerous every day, and at the same time the market offers increasing numbers of tempting proprietary products that are advertised as being of archival quality—as indeed some are. The list includes dry mounting film and tissues, heatset tissues, pressure-sensitive tapes, rag boards (which may be made from cotton and/or wood fiber), storage containers, and nonaqueous deacidification solutions. 

Nonaqueous deacidification systems contain a deacidification agent and an organic solvent that serves as the carrier. The solvents offer the advantage of rapid penetration and drying. The latter is particularly important in minimizing the... 

Four mass deacidification processes for book preservation namely, the Library of Congress diethyl zine process, Wei T o nonaqueous process, Kopper s "Book Keeper" process, and Langwell interleaf vapor phase process, are critically evaluated, based on their chemical characteristics and effectiveness on deacidification. 

Much of this material should be deacidified, but only the experienced can decide whether aqueous or nonaqueous methods should be used, and only they are likely to have the manual dexterity and knowledge of handling techniques which in many instances are essential if damage is to be avoided. The method of deacidification depends on the nature of the paper and inks and pigments. Sometimes the paper cannot be treated at all because the colors of the image would be changed. 

Chemistry, Physics, and Biology Laboratories. As a rule, before any artifact is subjected to treatment, the chemistry laboratory determines the causes of any alterations or deterioration. The nature and structure of the artifact, its pigments and inks, are identified to avoid negative reactions to prescribed treatment. Fixatives are recommended if required these may be cellulose acetate dissolved in acetone, soluble nylon, or acrylic resin sprays. Once stains are identified, several possible solvents are selected. For deacidification, either magnesium bicarbonate or barium hydroxide usually is recommended, depending on whether an aqueous or nonaqueous solution is called for. Bleaching is discouraged, but when necessary, hypochlorites are used with suitable antichlors. 

Wei T o Associates, developers of a nonaqueous liquid deacidification process, derives its name from an ancient Qiinese god regarded as the protector of books. The National Archives of Canada operated a treatment facility in Ottawa with a capacity of about 40000 books per year until 2002. The process is based on the work conducted by Richard D. Smith, a graduate student at the University of Chicago in the mid-1960s. In 1989, Union Carbide acquired the exclusive rights of the process and intend to market the technique as part of a paper preservation service unit... 

There are some successful new possibilities in the deaddification of paper up to mass deacidification processes by nonpolar solvents (for example the Papersave Process ) whereas no new achievements have been reached in the strengthening of paper, especially not in nonaqueous treatments. The experiences of paper makers are only of limited use in the strengthening of old papers because the papers cannot be changed in structure and compound during restoration or preservation. 

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