Nanocellulose-based materials for the reinforcement of modern canvas-supported paintings

The aim of this work was to evaluate the use of novel nanocellulose-based consolidants for modern easel paintings as a possible alternative to lining and to the use of common adhesives. Two dispersions of consolidants were tested: nanofibrillated (CNF) and nanocrystalline cellulose (CNC). A model cotton canvas was used to evaluate the effect of these consolidants following treatment by the nanocellulose-based formulations. The surface appearance of the canvases was assessed before and after treatment using colorimetry and scanning electron microscopy (SEM). Additionally, the characterisation of the mechanical properties of the samples was performed using tensile testing and dynamic mechanical analysis (DMA-RH) at controlled relative humidity (RH) (3 RH cycles, 20-60-20% RH at 25 °C) before and after treatment. Finally, colour changes undergone by the samples upon accelerated ageing were measured by colorimetry. Taking into account the individual outcomes of each of these tests, it was possible to evaluate the merits and limitations of the use of nanocellulose treatments for the consolidation of modern painting canvases

On the potential of using nanocellulose for consolidation of painting canvases

Nanocellulose has been recently proposed as a novel consolidant for historical papers. Its use for painting canvas consolidation, however, remains unexplored. Here, we show for the first time how different nanocelluloses, namely mechanically isolated cellulose nanofibrils (CNF), carboxymethylated cellulose nanofibrils (CCNF) and cellulose nanocrystals (CNC), act as a bio-based alternative to synthetic resins and other conventional canvas consolidants. Importantly, we demonstrate that compared to some traditional consolidants, all tested nanocelluloses provided reinforcement in the adequate elongation regime. CCNF showed the best consolidation per added weight; however, it had to be handled at very low solids content compared to other nanocelluloses, exposing canvases to larger water volumes. CNC reinforced the least per added weight but could be used in more concentrated suspensions, giving the strongest consolidation after an equivalent number of coatings. CNF performed between CNC and CCNF. All nanocelluloses showed better consolidation than lining with synthetic adhesive (Beva 371) and linen canvas in the elongation region of interest