Combined Nanocellulose/Nanosilica Approach for Multiscale Consolidation of Painting Canvases

The restoration of painting canvases is a complex problem that, because of the hierarchical nature of the canvas, requires intervention at several length scales. We propose an approach combining polyelectrolyte-treated silica nanoparticles (SNP) and cellulose nanofibrils (CNF) for canvas consolidation. The formulations, applied on model degraded canvases, gave a total weight increase of <5 wt %. Scanning electron microscopy and micro-X-ray fluorescence measurements were used for determining the component distribution across the canvas depth, while tensile testing demonstrated the mechanical efficiency of the consolidation. CNF formed a film at the canvas surface that increased the ductility. SNP penetrated deeper and reinforced at the fiber scale, yielding higher stiffness. The two effects could be balanced by varying the SNP/CNF ratio a suitable reinforcement. This approach offers an alternative to the conventional treatments based on e.g., relining with a new canvas or application of synthetic film-forming compounds.