A field test of six millwork preservatives has been ongoing for twenty years, using a simulated window corner, or "Y-joint", as the test unit. Three preservatives provided excellent protection to white pine and white spruce: 5% pentachlorophenol in varsol, phenyl mercury oleate in varsol, and 0.75% oxine copper in varsol.
A field test of six millwork preservatives has been ongoing for 25 years, using a "Y-joint" as the test unit. Three preservatives provided excellent protection to white pine and white spruce: 5% pentachlorophenol in varsol, phenyl mercury oleate in varsol, and 0.75% oxine copper in varsol.
An accelerated decay test was set up to compare the performance of CCA-treated needle-incised white spruce and lodgepole pine heartwood with end-matched conventionally-incised material. Short lengths of 2 x 4 and comparable untreated material were installed in a warmed soil bed in the open air. After 12 years of accelerated exposure (equivalent to 15 years' natural exposure), all the treated material - spruce and lodgepole pine, needle and conventionally incised - was almost completely sound with minor patches of surface decay. In contrast, both the untreated spruce and the untreated lodgepole pine heartwood had failed due to decay. The performance of needle-incised and conventionally-incised lumber has been very similar in both species.
Preservation - Incising - Tests
Picea - Preservation
Pinus contorta Dougl. var. latifolia - Preservation
As a result of its potential as an added-value, environmentally acceptable, high performance wood product, borate-treated lumber has attracted the interest of the Canadian forest products industry (Byrne 1990). One of the potential markets for borate-treated wood in Europe and North America is millwork. Currently millwork manufacturers use light organic solvent preservatives to provide durability to their products but there are a number of reasons why this situation may change in the near future. There are increasing pressures on uncontrolled emission of volatile organic solvents from treated wood and public concerns regarding some of the active ingredients now in use (Orsler and Holland 1993). The use of borate-treated wood eliminates both of these problems and may provide some additional advantages by eliminating batch processing in the manufacture of joinery. The one factor which is likely to have the greatest impact on the performance of borate-treated millwork is the mobility of the boron. Borate-treated wood is currently approved for use in exterior exposure in New Zealand provided it has a three-coat paint finish. Nevertheless there is concern outside New Zealand that redistribution of boron within the treated wood could lead to localized depletion and decay. An L-joint test of borate-treated wood was set up by Forintek to determine whether preservative depletion and subsequent decay is likely to be a problem. This report describes the performance results of this trial after six years and compares borate content of the L-joints initially and after five years exposure.
Methods for the analysis of boron in wood were reviewed and one, a method in which base titration of a mannitol/boron complex is done, was chosen for possible routine use. Method parameters were tested and the stages were modified to arrive at a routine which can determine boron content in wood within 5% accuracy. Hot water leaching of chip samples, 2.54 x 2.54 cm x 2 to 3 mm thick, of wood which has been given borate/antisapstain treatment is better than 95% efficient within four hours; this is as efficient as a ten-cycle extraction on a soxhlet apparatus. Using an automatic titrator, analysis for boron is done by titrating a mannitol complex of the boron in the extract. The simplicity, low expense, speed, and accuracy of this routine give it the advantage over several other methods. The aqueous extracts of wood, the mannitol reagent, and secondary components of boron treating formulations can all add to the apparent boron content of the wood sample; these factors are variable but generally total about 8 *g boric acid equivalent per cm2 of wood surface. The method is also suitable for the analysis of boron in heavily (preservative) treated wood.
Compilation of reports. 1. Performance of treated lumber against termites after 11 years of test in Ontario. 2. Performance of borate-treated wood against subterranean termites under above-ground protected conditions in Canada
North American subterranean termites have become a major factor limiting the service life of wood products in southwestern Ontario. If preservative treatment can be demonstrated to prevent termite attack, the market for wood products could be maintained and expanded. With the assistance of the town of Kincardine, Ontario, Forintek set up a ground-contact termite test site in 1988. The material used included red pine, lodgepole pine, jack pine, hemlock, white spruce and mixed spruce-pine-fir. The preservatives were chromated copper arsenate (CCA-C), ammoniacal copper arsenate (ACA) and ammoniacal copper quat (ACQ). Both incised and unincised lumber was included in the tests where possible. Also used was CCA-treated hem-fir plywood.
The material was inspected in the summer of 1999. Treated material was generally performing well, with some pieces starting to show signs of superficial surface feeding, or cosmetic damage. Some samples that had lower assay retentions and preservative penetrations showed more than just trace nibbles and termites appeared to have actually penetrated through the outer treated zone. It appeared that termite entry occurred in areas on the wood surface where defects may have facilitated such entry. Material that came close to meeting CSA O80 standards for ground contact generally suffered only minor damage.
Forintek expanded the test in 1996 to include borate-treated material above-ground, protected from rain. This method simulates the sillplate, or dodai, used in traditional Japanese housing construction. The material included hemlock and amabilis fir lumber treated with borate and chromated copper arsenate (CCA). When it was inspected in the autumn of 2000, the treated material was generally found to be performing well, with some pieces starting to show signs of superficial feeding or cosmetic damage. Attack was moderate on untreated controls.
A field test of simulated decking under natural weathering conditions was established to compare the dimensional stability in service of amabilis fir (Pacific silver fir) and western hemlock. After 30 months of exposure, incised and CCA-treated amabilis fir outperformed western hemlock in terms of bow, crook, and cross-checking associated with compression wood.
Information from Forintek's field-testing program provides technical support to marketing and helps Canadian forest products companies access domestic and export markets for which Standards compliance is important. Forintek is virtually the only independent source of commodity and preservative performance data for the Canadian Standards Association O80 Technical Committee on Wood Preservation. We are also one of the very few sources of such data, with respect to Canadian wood species, for the American, European, and Japanese Standards. All changes to Standards require supporting data. Our field test information thus assists in marketing Canadian wood products.
A range of commercially available natural finish products were exposed to natural weathering at test sites in Vancouver, B.C. and Gulfport, Mississippi. One of the pre-treatments evaluated under these finishes was chromated copper arsenate (CCA) pressure treatment. After 28 months in test, the finishes over CCA-treated wood were subjected to a wipe test to assess their ability to seal in arsenic. Film-forming finishes provided a good barrier against leaching, while penetrating stains were less effective, although all finishes reduced dislodgeable arsenic compared to unfinished CCA-treated wood.
