Over the past 100 years, the Forest Products Laboratory (FPL) has gained notoriety for pioneering techniques such as Best Opening Face (which optimized 1970’s softwood dimension sawmills and, in part, prevented an industry collapse), and more recently, cellulose nanofibril technology (which is revolutionizing the way we use low-value forest material). Despite these headline-making developments, there still exist several unsung heroes of timber processing — and although these may be less glamorous cousins to the cutting-edge biodegradable computer chips of the nanocellulose lab, they remain indispensable nonetheless.
One of these products is veneer.
Veneer is wood that has been cut from a log using a sharp knife rather than a saw. Veneer can be “peeled” or “sliced.” When peeling, like a paper towel off a roll, the log (bolt) is turned against a knife and a thin layer of wood is cut (peeled). When slicing, the log is affixed and the knife moves up and down, slicing parallel to the length of the log.
The veneer is then clipped (or sawed) to a specified length, dried, and stacked.
Although these thin sheets of wood can be used superficially to improve the appearance of counter tops and floors, veneer is also the basic component of laminated veneer lumber or plywood.
The wood properties of these laminated sheets are essentially the same as sawn wood, but the surface of the wood — as a result of cutting, drying, and laminating into plywood — can significantly change the characteristics of the veneer. FPL helped refine all phases of veneer production, so that the final products had improved surface, durability, and strength.
FPL researchers further improved on existing methods to efficiently peel the wood so that more of the log could be converted into veneer, including development of specialized pre-heating “cooking“ schedules for softening the wood prior to veneer peeling. FPL research on processing variables resulted in reduction of thickness variations caused from uneven peeler crushing because of the large difference in density between earlywood and latewood. This significantly improved the processing of Douglas-fir and southern pine, and helped turn small-diameter trees into useful structural materials.
Finally, to help transfer FPL research to industry, the Laboratory set up a Veneer Mill Improvement Program (VIP). This program measured veneer mill raw-material conversion efficiency and, with aid of a computer simulation model, could predict gains from process improvements. The VIP analyzed log bucking, block centering in the lathe, and veneer peeling and clipping. This information was used to identify areas where improvements were feasible and helped turn veneer production into a viable industry in the 1960’s.
Today, plywood remains a staple of building construction, and it stands to be a mainstay for years to come. In addition to its role in traditional walls, some new types of Structural Insulated Panels (SIPs) use plywood around an thermally-efficient foam core. This sandwiched product will help us meet the stringent energy codes of tomorrow, and carry on the tradition of veneer, plywood, and research here at FPL.
For more information, please see Forest Products Laboratory, 1910–2010 Celebrating a Century of Accomplishments.