Le Ministère des Ressources naturelles du Québec (MRN) et les membres de l’industrie des bois feuillus de Forintek ont fortement recommandé l’implication de Forintek dans le développement d’un logiciel d’optimisation du tronçonnage des tiges de bois feuillus. Des évaluations préliminaires ont démontré que l’optimisation du tronçonnage des tiges de bois feuillus pouvait augmenter jusqu’à 30 % la valeur des produits.
Suite à la demande du MRN et des membres de Forintek, FERIC et Forintek ont présenté des projets de recherche sur l’optimisation du tronçonnage des tiges de bois feuillus visant l’élaboration d’une stratégie de tronçonnage pour maximiser la valeur des produits finis et le développement d’un logiciel de formation pour améliorer l’efficacité des responsables du tronçonnage des tiges de bois feuillus.
Forintek dispose d’une importante banque de données renfermant plusieurs études de rendement complétées dans des scieries de bois feuillus. Cette banque de données a servi à développer une matrice de la valeur des produits selon la qualité des billes et des billons pour deux essences, soit l’érable à sucre et le bouleau jaune, qui y étaient représentés en quantité suffisante.
La grille de classification utilisée est celle de Petro parce qu’elle s’appuie sur des recherches sur la qualité des billes de bois franc du Laboratoire des produits forestiers de l’Est et est aussi en conformité avec les rapports publiés par le Service forestier des États- Unis. La grille de classification du MRN pour les bois feuillus a aussi été intégrée au logiciel vu son utilisation par l’ensemble des scieries du Québec possédant des CAAF.
Toutes les données de rendement en volume et en valeur des produits et des sous-produits de la base de données de Forintek ont servi à monter un chiffrier Excel pour calculer automatiquement la valeur des produits pouvant être générés à partir d’une solution de tronçonnage proposée. On peut se servir de cet outil pour comparer le rendement en valeur de plusieurs solutions théoriques pour identifier celle qui maximisera la valeur des produits. Pour faciliter l’utilisation de cet outil de travail, nous avons programmé un Microflex, soit un petit ordinateur très robuste, pour maximiser l’efficacité lors des travaux terrain.
Une étape importante pour l’optimisation du tronçonnage des tiges de bois feuillus a été complétée dans le cadre de ce projet de recherche. Les industriels et les manufacturiers possèdent maintenant un outil qui génère la valeur des produits et des sous-produits de l’érable à sucre et du bouleau jaune selon deux grilles de classification des billes : celle de Petro et celle du MRN. Tous les intrants dans la feuille de calcul peuvent être modifiés ce qui permet à l’utilisateur d’y intégrer ses propres qualités de billes et les résultats de tests de rendement en volume et en valeur effectués à l’interne.
L’établissement de la valeur des billes selon la qualité servira à la formation des préposés au tronçonnage, à établir des priorités de tronçonnage mais aussi à dicter le coût maximum pour l’achat des bois ronds. Combiné à un système de lecteurs capables de localiser les défauts sur le tronc des arbres, un manufacturier pourrait réaliser l’optimisation du tronçonnage feuillu
Une copie du rapport, les feuilles de calcul pour l’érable et le bouleau jaune ainsi que des instructions sur comment procéder se retrouvent sur le site Web de Forintek.
Work reported in this study was carried out with the key objective of evaluating fasteners holding capacity in commercial wood panels for the purpose of exploring potential markets or expanding existing ones for OSB and other panel products in the upholstered furniture industry.
In order to have a better understanding of the upholstery furniture industry, visits were made to major upholstered furniture manufacturers in the Montreal area in November and December of 2003. These visits provided the research group with a comprehensive knowledge on the various types of wood materials and processing technologies being used at these plants, including ways of connecting the various components of the frames. Interviews with the plants staff indicated that fasteners holding capacity in OSB and other panel products are some of the major issues that are currently limiting the increased use of wood-based panels in the upholstered furniture industry.
In order to better understand the relationship between the fasteners holding capacity and the density distribution in panels, a comprehensive testing program was established. A total of 20 panels of medium density fiberboard (MDF), 16-mm thick, particleboard (PB), 16 mm thick, and oriented strand board (OSB), 11 mm, 15 mm, and 18 mm thick, with 4 replications each, were scanned using a commercial X ray system to obtain in-plane (horizontal) density distribution of the full size panels. In addition, basic panel properties (i.e., bending strength (MOR) and stiffness (MOE), internal bond (IB) and density profile) were determined. Sampling of test specimens from mapped panels was carried out in such away to cover low and high horizontal density zones.
