Preservative treatment of red maple

The development of additional preservative treatments for underutilized eastern hardwoods, such as red maple, is critical to the development of new market opportunities that require long-term utilization of hardwoods in exterior structures. This project investigated the treatability of red maple sapwood and heartwood with water, toluene, CCA (chromated copper arsenate), ACQ (ammonium copper didecyldimethylammonium chloride), creosote, and toulene- and waterborne copper naphthenate. The efficacy of CCA, and of water- and oilborne copper naphthenate against a brown-rot fungus (Postia placenta), a white-rot fungus (Trametes versicolor), and a soft-rot fungus (Chaetomium globosum) was also determined using sapwood blocks in agar block decay tests. Substantial differences were found between heartwood and sapwood testability. Full-cell impregnation resulted in sapwood samples being thoroughly penetrated and consistently treated to retentions of 30 to 40 pcf (lb. solution/ft.3 wood). Preservatives penetrated heartwood only about 3 mm transversely and 15 mm longitudinally. Retentions ranged from 5 to 15 pcf. On an equivalent copper loading basis, the oilborne copper naphthenate was more effective than the waterborne formulation against white- and soft-rot fungi. CCA protected maple sapwood against brown- and white-rot fungi at low retentions, 0.1 percent copper weight/weight. Similar to past work, however, higher loadings were needed for soft-rot protection.

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