Water Permeability and Adhesion Strength of Bio-based Coating Applied on Wood

The main task of wood manufacturers is to ensure the supply of safe wood products. In this respect, the use of plants as raw material for the wood coatings production is a sustainable alternative to fossil fuels, especially since innovative materials minimize the health and environmental risks of the final product over its entire lifespan. This paper presents a study of the water permeability of a water-borne bio-based coating applied to spruce (Picea abies), a study of the adhesion strength of the same coating applied to spruce (Picea abies), beech (Fagus sylvatica L.) and beech plywood, as well as a study of the adhesion strength on spruce after the water permeability test. The tests were performed according to EN 927-5:2006 and EN ISO 4624:2016. The roughness parameters were measured before and after the water permeability test. The coating was found to be hydrophobic but also water permeable. The highest value of adhesion strength was observed for beech surface, the lowest for spruce. The changes in the surface profiles after the water permeability test are insignificant. According to the water absorption criteria, this coating system could only be applied on exterior wood intended for end-use categores such as overlapping cladding, fencing, garden sheds, open cladding, and ventilated rain screen.