The effect of surface aging prior to gluing on the wettability and gluability of wood have been investigated. For experimental materials, the heartwood of Akamatsu (pinus densiflora SIEB. et ZUCC.), Kuromatsu (Pinus thunbergii PARL.) and Ezomatsu (Picea jezoensis CARR.) were used. Immediately after machining, the surface of lamina was exposed to the atomosphere but protected from the settling of airborne contaminate and exposure to light.
After a certain aging period, the wettability and gluability were determined. Urea- and resolsinol-formaldehyde resin adhesives, polyvinyl acetate emulsion and casein glue were used for gluing. Some of the glued wood were treated with heat at 100℃ for 24 hours maintaining the moisture of the wood at a constant level. The block shear strength test in air dried condition was carried out on the treated and untreated specimens.
The results obtained are as follows :
1) The wettability and gluability decreased with the increase of aging period, but Ezomatsu showed only a slight decrease.
2) Also, the glue-joint strength and wood failure of the treated specimens decreased with the increase of aging period. Particulaly, a remarkable degradation was observed on urea-formaldehyde resin adhesive.
3) In the specimens stored for six months, much delamination was observed.
4) Best gluabilty could be obtained when the surface was planed freshly at the time of gluing.