Shellac​/nanoparticles dispersions as protective materials for wood

Wood is a natural material that finds numerous and widespread applications, but is subject to different decay processes. Surface coating is the most common method used to protect wood against deterioration and to improve and stabilize its distinctive appearance. Shellac is a natural resin that has been widely used as a protective material for wooden artifacts (e.g. furniture, musical instruments)​, due to its excellent properties. Nevertheless, diffusion of shellac-​based varnishes has significantly declined during the last decades, because of some limitations such as the softness of the coating, photo-​degrdn., and sensitivity to alc. solvents and to pH variations. In the present study, different inorg. nanoparticles were dispersed into dewaxed natural shellac and the resulting materials were investigated even after application on wood specimens in order to assess variations of the coating properties. Analyses performed by a variety of exptl. techniques have shown that dispersed nanoparticles do not significantly affect some distinctive and desirable features of the shellac varnish such as chromatic aspect, film-​forming ability, water repellence, and adhesion. On the other hand, the obtained results suggested that some weak points of the coating, such as low hardness and poor resistance to UV-​induced ageing, can be improved by adding ZrO2 and ZnO nanoparticles, resp.