Patricia K. Lebow

Penetration of Boron from Topically Applied Borate Solutions

Borate penetration relies on diffusion when borate and glycol-borate preservatives are applied to the surface of wood. This study evaluated the extent of borate penetration in framing lumber as a f...

Long-Term Durability of Pressure-Treated Wood in a Severe Test Site

Improved estimates of the long-term durability of treated wood products are needed to guide choices about construction materials and allow estimates of design life. This report summarizes the long-term decay and insect resistance of treated wood post and lumber specimens placed in ground contact at a test site of the U.S. Department of Agriculture, Forest Service, Forest Product Laboratory in southern Mississippi. Posts treated with relatively low levels of creosote had an estimated durability of 54 years, and slightly less durability was observed in creosote-treated lumber. Pentachlorophenol-treated posts exhibited durability in excess of 60 years, whereas lumber specimens treated to standard ground-contact retentions had no failures after 39 or 45 years. Posts treated with low retentions of copper naphthenate had an estimated 65-year longevity, but lumber specimens treated to higher retentions of copper napththenate had lower average lives of 27 to 30 years. Low-retention ammoniacal copper arsenate (ACA) posts had an estimated durability of 60 years, whereas stakes treated to retentions of 8 kg/m3 (0.5 lb/ft3) or greater with ammoniacal copper zinc arsenate (ACZA) or ACA have had no failures after 30 and 60 years, respectively. Posts treated with a range of retentions of chromated copper arsenate (CCA-C) have had no failures after 35 years, and stakes treated with CCA-A, CCA-B, or CCA-C to retentions above 7 0 kg/m3 (0.43 lb/ft3) have had no failures after 60, 61, and 40 years, respectively. As a whole, the post and lumber specimens indicate an expected durability of over 50 years for creosote-treated wood and over 60 years for wood treated with pentachlorophenol, copper naphthenate, ACZA, or CCA. Comparison of the results from this site to reports from other locations suggests that these results might underestimate the potential durability in more moderate exposures. In relating these findings to treated commodities, it should be noted that these test specimens have not been subjected to the same mechanical loads or wear and tear associated with in-service structures.

Boron Diffusion in Surface-Treated Framing Lumber

Abstract The extent of boron penetration in framing lumber treated by spray applications during construction is not well quantified. This study evaluated the effect of formulation and concentration...

Effect of fungal competition on decay rates in bicultured soil bottle assays

Abstract For decades, wood scientists and preservative formulators have employed the monocultured soil bottle assay to test efficacy of wood treatment in the laboratory as a rapid predictor of field performance. This study examines the effects of bicultured soil bottle assays on the decay by common wood decay fungi. Mycelial interactions were noted in early stages of colonization. With only two exceptions, a single fungus was apparent in each soil bottle, indicating dominance. The dominant fungi were not always the most efficient wood rots, and the rot type, white or brown, did not affect the dominance outcome on the preferred wood type.

Fifty-Year Durability Evaluation of Posts Treated with Industrial Wood Preservatives

Abstract Long-term durability data are needed to improve service life estimates for treated wood products used as critical structural supports in industrial applications. This article reports the durability of longleaf pine (Pinus palustris) posts pressure treated with ammoniacal copper arsenate (ACA), chromated copper arsenate (CCA), creosote, or pentachlorophenol and exposed for 50 years in southern Mississippi. During inspections, posts were subjected to a pass/fail evaluation by applying a load to the top of the post. No failures occurred in any of the 125 posts treated with CCA or in any of the 75 posts treated with pentachlorophenol. Three of 25 ACA-treated posts and 5 of 25 creosote-treated posts failed. Estimated times to 50 percent failure in the ACA- and creosote-treated posts were calculated as 96 and 78 years, respectively. The estimated years to failure for the CCA- and pentachlorophenol-treated posts could not be calculated because of the lack of failures but presumably would be greater than...

Effect of Treatment Pressure on Treatment Quality and Bending Properties of Red Pine Lumber

Although higher treatment pressures have the potential to improve preservative penetration, higher pressures may possibly result in greater reduction in mechanical properties. The present study eva...

Northeastern United States species treated with copper-based preservatives: Durability in Mississippi stake tests

This paper reports on the ground-contact durability of lesser-used wood species of the northeastern United States after treatment with copper-based preservatives. Stakes (19 by 19 by 457 mm) cut from balsam-fir (Abies balsamea), eastern hemlock (Tsuga canadensis), eastern spruce (mixture of Picea glauca, Picea mariana and Picea rubens), red maple (Acer rubrum) or eastern white pine (Pinus strobus) were treated with one of four concentrations of chromated copper arsenate type C (CCA-C), copper citrate (CC), alkaline copper quat type C (ACQ-C) or copper azole type A (CBA-A) and placed into the ground at a test site in southern Mississippi. Similarly treated southern pine (Pinus spp.) stakes were included for comparison. The stakes were rated for decay and termite attack after 1, 2, 3, 4, 5, 8, 10 and 12 years. Eastern white pine and incised eastern hemlock and balsam-fir had durability similar to southern pine when treated with CCA or the other copper-based preservatives. Eastern spruce was less durable than the other softwood species, apparently because of low preservative uptake. Red maple had the least durability at all retentions and for all preservatives. This study indicates that several northeastern softwoods can be adequately durable when pressure-treated with CCA-C or copper-based preservatives.