Superhydrophobic coatings on wood made of plant oil and natural wax

Protection against wetting is a central issue in the finishing of wood, since water promotes degradation and reduced service life of the material. Ideally, wood finishes should provide efficient protection from water while at the same time preserving the overall bio-based character of the material. In order to meet this challenge, we propose a facile way to achieve superhydrophobic coatings on wood by using environmentally benign and even food-safe materials only. Spruce wood samples were dip-coated in a mixture of tung oil and natural beeswax, followed by the deposition of micronized sodium chloride particles. After a washing procedure, EDX confirmed that no sodium chloride remained at the surface. SEM-imaging illustrated the successful formation of a micro-structured topography endowing the surface with water repellence as indicated by stable static water contact angles above 160°. It is thus demonstrated that fully bio-based superhydrophobic wood coatings may be achieved using templating with water-soluble salt.