The mechanism of failure of clear coated wooden boards as revealed by microscopy

Abstract

Regions of wood-coating interface from clear coated Pinus radiata boards were examined by a combination of light and transmission electron microscopy techniques after six months exposure outdoors in order to understand the mechanism of clear coating failure. The primary cause of coating failure was the separation of cells in the surface layers of wood underlying the coating that was caused mainly by the photodegradation of the middle lamella. These results are discussed in the light of known effects of solar radiation on lignin and other components of wood cell walls.