Phenolic glue extenders/fillers from mountain pine beetle (MPB)-attacked wood (sander dust, bark and wood particles) were developed as substitutes for corncob to reduce the costs of plywood manufacturing. Laboratory tests of the bonding performance of plywood panels produced with these new glue mixes generally exceeded the standard requirements for Canadian plywood in terms of wood failure percentage under both vacuum-pressure and boil-dry-boil conditions. All alternative extenders/fillers, except one: mountain pine beetle bark, increased the viscosity of glue mixes. The glue mix formulations may need to be adjusted in commercial production to minimize the impact on the glue application process.
Among these alternative glue extenders/fillers, sander dust is the most promising substitute for corncob since it is a by-product from the production of medium density fiberboard (MDF) production or particleboard, and as such has little value. With little treatment, it can be applied in a phenol-formaldehyde (PF) glue mix to partially or fully substitute for corncob. This will reduce cost and ensure a steady supply of extenders/fillers.
It is recommended that a mill trial be conducted to confirm and quantify the economic benefits.