The effect of pressure on retention and bending properties of copper naphthenate and CCA type C treated hardwoods

The objective of this study was to investigate the effect of the pressure l evel on retention and bending strength of same northern hardwood species af ter preservative treatment. Samples of red maple, sugar maple, beech, and r ed oak were pressure-treated with waterborne chromated copper arsenic (CCA) type C or with oilborne copper naphthenate (Cu-N) at four pressure levels: 0.69, 1.03, 1.38, 2.07, and 2.76 MPa. At a pressure level of 0.69 MPa (200 psi) for 2 hi retentions of 4.5 kg/m(3) elemental copper from copper napht henate and 10 +/- 7 kg/m(3) total oxides from chromated copper arsenate (CC A) were achieved for maples. The pressure level did not affect the retentio n of Cu-N in red maple, sugar maple, and red oak: the same observation was made for CCA in maples. A pressure level of 2.76 MPa was needed to obtain a 7.5 kg/m(3) CCA retention and 1.08 kg/m(3) copper metal in Cu-N-treated be ech. Copper naphthenate treatment did not affect the bending strength. whil e CCA-treated samples exhibited a reduced bending strength between 0 and 33 % depending on the species, pressure level, and preservative type.