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
Wood failure evaluation is the key criterion for predicting the long-term durability of plywood. At present, the conventional visual method for plywood wood failure evaluation is slow and subjective. Evaluations can be influenced by factors such as: room lighting, wood species, sample treatment, and readings from prior samples. An automated wood failure evaluation system using image analysis techniques could potentially be programmed to consider all the variables and respond with consistent wood failure values regardless of the machine operator's experience level. This report describes the results of a six-month study in which a system for automated plywood wood failure determination was compared with conventional visual wood failure evaluation. It was built upon research undertaken in the 1996/97 year in which the feasibility of the approach was initially established. In the research reported previously, a colour optical imaging system was assembled and suitable wood failure algorithms were compiled with promising results. The imaging system was 100 % effective in reproducing sample values. The data were discussed with the project liaisons and a three-month comparison with Canply readings was suggested. In this study, machine evaluation of 4,150 samples was compared with readings of monthly plywood mill quality control samples. The sampling was designed to include all British Columbia plywood mills and all categories of commercial plywood production. The differences in average values for wood failure between human and machine evaluation were found to be less than plus or minus 5% in the majority of cases. In addition, 93 % of ‘set average' readings fell in the plus or minus 10% range of deviation expected of human wood failure readers. Agreement on readings of individual samples within each set was not quite as good with 72% falling in the plus or minus 15% range.
This report describes some of the background and results of work done to date on second-growth western hemlock basic wood properties at Forintek Canada Corp. The B.C. Ministry of Forests (BCMOF) Research Branch, UBC Forestry Faculty and PAPRICAN were the other cooperating agencies on this project and they investigated live crown/tree growth relationships, strength properties of small clears, and pulping properties, respectively. Properties that were assessed by Forintek, both within and between trees include: relative density of wood, shrinkage, moisture content and relative proportion of heartwood-sapwood, bark thickness, content and distribution of compression wood, incidence and degree of spiral grain, incidence and severity of brown stain, and strength properties of small cleear bending samples. Naturally grown 90-year-old western hemlock stands represent much of the emerging timber supply in the B.C. coastal forest region. Information characterizing the commercial quality of this resource is needed now to support processing and marketing decisions and for product promotion. In addition, the BCMOF and industry members are making stand management decisions today which will determine the future quality of western hemlock. We can reduce the risk of making wrong investment decisions by providing information on how different growing conditions (e.g., biogeoclimatic zone, site, stand density, thinning) affect second-growth wood quality.
The first paper, Understanding Biodeterioration of Wood in Structures, provides an overview of the subject matter and refers to a selection of textbooks for more detail. It provides some essential background on wood structure and composition, the range of wood-inhabiting organisms and their effects on wood. The colonisation sequence, the conditions required for decay, and the rates of growth and strength loss are covered in some detail. The second paper, Moisture Problems in Vancouver Condominiums reviews the background to the recent epidemic of decay problems in southwestern B.C. and Forintek's short-, medium- and long-term response. In the short term, Forintek has been assisting in the work of the Building Envelope Research Consortium (BERC) designed to understand and deal with these problems. In the medium term, we have developed a combination of safe low-level chemical treatments which will provide OSB with the same fungal resistance as Douglas-fir faced plywood. This paper also describes the long-term project Decision Aids for Durable Wood Construction.
The effects of different pressing variables were evaluated for the manufacture of hog fuel board made from western hemlock. In general, the hog fuel boards made at higher temperature and pressure exhibited better dimensional stability and durability properties. Pressing time was reduced with temperature ranging from 20 min at 260 C to 4 min at 315 C. It was demonstrated that good quality hog fuel boards could be produced using a high wood content of 65%. In all cases, the western hemlock hog fuel boards showed an average thickness swelling less than 10% after a 2-hour boil test. After the same treatment, OSB shows 50% thickness swelling and particleboard disintegrates. Preliminary results for bark / hog fuel boards made from three eastern species, white spruce, balsam fir and jack pine showed the boards exhibited excellent dimensional stability and durability properties. In the interests of furthering the preliminary market and economic feasibility investigations of bark board and in co-operation with Dr. A. Kozak and his 4th year marketing class (Dept. of Wood Science, UBC), exploratory analyses were done on four potential end uses. These were flooring, floor underlayment, roof shingles and furniture / cabinets.
Research was carried-out to investigate the feasibility of electrostatically applying PF powder resin to OSB furnish to improve resin distribution and thereby improve panel properties. Research elsewhere has shown that resin distribution is an important factor affecting panel properties including internal bond strength and thickness swell. It was theorized that electrostatic charging would distribute resin more uniformly on strands compared to conventional application techniques and would help to strengthen the bond between resin and strands thereby minimizing resin losses and allowing for greater levels of resin to be retained on OSB furnish. Small-scale tests were conducted in Forintek's Vancouver laboratory followed by pilot plant tests at the Alberta Research Council (ARC) which involved electrostatically charging resin and aspen furnish in a pilot plant blender. Lab results showed that the average amount of resin retained by strands (retention) increased with electrostatic application compared to control applications. During pilot plant tests, image analysis results showed that resin coverage increased using electrostatics. Also, the coefficient of variation in resin coverage was lower for electrostatic applications compared to the controls. However, contrary to previous research findings, test panels made from electrostatic and control batches in a pilot plant did not show any significant differences in internal bond and thickness swell properties. Electrostatic application of powdered PF resin does not appear to sufficiently improve resin distribution in aspen to affect panel properties. Although pilot plant results were not promising, lab tests have shown that electrostatic application techniques are sensitive to material properties and that other wood species may be more suitable for charging than aspen. Further research will be continued at Forintek's eastern lab in the 1998/99 year to investigate electrostatic application of resins to mixed hardwood species.