Surface finishes by mechanically induced wood surface fusion

Mechanically induced vibration wood fusion welding techniques can also be used to obtain wood surface finishes of increased surface hardness and performance in presence of polymerizing unsaturated oils such as sunflower oil, or other polymerizing finishes. Wood surface hardness values more than double than those for the untreated control timber can be obtained by this method. This result is obtained due to two effects induced by the sharp increase in temperature induced by the mechanical welding vibration (i) the polymerization to a hardened network of the unsaturated oil and (ii) the densification proven to occur in the surface layer of the timber during mechanically-induced vibration-welding. The first of these effects predominates at shorter welding times while at slightly longer welding times both effects occur with the second one progressively becoming the bigger contributor. In the latter case the some μm thin densified surface is a surface composite formed by the networked unsaturated oil permeating the wood fibre/fused lignin composite. © Springer-Verlag 2005.