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| CSIRO | SOLVE | Issue 8 | Aug 06 | |
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ARTICLE
 WOOD: Hardwood Primed to Stick By Rebecca Thyer
Australia is well endowed with commercially important hardwoods, such as spotted gum, blackbutt and messmate. Yet their use in furniture and building materials is limited, particularly in outdoor applications, because they are notoriously difficult to bond and paint. The answer could be a simple, new water-based primer. The primer, a single-step treatment process, should help boost native hardwood use in timber furniture and building materials.
Professor Tom Spurling, CEO of the CRC Wood Innovations, says the industry had been looking to improve hardwood’s adhesion for some time. “Generally speaking softwoods are better at forming bonds than hardwoods,” he says. “If you compare the tensile strengths of bonded timbers, softwoods like radiata pine are at least twice as easy to bond as some of the Australian hardwoods.” Poor adhesion strength and large variability in the adhesive strength of bonded timber, and the need to bond or paint machined components as soon as possible after machining or sanding, have meant manufacturers often favour softwoods over comparatively troublesome hardwoods. CMMT’s new single-step process addresses these issues, substantially improving adhesion strength, overcoming hardwood’s variable and unpredictable surface chemistry and creating high strength and durability for hardwood products bonded or painted within a large timeframe after surface machining. Essentially a simple spray-on or brush-on application, the primer uses compact equipment compatible with existing manufacturing facilities, or DIY or in-field surface priming. Professor Spurling says the breakthrough was made possible because of CMMT’s long-term investment in the surface science of important industrial materials. “The timber industry has benefited from CSIRO’s long-term investment in surface and interphase science, which has allowed it to solve a key problem – poor adhesion.” CMMT project leader Dr Voytek Gutowski’s key research area is adhesion and functional surfaces. His team has had commercial success in developing improved adhesion solutions for plastic components used by GM Holden and other manufacturers. Dr Gutowski says hardwoods are natural polymers and their adhesion problems may be solved using approaches similar to those used in enhancing the adhesion of synthetic polymers. “Until now we were not dealing with timber at all, but we felt that we’d be reasonably comfortable looking into timber adhesion problems,” he says. “We’ve proved we can significantly improve the bonding of different hardwoods. It should lead to an increase in hardwood use by timber product manufacturers.”
He says the initial product range of primers could be broadened and used whenever improved adhesion and durability of adhesives, coatings and other materials is needed. “For example, the principle could be used in furniture, cladding materials or laminated products comprising wood veneer with other types of wood, metal or polymers.” For further information contact: |
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Developed by materials science researchers at CSIRO Manufacturing and Materials Technology (CMMT) and the Cooperative Research Centre (CRC) Wood Innovations, the primer improves the adhesive strength of hardwood timber by up to 400 per cent.
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