This research project was conducted to evaluate the effects of adhesive type, wood species, and cure temperature on the strength and durability properties of a finger joint. The adhesives were a resorcinol-formaldehyde (RF), polyurethane/aqueous emulsion polymer (PU/AEP), and a resorcinol formaldehyde/soy isolate honeymoon system. The species of wood were keruing (Dipterocarpus spp.), southern pine (Pinus spp.), and Douglas-fir (Pseudotsuga menziesii). The cure temperatures of the adhesives were ambient (26–35° C, 78–95° F) and elevated (43–49° C, 110–120° F). Joints were subjected to three test procedures; a tension test, a bending test, and a bending test following an accelerated aging procedure. The response variables measured for each of the bending tests included modulus of rupture, modulus of elasticity, and percent wood failure. The response variables measured for the tension tests were tensile strength and percent wood failure. The RF adhesive performed the best in flexural and tensile strength of the three adhesives studied. However in most cases, the PU/AEP adhesive could be considered a comparable system. Given adequate adhesive performance, strength and stiffness of the joints studied were dependent on density of the wood species, with keruing having the greatest density.
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