Efficacy of a borax-copper preservative in exposed applicationsAuthor(s): Stan T. Lebow; Patricia K. Lebow; Bessie M. Woodward; Steven A. Halverson; William Abbott; Michael M. West
Source: Research paper FPL-RP-655
Publication Series: Research Paper (RP)
Station: Forest Products Laboratory
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This study evaluated the ability of pressure treatments with a borax–copper (BC) preservative to protect wood exposed above ground or in contact with the ground. Stake testing indicated that the 2.3% and 4.7% BC concentrations were fairly effective in preventing decay in Wisconsin but were not effective in protecting stakes exposed in Mississippi. The 1.4% and 2.3% BC concentrations effectively protected decking specimens exposed for 5 years at the Wisconsin test site. Assay of stakes at the Wisconsin site indicated that over 90% of boron in the below-ground portion of the stakes was lost within the first year, leaving copper as the sole biocide. Assay of the decking specimens after 4 years of exposure indicated that between 30% and 45% of copper and 80% and 95% of boron was lost from the BC-treated decking specimens. These copper losses were greater than those found with the laboratory simulated rainfall study, which indicated that 5% to 6% of copper was lost from the 1.4% and 2.3% BC treatments after the equivalent of 1 year of rainfall. Boron losses of 45% to 55% were noted with 1 year’s equivalent of simulated rainfall. This series of studies indicates that the efficacy of BC as a pressure-treatment preservative in exposed applications is a function of copper retention.
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CitationLebow, Stan T.; Lebow, Patricia K.; Woodward, Bessie M.; Halverson, Steven A.; Abbott, William; West, Michael M. 2009. Efficacy of a borax-copper preservative in exposed applications. Research paper FPL-RP-655. Madison, WI: USDA-Forest Service, Forest Products Laboratory. 11 p.
KeywordsPreservatives, copper borates, stake tests, leaching, borax, copper, preserved wood, evaluation, wood preservation, wooden buildings, borax-copper, pressure-treated wood, above-ground, ground-contact, durability, leaching
- Ground-contact durability of wood treated with borax-copper preservative
- Estimating preservative release from treated wood exposed to precipitation
- Laboratory immersion method for accelerated prediction of preservative leaching from pressure-treated wood exposed to precipitation
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