19 ноября, 2015 
Pokraskin It is well known that the adhesion of an adhesive at the interfaces of the substrates depends on physico-chemical interactions and mechanical interlocking [23]. Apriori, in the case of porous surfaces, there is a larger area per joint section, and cavities enable the ‘tentacles’ of the adhesive to penetrate into the substrate. Machining techniques such as sawing, planing, filing, grinding, brushing or slicing all involve the processing of wood. The so-called ‘front face’ or ‘front end’ generally has larger pores as the cell cavities and interspaces are aligned along the direction of the fibers. Although as-sawn surfaces are less even than planed or ground surfaces, in the latter case ‘fragmental layers’ made from cell material may be detrimental to the quality of the bond, whereas during planing or slicing the cell walls are cut neatly and cleanly. Another important factor with regards to the behavior of the adhesive at the interphase is the density of the wood, and this depends on the species. Within any one species the density of early wood will differ from that of the late wood, as illustrated in Figure 8.19.
8.4.5
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