Adhesive performance of woods treated with alternative preservatives

The extended use of woods treated with traditional or alternative preservatives for exterior applications requires an assessment of wood adhesive performance. This study attempts to evaluate the performance of wood adhesives for woods treated with various waterborne preservatives. Two softwood species, i.e. Korean pine (Pinus koraiensis Sieb. et Zucc.) and Japanese Larch (Larix leptolepis [Sieb. et Zucc.] Gordon) were treated with copper–chrome–arsenic (CCA), CB-HDO, or copper azole (CY), and then bonded with four different wood adhesives such as urea–melamine–formaldehyde (UMF) resin, melamine–formaldehyde (MF) resin, phenol–formaldehyde (PF) resin, and resorcinol–formaldehyde (RF) resin. The performance of these adhesives was evaluated by measuring the dry shear strength of adhesive-bonded wood block on compression. Both UMF and MF resins produced a relatively strong adhesive strength for CY-treated pine and larch woods. The PF resin also produced good bond strength when bonded with either larch wood treated with CY or pinewood treated with CB-HDO. The best result was obtained when the CB-HDO-treated woods were bonded with RF resin. For a better bond strength development, a proper combination of adhesive, preservative, and wood species should be selected by taking into consideration of the characteristics of these three parameters as well as their interactions.