Fasteners holding capacity tests including; lateral resistance of screws, edge and face withdrawal and head pull-through resistance of screws and staples were carried out. Correlations between fasteners holding capacities and localized horizontal density distributions were established in order to investigate how density distribution within the plane of the panel could affect the fasteners holding capacity. Investigations on the fasteners holding capacity in panel specimens subjected to static and cyclic loadings were made as well for the purpose of examining the effect of repeated cycles of loading and unloading events (i.e., short-term fatigue).
Findings from this study indicated that poor fasteners holding capacity especially on the edge of the panel is one of the key panel attributes that is currently limiting the use of OSB and other wood panel products in the upholstered furniture. Fastener driven in low density points or zones may fail at much lower load level than that driven in high density points with failure initiating at those low density zones and progressing to other zones from there (i.e., loaded end or edge distance). For the type of cyclic loading regimes used in this study (90 cycles at different load levels), no significant differences were observed.
Recommendations are given on how to improve the panel attributes in order to increase the fasteners holding capacity and resolve some of the technical issues limiting the market access of wood panel products in the upholstered furniture industry.
The International Woodworking Machinery and Furniture Supply Fair (IWF) was held on August 26-29 at the Georgia World Congress Center in Atlanta, Georgia (Figure 1). The IWF presented more than 1,200 exhibitors related to the secondary wood processing sector. The primary purpose of the IWF is to offer the unique opportunity of showcasing a wide variety of exhibitors all under one roof.
As a buyer, or observer, one has the unique opportunity to see thousands of square feet of the latest technology, new machinery, suppliers, raw materials and services, as well as the most current technology available to the marketplace. Most major woodworking machinery manufacturers in the world were present to talk and meet with industry leaders; see the machines in operation, and learn about all the new advancements in technology being shown for the first time. This opportunity is unmatched in our industry. The IWF venue also brings together industry trade associations and educational resources to help with the day-to-day challenges facing the industry.
Representatives of the Eastern and Western laboratories of Forintek Canada Corp. attended IWF 2004. The purpose of the mission was to view and gather technical information on the latest equipment and processes related to the secondary wood products manufacturing industry and bring the relevant information back to value added products industry of Canada. This mission was also useful to find technical information relevant to Forintek research projects supported under the National Research Program (NRP).
The mission report presents information on leading-edge technologies, new products, and knowledge and services that could be considered to increase the productivity and competitive level of secondary wood manufacturers in Canada.
This study examined the impact of initial spacing on tree characteristics, product quality and value recovery in jack pine. The study was based on one of the oldest initial spacing trials established in 1941 in Wellston, Michigan. In 2001, trees were collected from each tree DBH class in 3 initial spacings, 5x5 (1.52mx1.52m), 7x7 (2.13mx2.13m) and 9x9 (2.74mx2.74m). Trees were also collected from blocks that had been spaced (PCT) from 5x5 to 7x7 at age 13. The following were measured for each sample tree: crown width and length, total tree height, tree height up to 7.5cm top, tree height up to 9.1cm top (10cm DBH class) and average diameter of the 5 largest branches. Based on these measurements, stem volume, stem taper and length of the log below live crown were calculated. Each stem was then scanned in a log scanner for determining the impact of optimized bucking and sawing on lumber recovery using sawmilling simulation software. Stems were bucked into 8-foot long logs with a 4-inch overlength (2.54 m) according to sawmill practice. A 5-cm thick disk was collected from the base of each stem and from the top of each 8-foot sawlog for wood quality determinations. Lumber conversion was carried out in 4 separate batches so that chip samples could be collected for determining chip and pulp quality. Each piece of lumber was visually graded both before and after kiln drying. A static bending test was also performed to determine lumber strength and stiffness. Based on the sample trees, the impact of initial spacing and the PCT treatment was evaluated at the DBH class level and at the stand level. Finally, a benefit/cost analysis was made for the 4 treatments. Wood and pulp properties and sawing simulations will be reported separately.
Increasing initial spacing in jack pine from 5x5 to 7x7 had a considerable impact on average tree diameter (+14%) and volume (+30%) 57 years after planting. However, when spacing was further increased to 9x9 the additional gains in tree diameter (4%) and volume (3%) were considerably more modest. On the other hand, the PCT treatment in the 5x5 spacing in which stand density was decreased from approximately 4300 trees/ha to 2200 trees/ha, increased tree DBH by 6.6% and tree volume by 18%.
The negative impact of increasing initial spacing and PCT treatment on branch size and tree taper follows a similar trend. Average branch diameter in 5x5, 7x7 and 9x9 spacing was 30.1, 35.1 and 37.0mm respectively and 32.8mm in the thinned 5x5 stand. Average tree taper also increased considerably as spacing was increased from 5x5 (0.64cm/m) to 7x7 (0.79cm/m), the increase was much less as spacing was further increased to 9x9 (0.86cm/m).
