Preliminary Evaluation of Copper Leaching from Commercially Available Wood Species in Japan Treated with Copper Azole Wood Preservative
This study examined copper fixation and leaching in wood treated with copper azole (CuAz) and copper sulfate (CuSO₄), emphasizing the effects of wood species and post-treatment conditions. Five Japanese softwoods, including Sugi, Hinoki, and Douglas fir, were assessed under three conditions: unfixed, ambient-fixed, and heat-treated (60°C for 3 days). Copper fixation was defined as the proportion of non-leachable copper remaining after standardized leaching, with release rates measured via leachate analysis. Results showed that post-treatment condition is the dominant factor controlling copper stabilization. Heat treatment significantly enhanced fixation and reduced leaching across all species and preservative types, indicating improved bonding between copper ions and wood components. Ambient fixation was often insufficient. Sugi sapwood showed the highest leaching, while Hinoki heartwood exhibited the greatest retention. Overall, CuAz outperformed CuSO₄, underscoring the importance of formulation in improving copper stability and durability.
