Deacidification permanence

In consideration of the damage of paper by liquids (solvents) as well as the limitation and effectiveness of transfer chemicals into the fibers, deacidification by gas has been devised. Although there are a great many volatile organic compounds which appear to be sufficient alkaline for vapor-phase deacidification, only a very few appear to be practical. Kathpalia (35), at the Nehru Library in New Delhi, exposed books to high concentrations of amnonia vapor for deacidification. However, it was found that amnonia is a too weak base to completely neutralize strong acid in paper, and amnonia volatilized from treated books in a few days. It has not been considered as a permanent deacidification method. 

The permanence of the deacidification has been tested by heating the deacidified paper samples to 150°C (300F) without increasing the acidity. The vapor from CHC has a very disagreeable odor, that would create an unpleasant atmosphere not only for those handling the material, but also in the stacks of books treated with CHC. CHC is reported to cause nausea and skin and eye irritation (46-54). More importantly, chronic and acute toxic effects have been observed in experimental animals exposed to varying concentration of CHC vapor, sometimes resulting in death (50,54). 

Permanence of Deacidification. If paper were composed of chemically inert fibers, one would expect that a brief exposure to the alkaline vapor of morpholine would have no appreciable effect since there would... 

Paper may be deacidified to make it more permanent. Since the paper often has become brittle before it is treated, methods are needed for increasing folding endurance that may be applied in conjunction with deacidification. In this study, the effects of sorbitol and Hercules Kymene 557H on the folding endurance of three papers alkalized with magnesium carbonate are explored. A synergistic action of the reagents is apparent. 

Cyclohexylamine carbonate, morpholine, amines in general and ammonia itself have all been considered as deacidifying treatments. Many are liquids with a significant vapour pressure or are gases, which makes them potentially useful for mass processes. However, all suffer from the problem that the deacidification produced is not permanent and some cause yellowing of the paper. None is currently in favour. 

The main cause for paper deterioration in libraries and archives is the acid catalyzed hydrolysis of cellulose, the ingredient that gives permanence to the paper. The aging permanence of paper is closely coimected with the add concentration in the paper. The priority in preservation measures is in most cases the dead-dification of acid paper. Today, more than 70 years after Barrow s pioneering work, mass deacidification of books and archive materials has become a commerdal reality. 

As acid catalyzed hydrolysis of cellulose is responsible for up to 90% of paper s loss of permanence, researchers have concentrated on deacidification as the primary solution to the impermanence of modern papers. Paper deacidification involves introduction of a strong base to convert acid spedes to their corresponding neutral salts, and the establishment of a neutral buffer to protect the paper against future acidcatalyzed damage. The first recorded attempt to neutralize paper was by Arthur Church at the Victoria and Albert Museum in London who, in 1891, advocated the immersion of paper in a methanolic solution of barium hydroxide [8]. 

Ethanolate and propanolate of magnesium which are dissolved in the appropriate alcohol and a nonpolar halogenated hydrocarbon can also be used as deacidification agents. By transformation of the magnesium alcoholate in the appropriate carbonates (aUcoxy magnesium carbonate) using (dry) carbon dioxide, a further improvement of the solubiHty and permanence could be reached. 

D. K. Sebera, The Effects of Strengthening and Deacidification on Paper Permanence Part I - Some Fundamental Considerations, Book and Paper Group Annual 1990, 66-111. 

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