Average nominal lumber volume recovery also increased considerably with increasing initial spacing. Once again the increase was more pronounced in narrow to moderate spacing than from moderate to wide spacing. On the other hand, lumber grade recovery did not decrease with increasing initial spacing in this study, as suggested by the increase in branch and knot size. In fact the highest yield of SS grade was in lumber from the 9x9 spacing, and its yield of SS & No. 1 lumber, is only marginally lower than that of lumber from the narrow 5x5 spacing. This is largely due to the fact that rot was also a major cause of downgrade in all stand densities and its impact was somewhat less important in the widest spacing. The presence of rot alone was responsible for 24.7% (9x9) to 56.9% (5x5) of lumber downgrade to No. 3 and Economy, which has a direct and significant impact on lumber value.
Lumber strength and stiffness decreased with increasing initial spacing. The modulus of elasticity (MOE) and modulus of rupture (MOR) of lumber from the widest spacing are 7.4% lower than those of lumber from the narrowest 5x5 spacing. But, the MOR of lumber from moderate (7x7) spacing is only approximately 3% higher than that of lumber from wide spacing (9x9). MOE and MOR of lumber from the thinned and unthinned 5x5 spacing are very similar which indicates that the PCT treatment did not seriously affect bending properties. In addition, the mechanical properties of those 2 stands compare well with those of lumber from young 50-year old natural stand. Generally, MOE and MOR decreased from butt log to top log in all spacings.
An economic analysis was carried out for a 47 and 57-year rotation using tree and lumber data that were generated for each tree DBH class in the 2001 study, as the initial spacing trial was 60-years old. The economic analysis was carried out in the context of sustainable forestry through intensive silviculture, which assumes that trees are planted each year at the same initial spacing. And for each year of operation, return on investment or benefit to cost ratio is estimated using current product values and costs.
The analyses indicate that benefit to cost ratios increase with increasing initial spacing both at 47 and 57-year rotations. However, none of the stand densities generated any profit at 47-year rotation mainly due to high harvesting and processing costs. It is nevertheless estimated that the widest initial spacing (9x9) would have shown a positive economic return on investment (B/C 0.96 in this analysis) had lumber values been based on 47-year old stems rather than 60-year old stems, since lumber downgrade due to rot would have been lower. In addition, improvements in lumber processing would also have a positive impact on stand value and profit. But, in order to be profitable on short rotations, plantations should be established in regions that are particularly favourable to jack pine growth.
In the 57-year rotation only the narrow 5x5spacing failed to generate profit (Benefit/cost 0.87). The economic impact of a precommercial thinning treatment in the dense 5x5 stand appears to be modest. However, in plantation-grown jack pine and especially in stands such as the one in the present study where tree form is a major problem, PCT treatments should be primarily aimed at eliminating deformed stems to have maximum impact on tree and stand value.
It appears that this stand should have been harvested before age 60 since there was high mortality in the last 10 years and essentially no additional volume growth. In fact, the only positive growth that was recorded from age 47 to 57, was in the 9x9 spacing with 8.6m3/ha over the 10-year period.
This study examined the impact of precommercial thinning (PCT) intensity on tree characteristics, product quality and value recovery in jack pine. The study was based on one of the oldest precommercial thinning trials established in 1966 on a poorly drained sandy-silty loam by the New Brunswick Department of Natural Resources and Energy. The trees on this site originated from fire in 1941. In 2000, 6 trees were collected from each commercial tree DBH class in 3 thinning intensities, 4x4 (1.22mx1.22m), 5x5 (1.52mx1.52m), 7x7 (2.13mx2.13m) and a control stand, for a total of 154 trees.
The following were measured for each sample tree: crown width and length, total tree height, tree height up to a 7-cm top, tree height up to 9.1-cm top (10-cm DBH class) and average diameter of the 5 largest branches. Based on these measurements, stem volume, stem taper and length of the log below live crown were calculated. Before bucking, the shape and size of each stem was determined using a laser transit and a target board overlaid with high precision graph paper. These virtual stems will be used to determine the impact of optimized processing on product volume and value recovery using a sawmilling simulation software developed by Forintek (Optitek).
Stems were bucked into 8-foot long logs according to sawmill practice. A 5-cm thick disk was collected from the base of each stem and from the top of each 8-foot sawlog for wood quality determinations. Lumber conversion was carried out in 4 separate batches so that chip samples could be collected for determining chip and pulp quality. Each piece of lumber was visually graded both before and after kiln drying. A static bending test was also performed to determine lumber strength and stiffness. Based on the sample trees, the impact of PCT intensity was evaluated at the DBH class level and at the stand level. Finally, a benefit/cost analysis was made for the 4 treatments. Wood and pulp properties and sawing simulations will be reported separately.
