Samples of 100 x 50 mm² radiata pine were processed with a variety of options to produce dry, boron-treated wood. Concentrations of boric acid in the central one-ninth and in the whole of the wood cross-sections were determined by chemical analysis and compared. Diffusion treated material was dried by air, conventional kiln (70/60°C), or high temperature kiln (120/70°C). Four different predrying, pressure treatment, and redrying combinations were also evaluated, using a low net absorption (nominally 200 l/m³) treating process. Drying after diffusion treatment resulted in substantial redistribution of preservative towards the surface of the wood samples. In addition, a net loss of preservative from kiln-dried, diffusion-treated wood was observed. Pressure treated wood was much less affected. Mechanisms which may account for observations about the various processing options are postulated. Results are compared with those produced by Vapour Boron Process treatment of the same material. The advantages of this process are discussed, particularly in view of the recent extension of the New Zealand specifications for preservative treatment to include retention requirements for dry, boron-treated wood.

Download document (762 kb)
free for the members of IRG. Available if purchased.

Purchase this document