As a result of the activities of the mountain pine beetle which carries with it staining fungi, increasing amounts of bluestained wood are entering the marketplace. Bluestain is a visual defect caused by fungi that colonize the sapwood of trees, logs or lumber. Although typical bluestain fungi do not significantly impact mechanical properties, the wood is less desirable for appearance-grade applications. Bluestain is also associated with increased permeability, which could make it more suitable for preservative treatment. Methods are needed to identify stained lumber in the mill either to remove it from appearance grades or select it for preservative treatment. Detection of bluestain can be made visually, since it is an appearance grade defect. In industry, RGB colour coordinates are used to identify bluestained lumber. However beetle-affected wood from advanced grey stage trees is also anticipated to contain decay. Although the present research focuses on detecting bluestain only, a method of detecting both decay and stain would be preferable. Technology for detection of decay in pulp chips had been developed by Paprican and work is underway to evaluate its effectiveness on lumber.
The present research describes efforts to develop an automated spectroscopic system for identification of bluestained lumber. A large visible/near infrared spectrometer from FPInnovations – Paprican Division was used to scan motionless bluestained and clear 2 x 4” lumber on four sides. These spectra were used to model observed visual ratings of bluestain intensity using multivariate statistical methods. A Partial Least Squares (PLS) model developed from the top and bottom spectra was able to differentiate degree of staining. A PLS model from the side spectra was not able to differentiate stained and clear wood.
In view of the long-standing nature of the Canada-U.S. softwood lumber dispute, this literature review examines opportunities for softwood products that are currently not affected by the dispute. This includes non-commodity softwood products for the U.S. market and softwood lumber opportunities in the domestic Canadian market, Asia and Europe.
Alberta Alliance Project No. 5130-05 pertaining to softwoods - Utilization; softwoods - Markets
Seven B.C. species, namely, interior Douglas fir, coastal second growth Douglas fir, western larch, lodgepole pine, western white spruce, trembling aspen and white birch were evaluated for their laminating properties using different adhesive formulations and pressing conditions.
Using optimized gluing and pressing conditions, six of the B.C. species showed excellent bond quality when laminating with radio-frequency (RF) heating and either cross-linked polyvinyl acetate (PVAC) or phenol-resorcinol-formaldehyde (PRF) adhesive. These laminates easily passed the shear block wood failure requirement in the ASTM-D-2559 standard and the delamination requirement in the ASTM-D-1101 standard. Because white birch which has a high density showed the highest block shear strengths for the optimum PRF adhesive formulation, this species showed the lowest average percent wood failure of the seven B.C. species and did not meet the ASTM-D-2559 wood failure requirement of 75%.
Using conventional platen pressing at 20 or 25°C, laminates were prepared with different PRF adhesive formulations and the seven B.C. species. Using an optimized PRF adhesive formulation, the laminates for the seven BC species met the above ASTM standard requirements for wood failure and delamination.
Overall, the percent wood failure was higher for the laminates made at 25°C indicating more resin cure. Hence, for laminates made with the optimum PRF formulation, PRF-C, the average percent wood failure for western larch at 20°C was 78% compared to 98% at 25°C.
Laminated products - Manufacture - British Columbia