Since jack pine is a shade-intolerant species mortality decreased with increasing PCT intensity, as expected. Mortality in the 7x7, 5x5 and 4x4 thinning was 16.7, 20.6 and 24.2% respectively, and 29.6% in the control stand.
The impact of mild (thinned to 4x4) and moderate (thinned to 5x5) PCT treatment on tree growth was relatively modest 34 years after treatment. However, when thinning intensity is further increased to 7x7 (2200 stems/ha) the gains are considerable. Tree diameter increases by over 20%, from 15.1cm in the control stand to 18.3cm in the stand thinned to 7x7. Average tree height increases from 14.5m to 16.4m (13.1%) and merchantable stem volume per tree increases by more than 75%, from 105.1dm3 to 185.5dm3.
Total log volume recovery and green lumber volume recovery per tree is respectively 67% and 59% higher in trees from intensive thinning than in trees from the control stand. Lumber volume recovery per cubic meter of stem is slightly higher in trees from the 7x7 thinning than in trees from the control stand, and as a result wood consumption in the intensive thinning is somewhat lower. On the other hand, trees from the 5x5 thinning and control stand generally have similar log and lumber volume recoveries, which are higher than those from the 4x4 thinning.
Lumber quality generally increases with increasing thinning intensity. Yields of visually graded No. 2 and better lumber are 87.7%, 86.0% and 77.5% in stands thinned to 7x7, 5x5 and 4x4 respectively, and 79.2% in lumber from the control stand. The presence of large knots is the main downgrading defect in jack pine lumber from intensively thinned stands where it is responsible for 27.4% of the downgrade, while wane is responsible for approximately 25 to 30% of the downgrade in lumber from the control and mild thinning stand. Lumber and total product value recoveries per tree are approximately 70% higher in trees from intensive thinning than in control trees. And lumber value per thousand feet board, and per cubic meter of stem, are 14% higher in trees from intensive thinning. Once again trees from control and moderate thinning (5x5) have similar product value recoveries and these are superior to those of trees from mild thinning.
The economic analysis indicates that return on investment increases with increasing thinning intensity. Benefit to cost ratios, are 1.26, 1.31 and 1.46 for stands thinned to 4x4, 5x5 and 7x7 respectively. However, the unthinned control stand has a higher benefit to cost ratio (1.33) than stands from mild and moderate thinning. It thus appears that stand density has to be reduced to approximately 2200 stems/hectare (7x7) to be economically viable.
On the other hand, strength and stiffness properties of lumber decrease with increasing thinning intensity. The modulus of rupture (MOR) in stands thinned to 4x4, 5x5 and 7x7 is respectively, 57.2, 55.3 and 46.9 MPa, and the modulus of elasticity (MOE) is 11 242, 10 927 and 9823 MPa. MOR and MOE in lumber from the control stand are 51.9 MPa and 10 219 MPa, which is respectively 10.6% and 4.0% higher than those of lumber from intensive thinning. While bending properties of lumber from intensive thinning are the lowest in this study, they are nevertheless comparable to those of lumber from natural stands of good to excellent growth, as demonstrated in a recent study in 50, 73 and 90-year old jack pine stands from Northern Ontario. Lumber strength and stiffness also decrease fairly drastically from the butt log to the top log in all stands.
In summary, the results from this study indicate that mild and moderate thinning treatments do not have sufficient impact on tree and stand volume and value recoveries to generate a positive return on investment. A fairly intensive PCT treatment is thus required to be economically viable. It also appears that strength and stiffness properties of lumber from intensively thinned stands will be similar to those of lumber from natural stands of similar rotation age.
The impact of commercial thinning of jack pine stands on growth, yield and financial variables was examined. Data from 5 treated stands spread through Eastern Canada was used to calibrate individual tree and stand level models. Individual trees showed a good response to thinning, with the larger stems having the best reaction to thinning. Larger stems, however, could not take full advantage of the heavy thinning. At stand level, thinning had little effect on merchantable volume. Sawlog volume (merchantable volume of the stems with a diameter at breast height of 15.1 cm and more) showed a strong response to thinning, with heavy thinning having more sawlog volume. Thinning reduces the income of a stand, but reduces even more the cost to harvest and saw the stand. The return on investment and net present value (NPV) favour heavily thinned stands, with moderately thinned stands having the same NPV, but higher return on investment.
