An investigation of the effects on decay and termite resistance of a wood modification process involving prepolymers of hexamethoxymethyl melamine (HMMM) was conducted using LVL as a model engineered wood product. Dry Pinus radiata veneers were vacuum-impregnated with a wood modification formulation containing a mixture (P-H:S-H) of two separate prepolymerisation reactions containing polyvinyl alcohol and HMMM, and sucrose and HMMM. Veneers were re-dried at 30C, assembled as 12-ply lay up and hot pressed at 160C for 30 min. Test specimens subjected to laboratory decay tests performed according to AWPC showed either no change or small decreases in susceptibility to three brown rot fungi Coniophora puteana, Fomitopsis lilacino-gilva and Tyromyces palustris when compared to unmodified controls. The inhibitory effects were generally more apparent in leached veneers. Modified LVL specimens exposed to Coptotermes acinaciformis termites showed only a small degree of protection and no change in surface grazing of superficial veneers. Therefore, although P-H:S-H modification of engineered wood products produces significant performance benefits with respect to physical properties, it can not be used in the field without the addition of wood preservatives. The biological effects of P-H:S-H modification are compared with a number of other wood modification processes.

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