How does the pressure treating process work?
This is the simplified version of the process: Most pieces of wood (South Yellow Pine among the exceptions) are incised, prior to being pressure treated. The incising procedure is what puts the familiar “divots” in the lumber surface. Incising allows the treating chemicals to more thoroughly penetrate the lumber. After incising, the lumber is loaded onto what looks like a railroad flat car. This flat car is pushed into a long tube called a retort. Once in the retort, preservative chemicals in a water solution are forced into the lumber. This is done under pressure until saturation is reached. After removal from the retort, the treated lumber is allowed to drip dry. It is then tested to make sure preservative chemicals have penetrated adequately in depth and quantity.
