The Effect of Pressure on Retention and Bending Properties of Copper Naphthenate and CCA Type C Treated Hardwoods


  • D. Pascal Kamdem
  • Poo Chow


CCA, Cu-N, copper naphthenate, hardwood, retention, pressure treatment, bending


The objective of this study was to investigate the effect of the pressure level on retention and bending strength of some northern hardwood species after preservative treatment. Samples of red maple, sugar maple, beech, and red 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 h, retentions of 4.5 kg/m3 elemental copper from copper naphthenate and 10 ± 2 kg/m3 total oxides from chromated copper arsenate (CCA) were achieved for maples. The pressure level did not affect the retention 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/m3 CCA retention and 1.08 kg/m3 copper metal in Cu-N-treated beech. Copper naphthenate treatment did not affect the bending strength, while CCA-treated samples exhibited a reduced bending strength between 0 and 33% depending on the species, pressure level, and preservative type.


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