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Mass deacidification


Mass deacidification is a term used in Library and Information Science for one possible measure against the degradation of paper in old books (the so-called "slow fires"). The goal of the process is to increase the pH of acidic paper on a large scale. Although acid-free paper has become more common, a large body of acidic paper still exists in books made after the 1850s because of its cheaper and simpler production methods. Acidic paper, especially when exposed to light, air pollution, or high relative humidity, yellows and becomes brittle over time. During mass deacidification an alkaline agent is deposited in the paper to neutralize existing acid and prevent further decay.

There are several commercial deacidification techniques currently on the market.

BookKeeper, CSC Booksaver, Papersave and Wei T'o are also available as a hand held sprays.

These are the results that the Library of Congress expected of an ideal mass deacidification treatment in 1994.

Faculty members of the Slovak University of Technology added these further requirements.

All of the processes imparted an adequately high pH in studies conducted by the European Commission on Preservation and Access, the Library of Congress, and a team of scientists from the Centre de Recherches sur la Conservation des Documents Graphiques in the early and mid-nineties. BookKeeper produced a pH of 9-10. CSC Book Saver gives a pH of 8.78-10.5. Wei T'o gives 7.5 to 10.4, and Papersave gives a pH of 7.5-9.

The same studies also found that the processes had negative cosmetic side effects. BookKeeper left "a palpable residue", clamp marks on the covers, and caused some of the colored inks to rub off. CSC Book Saver left a "white powdery deposit" on books. Papersave caused "discoloration, white deposit, Newton rings, bleeding of inks and dyes, odor and different 'feel' of the paper." Wei T'o caused "odor, white residues, rings, cockling, (yellow) discolorations and adhesive bleeding."

Conservators from the British Library acknowledge that the existing mass deacidification processes are still developing and further research needs to be conducted on their chemical and mechanical effects.


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