Impact of rotation age
This study examined the impact of rotation age on tree and wood characteristics, lumber quality and value recovery in natural jack pine forests. The study was based on three stands all established after forest fires in the region of Timmins, Ontario. These stands were 50, 73 and 90 years old. In 2002, a total of 142 sample trees were collected. For each stand, 6 trees per DBH class were selected to cover all diameter classes (DBH) in 2-cm interval. For each sample tree, major tree characteristics were measured: total tree height, tree height up to 9.1 cm diameter top (10 cm DBH class); DBH and stem diameter from the stump to the top at 1-m interval; live crown width and length and average diameter of the 5 largest branches. Based on these measurements, other tree characteristics were calculated: stem volume, stem taper, and length of the log without live crown. Each sample tree was bucked to 8-foot-long logs for lumber conversion. From the top of each log, a 3-cm-thick disc was removed for the evaluation of wood characteristics. Lumber conversion was carried out in a way which allows to keep track of the provenance of each piece of lumber. Logs from each stand were processed separately so that chip samples could be collected. Each piece of lumber was visually graded after drying and planing. Bending tests were performed to determine the mechanical properties (bending strength and stiffness) of the lumber pieces. Based on the sample trees, the impact of rotation age was evaluated first at the diameter class level and then at the stand level. Finally, a cost/benefit analysis was made for the three rotation ages.
For the three stands analyzed, tree height, tree diameter, tree volume, branch diameter and taper increased with diameter class (which is an effect of age). Basic density (90 yr-old stand data only) decreased from butt log to top log for all diameter classes.
Since the quality of the natural jack pine stands was excellent, the Economy grade accounted only for 2.4% or less of the total lumber volume production for each stand in this study. In the 90-yr-old stand, decay caused 20.6% of the downgrades, whereas for the 73- and 50-yr-old stands, downgrades due to decay was low or inexistent (5.2% and 0% respectively). When grades No. 2 and better were combined (current market practice), no significant differences were found among the three rotation ages.
The present study clearly shows that rotation age influences lumber quality. The 50-yr-old stand had a significantly lower lumber strength (MOR, 42 MPa) about 16% below that of the 73- and 90-yr-old stands (48 and 49 MPa). This can be partly explained by a higher proportion of juvenile (immature) wood at an age of 50 years. The lumber stiffness (MOE) at age 50 was also significantly lower (19 and 16%, 9441 MPa) compared to the 73- and 90-yr-old stands (11234 and 10927 MPa respectively). From the lumber strength and stiffness point of view, the 50-yr-old stand can be considered too young for harvest. The two older stands were similar in terms of lumber mechanical properties, which were very good (i.e. met or exceeded the mean-based MOE design values of the grade, unlike the 50-yr-old stand). For the three rotation ages, MOR and MOE decreases from the butt log to top log.
The benefits/cost analysis indicates that it is economically more profitable to harvest natural jack pine stands at an age of 90 years. However, regarding stand productivity, the 90-yr-old stand showed the lowest annual stand volume increment of 3.21 m3/ha/year, compared to 5.25 and 3.82 for the 50- and 73-yr-old stands, respectively. The stand also showed the highest mortality (loss of fibres) and rate of lumber downgrades due to decay. From the view point of lumber properties, downgrades due to decay and tree mortality, a moderate rotation age of about 70 years is preferred in jack pine.
L’utilisation massive d’oxyde d’aluminium dans l’industrie des lames de plancher prévernis cause toute sorte de perceptions. Parmi celles-ci, on associe les problèmes de fendillement de surface des lames de plancher à des taux élevés d’oxyde d’aluminium. Un système de finition se bâti de plusieurs couche de polymère et ce n’est généralement que la dernière couche qui comporte la charge inerte. Il est aussi une autre école de penser qui indique que les pratiques de séchage font en sorte que les lames sont vernies à des teneures en humidité inadéquates. En bref, peu de connaissances sur les pratiques de prévernissage sont disponibles.
L’objectif de cette étude visait à identifier la ou les sources à l’origine du fendillement dans les lames de plancher de bois franc. Par la même occasion, nous avons tenté de confirmer ou d’infirmer les perceptions populaires quant à l’influence de la teneur en oxyde d’aluminium et de la teneur en humidité du bois lors du vernissage sur le bon comportement du vernis. De plus, l’ensemble de cette démarche offre l’occasion de documenter et de mettre à l’épreuve certaines normes et essais liés au vernis.
Les résultats n’ont pas démontré d’effets significatifs du taux d’oxyde d’aluminium ou de la teneur en humidité des lames de plancher sur la résistance à l’impact et sur l’adhérence du vernis. Ce n’est toutefois pas le cas pour l’épaisseur du film, la résistance à l’abrasion, la dureté Pendulum du vernis, la brillance du vernis. Toutes ces propriétés sont influencées par ces paramètres.
Au niveau des fentes, les observations mettent en évidence les aspects anatomiques du chêne. En effet, le chêne comporte d’importants rayons ligneux qui se présentent comme une zone de faiblesse dans le plan longitudinal tangentiel. C’est encore plus vrai si les pratiques de séchage ont été sévères. Dans plus de la moitié des fentes observées, du vernis était présent, ce qui confirme que celles-ci étaient présentes lors du vernissage. Ce problème se produit aussi dans d’autres espèces difficiles à sécher telle que le Jatoba.
