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 transparent coating with long-term performance could help wood maintain its share of residential markets against material substitution and potentially expand markets in recreational property and non-residential buildings. While transparent coatings can be made reasonably resistant to UV some UV likely penetrates to the wood and by necessity clear coatings are transparent to visible light. Visible light can also cause damage over the long term thus the underlying wood needs additional protection. Four novel UV protection systems were tested as pre-treatments on uncoated wood and under three coatings, a water-based film forming coating, a water-based acrylic varnish and a solvent based water repellent. Samples were exposed to natural weathering facing South at 45° at a test site in Gulfport, Mississippi, in collaboration with the USDA Forest Products Laboratory. The test material was inspected every six months for discolouration, mold and stain, coating water repellency, flaking, erosion and cracking and substrate condition. After 24 months exposure, coatings over the combination of UV absorber and lignin stabilizer identified by Stephen Ayer were performing better than the same coatings applied over the combination recommended by Ciba and coatings over both pre-treatments were performing substantially better than controls with no pre-treatment. Projection of fitted curves beyond the data appears to indicate that pretreatment may double the life expectancy of the coating. There was no consistent effect of the synergists on either combination at this time.
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.
Mould and stain became troublesome problems on lumber manufactured at a coastal British Columbia sawmill, and the difficulties were suspected to be a fault of the mill's antisapstain treatment. Forintek technical staff visited the sawmill and planer mill and used two procedures to gather assessment. Firstly, boards were pulled from spray box chains after spray treatment and one-inch square samples were punched from four faces of these boards for chemical analysis of DDAC, one of the active ingredients in the formulation being used. With a large number of samples, this procedure quantitatively assessed DDAC retention levels at points along boards. Secondly, fluorescent dye was added to the spray solutions and special paper strips were stapled along the length of boards prior to treatment in the spray box. The paper strips were then retrieved for examination under ultraviolet light. This procedure is largely a qualitative one, showing the pattern of spray coverage over the whole board. Liquid samples of the treatment solutions were taken from both the sawmill and planer cross chain day tanks to determine their DDAC concentrations.
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.
