Boron Diffusion in Surface-Treated Framing Lumber

Abstract The extent of boron penetration in framing lumber treated by spray applications during construction is not well quantified. This study evaluated the effect of formulation and concentration on diffusion of boron in lumber specimens that were equilibrated in conditions that produced wood moisture contents of 18 to 21 percent. One set of specimens was pressure treated with water before equilibration. Borate solutions were prepared from powdered disodium octaborate tetrahydrate (DOT) or from two commercial glycol-borate formulations and applied with a garden-type sprayer. The DOT solution was applied at a 15 percent concentration, while the glycol-borate formulations were applied at 15 and 23 percent concentrations. Boron penetration was evaluated after 6, 13, and 26 weeks and boron retention after 26 weeks of diffusion. Boron penetration was observed for all treatments and progressed for the duration of the study. There was no significant penetration difference between the powdered DOT and glycol-bo...