In the most recent edition of the CSA O80 wood preservation standards (1997), retention by assay rather than by gauge was specified for chromated copper arsenate (CCA), ammoniacal copper arsenate (ACA), and creosote. Based, in part, on data from Forintek’s field trials, these assay retentions are lower than the old gauge retentions, and lower than the assay retentions which had been specified in the standards of the American Wood-Preservers’ Association (AWPA). The AWPA independently introduced lower retentions for northerly waters in 1995. Continued testing was needed to confirm that the lower retentions would still provide the service life required from marine structures.
The marine tests covered in this report were set up in 1978 in West Vancouver, BC, and in 1984 at two sites in New Brunswick. Red pine sapwood coupons were pressure-treated with a range of retentions of preservatives that were listed in the standards at the time. They were suspended in the water column on metal racks and inspected once a year until 2000 at West Vancouver and 1997 at the New Brunswick sites. They were given a final inspection in 2004.
At the West Vancouver test site, coupons treated to the recommended assay retention with CCA-C (24 kg/m3) were in good condition after 26 years’ exposure. ACA-treated coupons at the recommended assay retention of 30 kg/m3 had failed as a result of surface degradation by bacteria and fungi. While significant on a thin test coupon, such degradation on a marine pile or timber would have less effect on the strength of the structure. Wrapping the ACA-treated coupons for a period after treatment to simulate the drying rate of large-dimension commodities did not improve performance, nor did using an alternative formulation with a higher proportion of copper. The performance of creosote at above-the-recommended retention was superior to ACA, but significantly inferior to CCA.
Untreated coupons failed in less than a year at West Vancouver and between 2 and 3 years at the New Brunswick sites, Shediac Bridge and Whitehead Island. At Whitehead Island, coupons treated to the recommended assay retentions with CCA and ACA were still performing well after 20 and 17 years’ exposure, respectively (higher retentions of ACA were added 3 years after the experiment was set up). However, at Shediac, while CCA-treated samples treated to 24 kg/m3 remained sound, coupons treated to 30 kg/m3 ACA had deteriorated badly after 10 years in test. In contrast, samples treated to close to the recommended retention with creosote performed better at Shediac Bridge than at Whitehead Island.
Interestingly, the pressure-treated wood has performed better than the test racks. The racks at West Vancouver, made from 3.5 mm thick carbon steel, had moderate corrosion after 10 years and had to be replaced after only 15 years of service.
This year-end report for the continuing project “Decision Aids for Durable Wood Construction” focuses on international activity in building envelope research. One of the major task areas within Decision Aids is knowledge maintenance about related work elsewhere; 2004/2005 was a particularly active year for building science conferences, which are the primary venue for research reporting in this field. Short summaries of current work are provided, organized by institution. In addition, the other activities under Decision Aids are also reported, including an expansion of the durability web site and an update on the proposal for an outdoor test facility in Vancouver.
Commercialisation of a low maintenance transparent coating is expected to assist wood products maintain residential market share in the face of competing materials and potentially expand markets in recreational property and non-residential applications. Testing of a range of commercial products had identified one outstanding performer and arrangements were made to work with the developer of this coating to further improve its performance, targeting a 15 year life under Canadian conditions. Exposure tests were set up to evaluate potential improvements in resistance to UV and to black stain fungi. Unusually favourable conditions for black stain fungi in the first six months of exposure provided some early results. Neither of the two reference coatings were as resistant to black stain as the experimental formulations. Furthermore, simply changing from the earlier manufacturers recommendation of one coat of step one and one coat of step two to two coats of step one and one of step two showed improvement in resistance to black stain. One of the modifications to the UV protectant system had a negative effect on resistance to black stain. None of the fungicides tested were more effective in protecting against black stain than IPBC, the fungicide in the commercial formulation. Furthermore a new formula of IPBC was not as effective as the older formula. However, two patterns of black stain were noted and there appeared to be some variation among fungicides in their resistance to these two patterns. A combination of IPBC and Propiconazole may be effective in protecting coatings from a broader range of black stain fungi. Further exposure is required to quantify any benefits to the UV protectant system or from pre-treatment with the hindered amine light stabiliser, Lignostab, with and without oxine copper.
Bluestain fungi reduce the market value of Canadian wood products causing significant economic losses and are considered by many countries as potential alien pests. One of the key knowledge gaps in bluestain biology is the source of the stain and how the bluestain fungi spread. This report is a compilation of reports that are included in the appendices (1-14), each with its own targeted objectives, methodologies, staff, and results and discussions. The acquired knowledge will help us design economical, effective and environmentally acceptable methods to control bluestain at different stages of the wood processing chain. In order to fill the knowledge gaps and identify new ones, we set up a worldwide collaboration where partners contributed much of the expertise, especially on fungal and insect identification. Forintek staff organise the industrial interface, do field work, isolate and identify fungi (in collaboration with partners), provide summary reports (updates) to members, and continue to maintain core competency in this field.
