The major defining characteristic of lumber cut from trees that have been infected with the mountain pine beetle is the extent of fungal bluestain in the sapwood. It is reported that bluestained wood has shown increased permeability, and questions arose as to whether the application of an adhesive or a finish coating may be adversely affected. Laminating of wood is a key value-added process and one that is very dependent on the quality of the bond between two or more components. Bluestain is a common phenomenon in the secondary wood processing industry where finishing is part of the value-adding process. The finishing evaluations made in this study were intended to benefit these processors.
Pieces of bluestained and non-stained 2 x 4 in. lodgepole pine lumber were dried to a moisture content typically targeted by the furniture sector — i.e., much drier than lumber used for structural purposes. From this lumber, specially constructed edge-glued panels were made which exhibited bluestained to bluestained joints and non-stained to non-stained joints. This construction method provides bluestained and non-stained joints for the laminating tests, as well as providing a good representation of what will really happen in an industrial setting where bluestain most likely will not be separated from non-stain. Each panel was cut in half, with one half being used for the laminating tests and the other half for the finishing evaluations. The strength and durability of the glue lines were measured. Various finish coatings either used alone or in combinations with others were subjectively evaluated.
The laminating tests show that gluelines in lodgepole pine that contains beetle-transmitted bluestain were not significantly different in strength from gluelines in unstained wood when PVA and PRF adhesives are used. The durability of the bluestained beetle-killed wood gluelines easily met the requirements specified by the ASTM D1101 standard.
Where desired, the appearance of bluestained wood can be enhanced or highlighted by a simple standard clear furniture finish. Bluestain in parts of edge-glued panels can be masked if certain types of finishes are employed. The finishes that gave more consistently good masking results were those containing blue, red, and charcoal tints in the stain, toner, or glaze coatings. Increased permeability of the bluestain did not affect the adherence of any of the finishes.
While the finishing evaluations indicate the possibilities for finishing pine, whether it has bluestain or not, market research is recommended, using the best performing finishes on full-scale furniture pieces, to test consumer acceptance.
The extensive outbreak of mountain pine beetle in north central British Columbia is resulting in a large volume of lodgepole pine coming into the log supply for sawmills. The major defining characteristic of beetle-infested trees is the bluestained sapwood caused by fungi carried by the beetle. Because bluestained wood is not very familiar to some consumers, this wood may pose a marketing challenge. Although the non-appearance properties of bluestained wood are widely recognised by the industry as not being compromised, there are no data to support this belief. The literature on other types of bluestained wood reports up to 30% lower impact bending strength (toughness) and higher permeability than for non-bluestained wood.
Forintek Canada Corp. scientists identified the need to generate data on some properties of beetle-killed wood in order to address potential concerns. Approximately 270 pieces each of bluestained lodgepole pine lumber cut from beetle-attacked trees, and equivalent non-bluestained lumber were collected from 14 different sawmills in the B.C. Interior. This was delivered to the Forintek Vancouver laboratory for conditioning and processing into test specimens. The specimens were allocated, in equal proportion from each mill, between tests of mechanical, dimensional stability/permeability, gluing, and finishing properties. The results are presented here and in three associated reports.
This is the first compilation of work on the properties of beetle-transmitted bluestained wood. Overall, the research indicates that this wood can be used, without compromising performance, for structural, furniture, and preservative-treated end uses.
A factsheet summarizing the findings produced for customers of bluestained wood is included in the appendix to this report.
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.
Exposée à la chaleur élevée, la structure chimique du bois se modifie. Des recherches sont en cours depuis plusieurs années quant à l’impact de ces changements sur les propriétés physiques et mécaniques du bois. Différentes technologies de modification thermique ont été développées et plusieurs brevets ont été octroyés à ce sujet. Le bois thermiquement modifié commence à prendre sa place sur les marchés européens, et ce qui suit vise à répondre aux questions les plus fréquentes concernant la technologie et le produit résultant de la modification thermique du bois.
When wood is exposed to high temperature, its chemical structure is modified. For a number of years, research has been conducted on the effects of such modifications on the physical and mechanical properties of wood products. Several thermal modification techniques have been developed, and a number of related patents have been issued. Thermally modified wood is becoming a factor on European markets, and the purpose of this Technote is to answer the most frequently asked questions regarding this technology and resulting products.
The process of fingerjointing is complex and requires numerous efforts in order to evaluate the various workable and optimum conditions of jointed wood members. Many factors are known to affect the strength of fingerjoints. Some are related to wood, such as species, density, natural defects, moisture content (MC), temperature, and gluability of the species. Others are related to wood machining, including type of adhesive and gluing processes, such as condition of the cutting tools, curing time and applied assembling pressure.
This guide proposes a method to evaluate the performance of optimized log and cant breakdown equipment as a tool for mill personnel to improve production efficiency. Optimized systems are found in all aspects of modern sawmills, and evaluating their ability to maximize product value is not necessarily a simple task..
