Wood preservation facilities, chromated copper arsenate: chapter B-2

2. Physical and Chemical Properties

The components of CCA (copper, chromium and arsenic) were selected for wood preservation use because of their biocidal properties and their ability to be retained within the wood for long-term protection. Fixation is a physical or chemical process whereby CCA is rendered leach-resistant in both water and soil applications in such a way that the active ingredient or ingredients maintain fungal/insecticidal efficacy (4). The fixation mechanism of CCA within wood is complex, and the reactions involved depend on the preservative formulation and concentration, wood species, temperature and humidity conditions (5). Reaction products include insoluble chromates and insoluble arsenates of copper and chromium (6).

General physical and chemical properties of CCA solution are summarized in Table 2. The data indicate that a wide variety of properties must be considered in order to safely manage CCA solutions. Detailed information can be obtained from manufacturers’ material safety data sheets (MSDS) and the pesticide label. Electronic copies of the pesticide labels can be obtained at the Health Canada website (7).