Green finger jointing is increasingly becoming a proven possibity with three main technological processes, the New Zealand Greenweld process, the US soybean-based adhesive process and the US soybean-based adhesive process by assessing drying degrade and mechanical performance of green-glued finger-jointed material after drying. The urethane-based adhesive process was studied in a previous project. Overall, we did not observe performance differences between the Greenweld and the soybean-based adhesive processes. This was to be expected since they are both phenol resorcinol formaldehyde types of adhesives. Thus, the process choice should be made based on other considerations than mechanical performance, such as economical or procedure preferences. In comparison with the polyurethane adhesive studied before, it appears obvious that more stress concentration is present at the joint after drying because of the failure modes observed. However, with long term use, this product (the urethane-based adhesive) still needs to be studied because it is less known than the two other phenol-resorcinol-formaldehyde based processes. The results also demonstrate that green finger-jointing material, such as black spruce and balsam fir, could at least be used to produce stud grade lumber.
There are six species of poplar native to Canada's forests. One of the most abundant and widely used of the species is the aspen poplar (populus Tremuloides). Aspen has become the most desirable species for the production of oriented strandboard (OSB). Certain sections of Alberta and British Columbia have considerable stands of aspen. The aspen stands also contain varying amounts of balsam poplar (populus balsamifera) and black cottonwood (populus trichocarpa) and various hybrids of the three species. Forintek Canada Corp's Technical Advisory Committee (TAC) was asked by the B.C.Ministry of Forests to establish whether cottonwood could be a suitable furnish for the production of OSB, since it represented a sizeable potential resource in British Columbia. The poplar species are loosely identified by several names and to confirm the actual species we were referred to Mr.Bob Brash, District Manager, Dawson Creek Forest District. Mr.Brash confirmed that the species in question was in fact balsam poplar (populus balsamifera). Balsam poplar is also known as black poplar and balm poplar. An extensive literature search was conducted on the use of balsam poplar/cottonwood in the production of OSB. The literature review and a summary are reported here.
Discolourations of hem-fir, usually called hemlock brownstain, have become an economically important problem with the move towards increased kiln-drying of the wood species mixture and added-value products in which discolourations cannot be tolerated. These discolourations, clearly different from sapstain, can occur in several types and intensities and are a serious problem in high-value markets. Because little is known about their causes means for their control are still unavailable. Therefore fundamental research was initiated to elucidate the biology and chemistry of hemlock brownstain and to suggest control measures. A post graduate student was hired to undertake laboratory and field work as part of a Ph.D. program. The thesis subject was "the role of microorganisms in the phenomenon of hemlock brownstain". The thesis covers: a literature review; laboratory work to locate the stain and define its nature; a storage study of logs and lumber to monitor progress in development of brownstain; fungal isolation work and sap characterization studies; in vitro production of hemlock brownstain in wood and sap; and additional laboratory experiments to determine what factors influence the formation of the brownstain. In addition to the thesis research the role of bacteria in the formation of the stain was investigated in the laboratory and the ability of various chemicals, including fumigants, to prevent the stain was tested in small-scale field test. This report provides an overview of the findings and provides recommendations for future work. The experiments clearly demonstrated that a non-specific microflora can produce brownstain which led to the hypothesis that microorganisms could be involved in hemlock brownstain. Based on our knowledge of the coastal sawmilling industry a strategy of minimizing fungal infection and rapid handling of the tree breakdown into final wood products could probably be the best approach to help reduce the problem. In terms of future work we recommend that work to understand the mechanism of DDAC in mitigation of the browning take precedence in future work on hemlock brownstain.
This publication characterizes nine commercial tree species of Alberta. Included are descriptions of the range and volume of each species, their wood properties, and present and potential manufacturing uses.
This report evaluates a new fluctuating pressure treating process, with a small pressure variation, that could be easily implemented into a treating plant with a control value. Coastal western hemlock being a relatively difficult species to impregnate was chosen as a suitable test species. Incised and unincised hemlock was used to relate to present industry practices.
A software, by which virtual 3-D subalpine fir (Abies lasiocarpa [Hook] Nutt) logs can be re-created, visualized, and theoretically sawn an infinite number of times, was developed. The software also facilitates obtaining data for determining quantitative variation of clear wood, wet-wood, and knot patterns within the tree stems.
Results based on the quantitative calculations showed that there are two general patterns of wet-wood within the sub-alpine fir stems. The first pattern is called wet-pocket and the second pattern is called wet-streak. Wet-streak patterns are generally confined to the medullary-inner heartwood regions in the outer heartwood and heartwood-sapwood transition zones of the tree stems, mostly associated with dead knots. Wet-pocket patterns consist of portions occurring in mid regions in close proximity to the base and regions mostly around partially dead knots of the tree stems. Both wet-wood patterns usually converge at the nodes and extend along the branch axes, forming a connection with the exterior boundary only around branches.
Numerical analysis of the results showed that the volume of both types is more prevalent in the lower-stem regions, becoming less prevalent towards the living crown. The radial extension of wet-wood types with radial distance from the tree centre was variable, with a maximum diameter of 22 cm. Both wet-wood volumes increased with increasing tree age and diameter class independent of age. However, the percentage of total wet-wood volume decreased with increasing DBH, increased stem height and showed no clear trend with age class. Total amounts of wet-wood ranged up to 27 per cent in individual stems. A weak relationship was found between dead knot-pattern and wet-streak pattern volumes, while a moderate high relationship was found between partially dead knot and wet-pocket volumes. A weak relationship was found between external tree characteristics and both wet-wood distributions.
As a result, some promising trends emerged for a better understanding of wet-wood and knot pattern variations as influenced by tree stem locations, DBH, and age. The developed software may offer a compelling technique for assisting subalpine fir log processing decisions. However, the destructive data collection method used in this study is “error-prone”. Therefore, an interesting alternative would be the use of more accurate non-destructive scanning techniques, such as CT-scanning, to verify the trends identified here through more deliberate sampling at other forest sites. A new study is already underway to meet this need.
Commercial thinning at a relatively young age will result in changes not only to log size but to wood quality as well. One important change in the thinnings will be the increased proportion of juvenile wood relative to mature wood. In western hemlock (Tsuga heterophylla (Raf.) Sarg.), where the difference in wood density between juvenile wood and mature wood is relatively large, a higher proportion of juvenile wood can result in reduced lumber strength and lower pulp yields. Another change will be seen after thinning in the remaining standing trees; late-release growth pattern changes in terms of grain. The present report summarizes the results of X-ray densitometric analysis of 50-year-old western hemlock trees thinned from 1656 and 956 stems/ha plots, and amabilis fir (Abies amabilis (Dougl.) Forbes) from the 956 stems/ha plot. Results were compared to old-growth reference data, and to a recently completed basic wood properties study of 90-year-old western hemlock (Jozsa et. al., 1997).
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.