Fe-Sem Characterisation Of Pinus Radiata Solid Wood And Plywood Surfaces Following Machining

Abstract

Selection of coatings for good performance on textured wooden surfaces requires a sound knowledge of the wooden surface textures which result from machining treatments. In this work, Pinus radiata solid wood surfaces were planed, sanded and band-sawn while Pinus radiata plywood surfaces were peeled and rough-sawn. The impact of the various machining treatments was examined by field emission scanning electron microscopy. Particular emphasis was placed on micro-morphological characteristics of surface and sub-surface tissue layers. Planing and sanding resulted in even surface topographies. On planed surfaces, cell deformation and cell wall damage was confined to the outermost cell layers while on sanded surfaces they extended to one or two subsurface layers. Band-sawn solid wood surfaces and rough-sawn plywood surfaces were highly irregular, the result of distortion and loss of tissue masses along the outer face caused by forces generated during sawing. Cell wall level damage, such as delamination and cracking, were present in many cell layers below the surface. Compared to the band-sawn solid wood samples, tissue damage in rough-sawn plywood was more severe. These features are discussed in relation to how micromorphological damage embedded in the surface and subsurface tissue layers can create regions of a highly porous nature with increased surface area which are suited to coating entanglement.