Stain inoculum is found associated with wood substrates, needles, cones and bark of trees (Appendix 4). Harvester heads presumably pick up stain inoculum while touching wood, soil and woody debris. During harvesting they push the inoculum together with pieces of bark and other debris deeper in sapwood, clearly playing a role in direct dissemination. Harvesters also puncture the wood and loosen and remove bark, which provides access to sound wood for a plethora of organisms. If mechanically harvested logs are left unattended for several weeks under warm and humid conditions they can develop bluestain solely based on the stain inoculated during harvesting. Stain control methods therefore need to be applied immediately. This can include hot logging (log delivery and processing within 2-4 weeks), water storage, debarking, drying and antisapstain treatments (including biocontrol).
Numerous insects visit standing trees and logs in storage. Insects are known to be one of the major vectors for bluestain fungi. Despite a great deal of research on insect-fungi relationships, there remain many unanswered questions. These include the specificity and the importance of these associations for both partners, and pathogenic potential and staining ability of associated fungi. Very few beetles can attack healthy standing trees, like the Mountain pine beetle, which causes bluestain that cannot be prevented unless the beetle is controlled. Some insects, especially bark and ambrosia beetles, may attack only one type of host and carry only one or two specific fungi. Others can attack many hosts and can carry a variety of fungi. Some of these associations are very specific and the survival of an insect depends on the fungus. In other systems the fungus may be a weed picked up casually. We created an insect-fungi database to conveniently capture and update information on known insect-fungi associations currently focusing on bark and ambrosia beetles. Often the primary beetles carry more pathogenic symbionts and are more extensively studied than in secondary, later-arriving, beetles where little information exists on their fungal associates. New associations are regularly being discovered. Novel approaches in stain and disease control aim to trap insects that carry fungi of significance using semiochemicals (“message-bearing” biochemicals). The database will be used as an aid to manage and access the critical information that might lead to novel methods of control. To date, 200 articles have been entered (Appendices 1, 2, 3, 5, 6, 10, 11, and 12).
The insect-fungus database is complementary to the Ophiostomatoid fungi database that has been developed at UBC through partnerships with Forintek and scientists around the world. The first phase is realized and this online database now contains all the available information on the most economically important species of sapstain fungi. It includes fungi-host-vector-geographical location relationships; both published historical information and new information acquired through fieldwork. With the help of our partners it will be continuously improved and updated during its lifetime (Appendices 7, 8, and 9).
We also studied other potential stain sources. In early February 2004 the Forintek team went to two BC mills that process bluestained, mountain-pine-beetle-attacked logs and sampled air and airborne sawdust at six locations in the mills, as well as from sawmill machines and surrounding snow. Stain fungi were rarely found in the air, accounting for up to 0.4 % of the total amount of fungal propagules in the dustiest areas of the mills. Live stain fungi were found in the snow (1-2 % of total cultured organisms), but the largest counts of stain fungi were found near machines with the dust settling method, and directly on the mill machines (up to 20.5% of total cultured organisms). This suggests that machinery may play the most significant role in stain inoculation to clean wood, while large sawdust pieces may play a significant role only for short distances (Appendix 13).
With increased emphasis in the Canadian forest products industry on extracting the most value from logs, this work will continue under ongoing project Biology and Management of Bluestain Fungi. It will continue to address the problem in order to recognise situations and ways where stain may be prevented along the wood processing chain (Appendix 14).
Western redcedar (WRC) is renowned for its high durability, which is due at least in part to the presence of extractives that are toxic to decay fungi. Western redcedar's naturally low equilibrium moisture content (EMC) may also be a protective factor, since fungi typically require 30% moisture content to grow. Extractives are thought to contribute to the low EMC by blocking water adsorption sites on the wood. The present work compared the EMC of extracted and un-extracted WRC heartwood and sapwood. Extracted WRC heartwood had higher EMC than un-extracted WRC heartwood in samples not affected by fungi, and WRC sapwood had higher EMC than adjacent heartwood. The presence of extractives was identified as being associated with the low EMC of WRC heartwood in these samples.
This report sketches design and construction issues of relevance to wood over the past year, as seen from within the construction sector itself. Information was assembled from a variety of sources geared for architects, engineers, builders and other members of the construction community.
