The visualization of low-molecule phenol (LMP) and copper naphthenate on treated wood using X-ray microtomography

Recently, the plywood industry has been using low-molecule phenol (LMP) to enhance the dimensional stability of inferior-quality wood, along with copper naphthenate to increase veneer durability against staining fungi as a wood preservative. Non-destructive X-ray microtomography is a promising visualization method for reviewing the distribution of these materials. This study aimed to determine the applicability of X-ray microtomography for observing the distribution of LMP and Cu in two-and three-dimensional visualizations. The distribution mechanisms of these materials were investigated using X-ray images and image plot profiles. Six hardwood (wood from broad-leaved trees) and one softwood (wood from conifer trees) species were used for the experiments. An impregnation process was used to treat the wood samples with LMP, and copper naphthenate was added by dipping the wood in the compound for 1 s. A 10 mm² sample of each wood species was scanned using X-ray microtomography, and the distribution of LMP and Cu was successfully visualized using X-ray microtomography with the same settings. The LMP was displayed approximately evenly throughout the veneer, whereas the copper naphthenate existed mainly on the veneer surface. The X-ray images successfully showed penetration at the microscopic scale.