Analytical methods presented in this guide are primarily intended for sawmill technical staff, i.e. technicians and engineers responsible for process improvement. With this guide and a better understanding of optimizers’ operating mode, they will be in position to implement a control method based on the efficiency of the log breakdown equipment
To be successful, a performance evaluation test needs to be properly planned. Once objectives have been clearly defined, a methodology must be laid out for the results to be significant and conclusive. Forintek specialists are available at all times to help a company set up a project of this nature.
A 2-D heat and mass transfer finite element model based on the water potential concept was previously developed to simulate the evolution of moisture content and temperature in the cross section of a piece of lumber during drying. In order to be able to use the model with an industrial interest, an user interface was developed and the experimental parameters required for the model were determined for three Eastern softwood commercial species within the project no. 2674 Drytek Enhancement for Commercial Species. The user interface was developed using the MatLab development environment. It generates the mean drying and wood temperature curves, computes the maximum effective moisture content gradient and shows the evolution of the 2-D moisture content and temperature profiles during drying. The pressure membrane technique and equilibration over saturated salt solutions were used to determine the moisture content–water potential relationship at 30, 60 and 90oC for balsam fir sapwood and heartwood, black spruce heartwood and jack pine heartwood, in desorption from green to dry conditions. The instantaneous profile method was used to determine the effective water conductivity of the same species from 30 to 90oC in the three main directions: radial, tangential and longitudinal. Experimental determination of the parameters was initiated for white spruce sapwood and heartwood and will be available in a near future. Kiln drying tests of black spruce and balsam fir were performed in order to validate simulation results.
Post and beam are still the most popular construction style in Japan. Many of the beams are laminated beams using different grade in symmetric or asymmetric designs. The main objective of this study was to use low value wood product to make symmetric beams. The designs used were define in order to limit the transformation step. In the Japanese post and beam construction, a beam such as studied in this study shows a limited interest especially when compare to solid wood beams such as Helm Fir. The idea of using low-grade hardwood in the flange of a softwood beam may be promising for special application.
Pour les usines d’OSB, un mauvais suivi de la teneur en humidité des billes de bois durant l’entreposage engendre des difficultés techniques et les pertes financières énormes. Afin d’améliorer la productivité et la qualité des produits, ces usines doivent adopter un programme de gestion des inventaires de bois vert qui intègre le suivi de la teneur en humidité des billes durant les phases précédant la transformation. Pour ce faire, l’ingénieur a besoin de modèles pour prédire l’évolution de la teneur en humidité des billes de bois durant l’entreposage afin de prévoir l’influence de ses décisions sur la rentabilité de l’usine. Des travaux de ce genre existent dans la littérature, mais sont largement basés sur les connaissances empiriques. Ce projet a pour objectifs: 1) de développer un modèle de simulation du taux de séchage des billes de bois durant l’entreposage, applicable à toutes les espèces et sous toutes les conditions; 2) d’intégrer le modèle a un vaste programme de gestion des inventaires.
Le développement du modèle de simulation de l’évolution de la teneur en humidité des billes de bois lors de l’entreposage est complété. Le modèle, dénommé DRYLOG, est basé sur le concept du potentiel hydrique. Les équations différentielles partielles de transfert de masse et de chaleur sont résolues par la méthode des éléments finis. Le modèle peut être en principe utilisé pour toutes les espèces de bois et sous toutes les conditions, car il prend en considération tous les paramètres internes et externes qui influencent le taux de séchage des billes. Les paramètres spécifiques nécessaires sont: l’espèce, la teneur en humidité initiale, la température initiale, la densité basale, le coefficient de retrait total, la relation teneur en humidité – potentiel hydrique et la conductivité hydrique effective. Les paramètres externes sont: le type d’empilement, l’orientation des billes, la hauteur de la pile, la longueur de la pile, la longueur des billes, les classes de diamètre et leurs proportions, la température de l’air, l’humidité relative de l’air, la vitesse et la direction du vent. Pour faciliter l’entrée des données, une interface graphique a été développée.
Les paramètres expérimentaux ont été déterminés pour le bois de peuplier et de bouleau. Ces paramètres ont ensuite été utilisés pour simuler l’évolution du taux de séchage des billes de peuplier et de bouleau, dans le cas de l’usine Panneaux Tembec OSB, division de St-Georges de Champlain. Les courbes de séchage générées par le modèle sont validées en utilisant les données récoltées sur le terrain. Les résultats montrent que le modèle fonctionne très bien. Cependant, des essais complémentaires sont nécessaires afin d’améliorer ses performances. En effet, des essais doivent être réalisés afin d’établir la vitesse de circulation du vent à l’intérieur de la pile en fonction du type d’empilement, de l’orientation et de la distribution diamétrale des billes. Des essais expérimentaux sur des billes, couplés aux simulations ont montré que l’écorce a une grande influence sur le taux de séchage des billes. Des études expérimentales à grande échelle seront nécessaires afin de savoir si oui ou non les pertes d’écorce sont un paramètre à prendre en compte dans le modèle.
