HOW ARE PRESERVATIVE CHEMICALS APPLIED TO WOOD?
Wood products for construction are typically treated in a factory, using a pressure process. The product is loaded into a vessel, then the vessel is filled with a water solution containing the preservative chemicals. The vessel is pressurised to force the solution into the wood. Most dimension lumber can be treated this way, as well as plywood and Parallam. Other composite products are hard to pressure-treat, for example, OSB, LVL and glulam. OSB, however, can be preservative-treated during production. Preservative chemicals are added to the mix of wood flakes and resin prior to pressing into boards. Preservatives can also be applied in the field, when a piece of treated lumber is cut. A cut end of treated lumber must be brushed with or dipped into a chemical, as this cut exposes untreated wood. The chemicals in treated wood, even though they have been applied under pressure, dont penetrate the wood all the way to the core.
