Analysis of degraded papers by non‐destructive spectroscopic techniques

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 β‐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.