Chemical Processes in the Bleaching of Paper in Library and Archival Collections

The Chemistry of Paper Preservation: Part 2. The Yellowing of Paper and Conservation Bleaching

“…The structure of cellulose has been previously described in this Journal as a long, linear polymer based on repeating dimeric anhydrocellobiose units (1,18,19). During oxidation or photooxidation, carbonyl groups and carboxylic groups are formed from hydroxyl groups on the anhydroglucose units (16,17,20,21). The formation of both aldehyde and ketone groups on carbon atoms C-2 and C-3 in the anhydroglucose units accounts for the yellowing of cellulose during aging (16,17).…”

“…Paper is composed of cellulose, hemicellulose, lignin, and extraneous material from wood, plus dyes, additives, sizing agents, glue, starch, fillers, and pigments. As a consequence of oxidative reactions of these components, colored degradation products containing carbonyl (C=O) groups and carbon-carbon double bonds (C=C) can result (2,16,17). Oxidation is particularly affected by light, heat, moisture, the presence of metal cations such as Cu 2+ and Fe 3+ , and pollutant gases such as SO 2 and NO 2 (1).…”

“…The discoloration of paper is initiated by oxidation or photooxidation, a process whereby oxidation occurs following the absorption of light by the chromophores of the components of paper (16). Oxidative or photooxidative reactions can produce new functional groups that behave as new absorbing centers that account for the yellowing of paper (1).…”

Micro-XRF and FT-IR/ATR analyses of an optically degraded ancient document of the Trieste (Italy) cadastral system (1893): A novel and surprising iron gall ink protective action

“…4) [ [34][35][36]. The very brown edges of the same paper leaf are probably due to greater exposure to the surrounding environment, as compared with the internal areas of the sheet [37,38].…”

Colour stabilisation of wood composites using polyethylene glycol and melamine resin

“…The intensity data was calculated from absorption band areas relative to the intensity of the band at 895 cm -1 (wagging motion of the hydrogen on the C-1 position of the glucose ring in cellulose Ifju 1978, Feist andHon 1984), using the provided software. This reference is admissible because the C-1 position is stable in the oxidation process (Charter 1996, Durovič and Zellinger 1993, Hon 1981. Nevertheless, in composites or in polyethylene glycol-impregnated wood a superposition was observed at 895 cm -1 .…”