ISSN: 1945-7553
CODEN: JTEVAB
Published Online: 21 January 2010
Page Count: 5

Water Vapor Sorption Isotherms for Southern Pine Treated with Several Waterborne Preservatives

Zelinka, Samuel L.
Materials Engineer, Forest Products Laboratory, U.S. Forest Service, Madison, WI

Glass, Samuel V.
Research Physical Scientist, Forest Products Laboratory, U.S. Forest Service, Madison, WI

(Received 18 August 2009; accepted 9 December 2009)

Abstract

Equilibrium moisture content (EMC) was measured over a range of relative humidities at 22.5°C to determine whether certain wood preservatives increase the hygroscopicity of southern pine (Pinus sp.) The treatments studied were alkaline copper quaternary (ACQ) at a retention of 6.6 kg⋅m⁻³, chromated copper arsenate (CCA) at 6.9 kg⋅m⁻³, and disodium octaborate tetrahydrate (DOT) at 3.8 kg⋅m⁻³ (equivalent to 2.6 kg⋅m⁻³ as B₂O₃). All treatments examined increased the EMC at relative humidities above 60 %. Wood treated with DOT was the most hygroscopic. At high relative humidities, the ratio of the EMC of ACQ-treated wood to CCA-treated wood was 1.08. It is unlikely that the higher corrosiveness of ACQ compared with CCA is due to this slight increase in hygroscopicity.

Keywords:
equilibrium moisture content (EMC), water vapor sorption, preservative treatments, chromated copper arsenate (CCA), alkaline copper quaternary (ACQ), borates, disodium octaborate tetrahydrate, corrosion

Paper ID: JTE102696
DOI: 10.1520/JTE102696
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