Mold can sometimes grow on building materials that are wet or held in a humid atmosphere. Wetting can be by liquid water or water vapour or both. Of the wood-based building products, oriented strandboard (OSB) is perceived by some specifiers as being one of the most susceptible to mold growth. A potential tool to control mold growth in the event that oriented strandboard gets wet in transit, in storage, or at a sales or use location, is chemical treatment. The objective of this study was to obtain information on what surface treatments prevent mold growth when dry OSB is wetted by water vapour under conditions of high humidity.
In recent years, significant attention has been paid to the engineering performance of wood structural systems, and a new generation of more reliable engineered wood components for building construction has evolved.
The latest trend is towards advanced products that combine wood and synthetics. This increases performance and structural reliability of engineered wood products, and leads to new markets and expanded opportunities. It is anticipated that cost of fibre reinforcement decreases over time and advances developed on reinforcing techniques and methods of evaluation would provide wood producers with more options to better position their products in the marketplace.
A new reinforcing technique has been developed and applied to manufacture a hybrid wood product for structural applications. The technique involves a layering analogy using layers of synthetic reinforcement sandwiched between layers of wood composite. The products manufactured in the laboratory used regular OSB laminations and alternating layers of E-glass fabrics and resin. Three- and four-ply billets were manufactured with various layouts and then tests were conducted to characterize mechanical properties of the hybrid products. Overall, the test specimens performed well relative to the controls. Shear failures were observed as a result of the limited performance of OSB in shear, and consequently the next tests will be conducted with plywood laminations instead of OSB.
Selected issues related to code acceptance of structural FRP-reinforced wood products are discussed in the appendix. Future work is suggested to completely characterize and understand the properties and behaviour of the FRP-reinforced wood products, including fire performance, long term durability, maintenance and cost, in order to establish an environment in which to work comfortably with such materials. Overcoming these issues is vital for product acceptance in building codes.
The high natural durability of western redcedar (WRC) heartwood is primarily attributed to the presence of extractives that are toxic to fungi. However, its durability may also come from its low equilibrium moisture content (EMC). Recently extractives were found to contribute to western redcedar heartwood's low EMC (Stirling and Morris, 2005). In the present study we sought to determine the degree to which certain groups of extractives contributed to this low EMC. The non-polar tropolones were found to have no effect on WRC's EMC. Lignans, where are abundant in WRC heartwood, were associated with its low EMC. In addition to the known extractives there are likely other differences in chemistry or structure that account for the low EMC of WRC.
Ultraviolet and visual light can damage wood; so many finishes include chemicals for UV protection. The efficacy of these chemicals depends on a wide variety of factors, but at a fundamental level it is related to their ability to absorb or reflect strongly over a wide range of frequencies. This report describes the use of UV/Visible spectrophotometry to measure the transmittance of light radiation through finishes. The development method was applied to measuring the effects of additives and to comparing commercial finishes.
The performance of decking with relatively shallow preservative penetration is currently of interest to standards committees. A variety of non-incised nominal 2 x 4 inch decking was put into test by Forintek's Vancouver laboratory between 1981 and 1985. Two sets of non-incised CCA-treated hem-fir with preservative penetrations close to the 1997 CSA O80 decking standard have remained in very good condition after 21 and 24 years' exposure. These results confirm that the reduced penetration requirement introduced in 1997 provides effective protection from decay in above-ground applications. Decking double-vacuum treated with 0.5% PCP performed better than material dip-treated with 5% PCP when evaluated after 24 years in test. Following 20 years' exposure, decking treated with Arquad B-100 at 6.4 kg/m3 by uptake has performed as well as decking CCA-treated to the new CSA O80 decking standard. Untreated western white pine has performed better then hem-fir after 23 years' exposure.
Experimental roof panels constructed using western redcedar shakes and shingles, untreated and treated with three waterborne preservatives, have been in test for 25 years at two locations in the lower mainland of British Columbia. Moderate physical deterioration in the form of erosion and splitting was present in both treated and untreated samples, but virtually all treated samples were free from decay. Minor amounts of decay were detected on some of the untreated shakes, and to a greater extent, the untreated shingles. Because the chemical loading of these treated samples is so much higher than what is currently recommended, the lack of decay is not surprising. A small study of the extractives content of untreated samples revealed that, after 25 years of service, the shakes retained more extractives than shingles, although both were at very low concentrations.
A field test of untreated and preservative-treated round fence posts has been running at Petawawa, Ont. since 1937. Service life data without preservative treatment on 20 eastern Canadian wood species were developed. In addition, treatments by a variety of pressure and non-pressure processes with waterborne and oilborne preservatives were tested. Thermal immersion in creosote was the most effective non-pressure method used, while brush treatments and cold soaking proved to be ineffective for long-term protection from decay. Pressure treatment using standard waterborne (CCA and ACA) and oilborne (creosote, pentachlorophenol, copper naphthenate and oxine copper) preservatives provided excellent protection. Several preservative/species combinations gave mean service lives well over 50 years.