Analysis of degraded papers by non‐destructive spectroscopic techniques

Abstract

Scientific approach to cultural heritage conservation is very important for cultural reasons and also in order to avoid mistakes in restoration work. Acidity and oxidation play a very important role in paper conservation. Deacidification is a widely used method to remove acidity on aged papers, but if a large amount of carbonyl groups is present in the paper, a strong deacidification can promote an alkali-catalysed b-alkoxy elimination, leading to the breaking of the anhydroglucose ring in the cellulose chain.In this case, and also in the case of non-acidic but oxidised papers, a reduction treatment is necessary. Because of the high costs of restoration procedures, it is essential to determine whether the reduction treatment is a primary need.In this work we report a study, based on micron-scale space resolved Raman microscopy, infrared reflectance spectroscopy and atomic force microscopy, of differently degraded samples of paper.Non-treated and oxidised samples were investigated, as well as original ancient documents. The aim of this work is to achieve a better understanding of the degradation pattern of historical samples in order to be able to choose the most appropriate restoration treatment using non-destructive spectroscopic techniques.Analysis of the samples demonstrates that degradation processes occur mainly on fibrils and on the fibre wall, as shown also by atomic force microscopy measurements.

Degradation by-products of ancient paper leaves from wash waters

“…This signal is normally assigned to C=C symmetric stretching and O=C-O asymmetric stretching. 30,31 The presence of the carboxylate groups, identified in the FTIR and Raman spectra, is in agreement with the relatively high pH value of the Extract 1 (Table 1): it indicates that the carboxylic groups are mainly present in their deprotonated form, accounting for the high solubility of the Extract 1 only in a polar solvent like water. 45 Carboxylate species arise from low molecular mass organic acids, whose study in ancient and historical papers has been widespread in literature, and/or from oxidized glycosidic units of cellulose chain or, as in this case, oligomers (see below).…”

“…31 Fluorescence was quenched using the SERS technique to obtain the Raman spectrum. SERS signals were recorded in presence of naked Please do not adjust margins Please do not adjust margins gold nanoparticles of about 20 nm obtained by laser ablation synthesis in solution (LASiS).…”

Characterization of Pigment and Binder in Badly Conserved Illuminations of a 15th‐Century Manuscript

“…Using Raman spectroscopy, they identified the green pigment as verdigris, thus establishing that all three volumes showed evidence of some paper deterioration where verdigris was applied. We stress that, in our case, Raman spectroscopy was applied unsuccessfully on fragment A: a relevant fluorescence prevented the acquisition of a good Raman spectrum, which is not unusual for deteriorated paper (Bicchieri et al 2006). A muchquestioned copper pigment that we have not taken into account so far is copper resinate: according to De Mayerne's (1620) recipe, copper resinate is produced by dissolving verdigris in hot Venice turpentine and turpentine oil.…”

Recent Advances in linear and nonlinear Raman spectroscopy I

“…116 A fundamental problem in paper conservation and restoration is the identification and understanding of the cellulose degradation mechanisms which can be solved by Raman spectroscopy. 117 Raman spectroscopy can also be employed for the study of weathering alterations of sculptures. 118…”