Multi-analytical approaches for the characterisation and consolidation of ancient and modern manuscripts

Paper is generally considered to be a low-price mass product. However, as a substrate for historical or important documents and works of art, paper can be of great value. In this context, understanding the detailed chemical composition of paper can be important and useful for a variety of different purposes. It can provide information on historical paper-making practices and assist paper conservators in evaluating the state of preservation of old papers as well as in finding suitable measures for paper preservation or restoration. Furthermore, the chemical analysis of paper can help to reveal forgeries of works of art or other documents. The presence of certain chemical substances can provide information on the possible age of a sheet of paper. This information includes the main paper components such as fibres, filler pigments, sizing agents and others. Besides the components that are intentionally added to the paper, there are also other substances that occur as trace particles together with the main components in the paper or substances that were created during the paper production process. With this aim, a multi analytical approach is developed during this PhD thesis to study and characterise ancient and modern paper, to understand their conservation state; moreover, another goal is to help restaurateurs during the cleaning and consolidation procedures of paper artworks. Both spectroscopic and chromatographic analyses, in particular, have been carried out and new electrochemical monitoring tool will be proposed for monitoring the cleaning treatment of these papers. The multi-analytical approach to characterise the ancient paper has involved two case studies relating to Christian -Arabic manuscripts of XII century, collected at Biblioteca Apostolica Vaticana (BAV) (see cap.4), and two letters of San Francesco di Sales of XV century, collected at Villa Chigi in Ariccia (Rome). The aim is to evaluate a state of conservation and understand the composition of these paper artworks. Particular attention has been paid to the use of nondestructive in situ tests and minimally destructive laboratory analyses, optimising, for the last point, an easy sampling method based on latex sponges. By doing this, the possibility to analyse the surface composition of artworks, without moving them from a museum or library to a laboratory or sacrifice a piece, is demonstrated. Moreover, modern papers have been analysed to understand the difference in composition with ancient artefacts; indeed the procedure for cleaning has been optimised. To consolidate the fragile paper artworks, cellulose nano-crystals preparations have been proposed as fillers for paper preservation for their compatibility with paper, their capacity to form a transparent film and their easiness to prepare and to apply without compromising the properties or the architecture of the paper. To validate this approach, a complete characterisation of paper treated with cellulose nanocrystal film has been carried out using pH, colorimetric, spectroscopic and tensile measurements; in particular the beneficial effects of cellulose nano-crystals for paper reinforcement have been demonstrated by the improvement of the mechanical properties through textile tests of specimens prepared in laboratory using two different preparations. The use of cellulose nanocrystal, as consolidant for degraded paper, is also investigated and applied on a real paper sample of 18th century. Moreover, the reversibility of the consolidation treatment, a pivotal requisite in Cultural Heritage restoration, here demonstrated for the first time by hydrogel application coupled to an electrochemical monitoring tool.