Deux articles scientifiques ont été rédigés dans le cadre de ce projet et sont en révision. Le premier a pour titre: «Application of a mathematical model to the simulation of the impact of bark loss on the logs drying rates». Le deuxième a pour titre: «A logs drying model and it application to the analysis of the influence of length and diameter on the logs drying rates». Ils seront soumis pour publication dans les revues scientifiques aussitôt que possible.
La phase 2 du projet, à savoir l’intégration du modèle de séchage des billes dans un programme de gestion des inventaires de bois vert, n’est pas encore complétée. Plusieurs compagnies qui développent des programmes de gestion des inventaires de bois ont été contactées à cet effet. Deux de ces compagnies ont favorablement accueilli le projet. Les discussions sont en cours afin de définir les modalités d’une entente qui sera profitable aux membres. Pour cette raison, le logiciel n’est pas encore disponible pour les membres.
The major defining characteristic of lumber cut from trees that have been infected with the mountain pine beetle is the extent of fungal bluestain in the sapwood. To determine whether this bluestained lumber differs in its strength properties from non-stained lumber, small clear wood tests and a test on a truss connector were conducted.
Fourteen mills were approached and asked to provide an equal number of samples of bluestained and non-stained 2 x 4 in. lumber. Approximately 270 pieces each of bluestained and non-stained samples were collected and delivered to the Forintek Vancouver laboratory for conditioning and processing into test specimens. Small clear bending and toughness test specimens, meeting the general requirements of the standard test method ASTM D143, were prepared from an equal number of bluestained and non-stained lumber pieces. A subset of the bluestained and non-stained lumber sample was also selected and used to prepare metal plate-connected tension splice specimens. The three tests and the measured mechanical properties were judged to be sensitive indicators of any possible effects of bluestain on the structural performance of full-size lumber. For bluestain, an impact on the clear wood strength or the strength of the connector could be considered a precursor to a possible reduction in the structural performance of full-size lumber. Direct tests on full-size lumber tend to be confounded by the presence of strength-reducing growth characteristics such as knots or slope of grain, and are therefore more suited for quantifying a particular effect once it has been confirmed to exist.
The following results were found:
Wood with beetle-transmitted bluestain and non-stained wood have comparable clear wood bending properties and truss plate grip capacity.
The observed lower mean toughness of bluestained wood compared to non-stained wood was found to be only marginally significant (p = 0.05). There does not appear to be any difference at toughness levels below the lower quartile of the strength distribution.
The small differences that appear to be associated with bluestain (5% decrease in mean toughness, and 5% increase in mean truss plate connector grip capacity) are more likely to be masked by differences in the mechanical properties of the heartwood and sapwood, and, in the case of full-size lumber, by the presence of strength-reducing growth characteristics such as knots and slope of grain.
Insects - Attack on trees
Stains - Fungal
Pinus contorta Dougl. var. latifolia - Mechanical properties
The major defining characteristic of lumber cut from trees that have been infected with the mountain pine beetle is the extent of fungal bluestain in the sapwood. Forintek Canada Corp. scientists have previously observed that bluestained wood appears to have different dimensional stability characteristics than non-stained wood when subjected to repeated wetting and drying. Bluestained wood has also been reported to show increased permeability, which may make treatment with liquids such as wood preservatives easier. However, no data is available on how bluestained wood resulting from the beetle attack might affect. We therefore identified the need to generate data on the dimensional stability, checking, and permeability characteristics of bluestained wood compared with non-stained wood.
To examine dimensional stability, specimens of bluestained and non-stained 2 x 4 in. lumber were subjected to wetting/drying cycles. After 5 and 10 cycles, the amount of bow, crook, cupping, twist, and checking was measured. The permeability of the wood was also determined by weighing end-matched specimens before and after a 1-, 4-, and 24-hour dip or after a pressure treatment cycle with chromated copper arsenate preservative, and then calculating the uptake and preservative retention.
The results clearly show that when repeatedly wetted and dried, such as occurs in exterior end uses, bluestained beetle-killed wood is more dimensionally stable (less cupping and twist) and checks less than non-stained sapwood, but is more permeable to water. The stresses appear to be relieved by many micro-checks rather than fewer large checks. Overall, the improved dimensional stability should result in the lumber made from stained wood remaining straighter.
Increased permeability of the bluestained wood was confirmed by data showing enhanced chromated copper arsenate (CCA) uptake and penetration. One implication of the stained sapwood treating more readily than non-stained wood is that in batches of preservative-treated wood, the stained wood is liable to be overtreated or the non-stained wood undertreated. As anticipated, bluestain in the sapwood had no effect on the penetration of preservative into the heartwood, the most refractory part of the wood. Treatment with CCA also masked the bluestain by coloring it green.
The increased permeability probably also has implications for ease of air or kiln drying and possibly reduced degrade in the kiln.
Insects - Attack on trees
Stains - Fungal
Pinus contorta Dougl. var. latifolia - Defects
Preservatives - Permeability
Preservatives - Penetration
Pinus contorta Dougl. var. latifolia - Preservation