Many of the chemicals used in wood preservative formulations interact both physically and chemically with the wood substrate. The inorganic salts, principally copper and chromium, undergo complex reactions to form organometallic and inorganic complexes that render them non-leachable. Organic compounds undergo a simple physical interaction with wood, which may be either confined to the gross structure or may involve microdistribution within the cell wall. The type of distribution can significantly affect the performance of preservatives. -- AATA