The influence of log soaking temperature on surface quality and integrity performance of birch (Betula pendula Roth) veneer

Abstract

Wood material surface properties play an important role in adhesive bond formation and performance. In the present study, a test method was developed to evaluate the integrity of the wood surface, and the results were used to understand bond performance. Materials used were rotary cut birch (Betula pendula Roth) veneers, produced from logs soaked at 20 or 70 °C prior to peeling and followed by drying at 160 °C. Surface quality was evaluated through surface roughness measurement, SEM imaging, lathe check depth evaluation and surface integrity testing. The results show that soaking logs at 70 °C rather than at 20 °C before peeling produced veneers with decreased surface roughness, shallower lathe checks and better integrity. All these parameters are mainly affected by the lathe check depth, which is observed on the loose side of veneer. On the tight side of veneer, the only detectable differences were the mode of cell wall failure observed under SEM, and the greater amount of very fine particles loosely bound to the surface. Higher soaking temperature also produced a surface with 'hairy' structure and larger surface area, which could promote strong adhesive bond development. The surface integrity measurements were found to be very useful for evaluating the quality of veneer surfaces.

Citation

Rohumaa, Anti; Antikainen, Toni; Hunt, Christopher G.; Frihart, Charles R.; Hughes, Mark. 2016. The influence of log soaking temperature on surface quality and integrity performance of birch (Betula pendula Roth) veneer. Wood Science and Technology. 50(3): 463-474.