Deacidification for the conservation and preservation of paper-based works: A review

Abstract

Embrittlement threatens the useful lifetime of books, maps, manuscripts, and works of art on paper during storage, circulation, and display in libraries, museums, and archives. Past studies have traced much of the embrittlement to the Brønsted-acidic conditions under which printing papers have been made, especially during the period between the mid-1800s to about 1990. This article reviews measures that conservators and collection managers have taken to reduce the acidity of books and other paper-based materials, thereby decreasing the rates of acidcatalyzed hydrolysis and other changes leading to embrittlement. Technical challenges include the selection of an alkaline additive, selecting and implementing a way to distribute this alkaline substance uniformly in the sheet and bound volumes, avoiding excessively high pH conditions, minimizing the rate of loss of physical properties such as resistance to folding, and avoiding any conditions that cause evident damage to the documents one is trying to preserve. Developers have achieved considerable progress, and modern librarians and researchers have many procedures from which to choose as a starting point for further developments.

Stability of Alum-Containing Paper under Alkaline Conditions

“…As mentioned above, paper can be stabilized against hydrolytic degradation using various deacidification agents and techniques [ 64 , 65 , 66 , 67 , 68 ]. An increase in pH leads, however, to a higher vulnerability to oxidative degradation.…”

Nonaqueous solution deacidification treatments to prolong the storage life of acidic books: A review of mechanistic and process aspects

“…A critical need for wide-scale implementation of deacidification treatment for acidic books already has been discussed in earlier articles (Williams 1971;Wilson and Parks 1979;Smith 1987;Baty et al 2010). Acidity within the pages of books, whether it comes from the acidic conditions under which the paper was produced, from acidic components of the lignocellulosic material, or from air pollution, will catalyze hydrolytic breakdown of the cellulose within the fibers (Smith 1969).…”

“…In addition to the criteria that can be regarded as essential to achieving deacidification, some authors have specified that an ideal mass deacidification treatment also ought to address other paper characteristics, such as strength, resistance to mold, and washing away contaminants (Daniels 1996;Andres 2006;Baty et al 2010). Among these characteristics, the improvement of paper strength seems to pose the most daunting challenges within the constraint of purely nonaqueous treatments.…”

“…Commercially-demonstrated, solution-based nonaqueous deacidification practices will be introduced here, starting with a historical overview, then considering chemical aspects (focusing on the alkaline reagent and the solvent), then the procedural steps. Broad descriptions of the technology are given in the following sources (Smith 1987;Morrow 1988;Hon 1989;Schwerdt 1989;Blüher and Vogelsanger 2001;Baty et al 2010;Ahn et al 2012a).…”

“…At the heart of some of the most successful and important systems for the massdeacidification of books and archival materialto increase their useful lifetimesis a class of treatments employing organometallic agents dissolved in nonpolar solvents (Hon 1989;Porck 1996;Blüher and Vogelsanger 2001;Cedzova et al 2006;Ramin et al 2009;Baty et al 2010). Such systems have demonstrated high performance in maintaining paper strength when the documents were subsequently subjected to accelerated aging (Brandis 1994;Andres et al 2008;Ramin et al 2009;Ahn et al 2012a;Katuscak et al 2012;Hubbe et al 2017).…”