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.

The kinetics of the spontaneous, proton- and AlIII-catalysed hydrolyses of the C1—O4′ bond in 1,5-anhydrocellobiitol have been measured at elevated temperatures (125.0–220.0 °C). Data for the first two processes extrapolate to the expression k = (8.6 ± 2.1 × 10–16) + (1.4 ± 0.2 × 10–9-pH) s–1 at 25 °C. These room-temperature figures were used to model cellulose depolymerization by the af Ekenstam equation. The spontaneous process is too slow to contribute to loss of paper strength on aging, and even the acid-catalysed process is significant only below ~pH 4.0. However, the spontaneous hydrolysis readily accounts for the reduction of cellulose degree of polymerization (DP) during alkaline (e.g., kraft) pulping of cellulose fibres. Efficient electrophilic catalysis by AlIII was observed at 150.0 °C in 0.1 mol/L succinate buffers of room temperature pH 3.05 and 3.35 (k2 = 8.1 ± 0.4 × 10–3 and 4.2 ± 0.2 × 10–3 (mol/L) –1 s–1, respectively). The apparent activation energy of the AlIII-catalysed process was 31 ± 4 kJ mol-1, lower than that of the proton-catalysed path, suggesting the electrophilic catalysis increases in importance as the temperature approaches ambient. Consequently, it appears that the culprit in the impermanence of “rosin-alum” -sized paper is AlIII, directly acting as a Lewis acid, not the AlIII hydration sphere as a Brønsted acid. Conservation measures should either address this or be generic (e.g., low-temperature storage). Key words: cellulose, hydrolysis, kraft pulping, paper conservation, rosin-alum sizing.

Added Al2SO4 greatly accelerates the hydrolysis at 150.0 degrees C of 1,5-anhydrocellobiitol, a model for the beta(1 --> 4) linkages in cellulose, in succinate buffers of room temperature pH 3.05 and 3.35; E(a) values for 20 mM Al(III)- and H+-catalysed hydrolyses are 109 +/- 3 and 140 +/- 1 kJ mol(-1), respectively.

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AbstractCellulose acetate (CA) lamination, a technique to strengthen documents by sealing them between sheets of thermoplastic film, was widespread from the 1930s to the 1990s. Its use gradually stopped in the 1980s amid concerns about the physical and chemical instability of the laminate and the degradation risks posed to the treated document. Despite concerns about CA lamination, no coordinated effort has taken place to establish the various materials and techniques used in cellulose acetate laminations or to determine the number and present condition of CA laminated documents in US collections. In this paper, we review the chemistry and methods used in CA lamination. We then report results of a survey of 52 US institutions with significant laminated collections. We find that at least 2.9 million laminated documents exist in US collections, and most of those documents are observed to be in stable condition. A majority of the institutions used cellulose diacetate (CDA) as the laminating film and as few as 0.6% CDA laminated documents have been delaminated. The results should aid institutions in determining the cost benefit in the management of these significant collections.