Depletion and Redistribution of Boron in Bundles of Commercially Treated Lumber Exposed to Artificial and Natural Rainfall

IRG/WP 08-30474

M E Mankowski, M J Manning

The depletion and redistribution of boron from stacks of Southern Yellow Pine lumber pressure treated with disodium octaborate tetrahydrate (DOT) and exposed to artificial and natural rainfall was examined. When the lumber was exposed to periodic simulated rainfall, 5.7-8.1% of the measured boron present leached from the lumber after exposure to over 300 mm of rainfall. In tests which exposed boards to natural rainfall for 6-8 months, an estimated 9.7-14.9% of the calculated boron migrated from the stacks. In both tests, the majority of the exposed lumber retained boron levels at or above the AWPA standard suitable for exposure to Formosan termites of 4.48 kg/m3. In a harsher exposure test, DOT treated boards were submerged for over one month and representative boards were periodically removed to examine changes in boron levels. After 18 days of submergence a significant amount of boron had depleted from the test lumber. However, subsequent samplings showed lower levels of boron leached from submerged test boards. These results demonstrate that depletion of boron from dimensional lumber exposed to moderate amounts of liquid water should not result in significant decreases to boron levels in the wood.


Keywords: borates, depletion, DOT, leaching, rain tests, artificial weathering, natural weathering

Conference: 08-05-25/29, Istanbul, Turkey


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