Cellulose damage in historical papers

Paper deterioration threatens a large number of historical documents, prints, drawings and music scores of immense value. The conservator engaged with recovering and saving the precious objects needs to assess the extent of paper damage prior to any conservational treatment, which also means determination of the degradation state of cellulose as the main paper constituent. However, available methods to define cellulose damage are very limited. The present project proposal is concerned with the development of accurate chemical-analytical methodology to assess the state of cellulose damage in paper materials, which will be generally applicable in addition. The approach will be based on selective UV or fluorescence labeling of oxidized chemical functionalities in cellulose, which are a direct measure of hydrolytic and oxidative stress imposed. The labeled material is either studied by gel permeation chromatography (GPC) with multiple detection modes, which provides an in-depth analysis of the oxidized groups in relation to the celluloses molecular weight, so-called carbonyl and carboxyl "profiles", or it is examined by UV and confocal microscopy techniques. All approaches require only tolerably small sample amounts - in the low milligram range. By combining group-selective labeling with special microscopy techniques imaging of spatial and temporal progression of cellulose damage extending from heavily damage-inflicted areas, such as gall-ink lines, will become possible for the first time. As a quite large cellulose and paper matrix is available for sampling, damage categories will be established. Sample candidates from each category will be subjected to standard conservational treatments to clarify, which treatments are appropriate for each damage category, and which are not. As eventual project aim, a test kit will be developed which allows a facile, non-destructive evaluation of the oxidation state of cellulose and the respective damage category, mainly intended for quick and facile on-site use by conservationists. The methodology elaborated within this project is supposed to enter restoration and conservation science as chemical standard tests, but general applicability in the pulp and paper industry is also possible.