Evaluation of color alterations due to Ag-functionalized nanocrystalline cellulose on Whatman and Amalfi paper

Great part of the History of mankind is registered in form of work of art on paper support. Paper can be deteriorated due to physical, chemical, and biological agents. Among these latter, fungi represent the major paper biodeteriogens. Several methods have been used to control or stop fungal deterioration on paper-based materials, but their use can in turn induce color variations on paper. In this work a treatment for preservation and consolidation, based on nanocrystalline cellulose and silver nanoparticles (CNC/Ag) is analyzed. Two different types of paper (Whatman #1 and Amalfi) are treated by means of the suspension. Then spectral reflectance measurements are performed to infer CIELAB color coordinates of treated and not treated paper, in order to study the differences. It has been found that the use of CNC/Ag induces a pink coloration in the paper (reducing its hue), determines a darkening effect (reducing its lightness) and increases the saturation. Moreover, these alterations get more significant on time varying.