A survey of coatings manufacturers was conducted throughout North America with a view to identifying which companies were engaged in the production of products recommended or potentially suitable for application to exterior and interior wooden substrates with particular emphasis on Engineered Wood Products for exterior exposure. Suitable companies were asked to complete a questionnaire
The constant increase in fuel prices has highlighted the importance of limiting consumption. This guide looks at various ways of controlling fuel costs and makes specific suggestions for different logging machines such as harvesters, feller-bunchers, forwarders, skidders and delimbers.
L’augmentation constante des prix de carburant a fait ressortir l’importance d’en limiter la consommation. Le présent guide traite des divers moyens de contrôler les coûts de carburant et fournit des suggestions spécifiques aux différents engins forestiers tels que les abatteuses-façonneuses, les abatteuses-groupeuses, les porteurs, les débardeurs et les ébrancheuses.
Ce rapport décrit les résultats d’études en cours ou antérieures réalisées par Forintek sur les méthodes utilisées pour l’aboutage du bois et la qualité des produits. Il donne une description détaillée des différents paramètres susceptibles d’affecter le procédé d’aboutage et la qualité du produit fini. Il contient également une masse de renseignements publiés dans le cadre d’ateliers, de conférences ou de revues techniques. Cette information a été regroupée et intégrée dans un format simplifié de façon à être utilisable dans la fabrication des bois aboutés. L’un des chapitres porte sur le processus de qualification et de contrôle de la qualité des bois de charpente aboutés et décrit les normes canadiennes de produits spéciaux applicables. On trouvera à la fin de chaque section un paragraphe traitant d’idées de recherche novatrices, de questions importantes pour l’industrie canadienne du bois abouté et de lacunes dans les connaissances.
Sour-felling, or delayed delimbing after harvesting, has long been proposed as a method to accelerate drying of the tree stem, in order to reduce handling and transportation costs and reduce energy consumption and drying degrade in kiln drying. Recently it has also shown promise as a method to reduce development of bluestain in harvested trees. In Forintek discussions with several large sawmills in Alberta, bluestain was estimated to cause losses of at least $30 million (CAN) in a summer when weather conditions resulted in heavy stain development. Previous Forintek trials were conducted in Alberta to assess stain development in sour-felled and control trees, but these studies did not examine other possible effects of sour-felling on the manufacture of wood products, such as development of checks, ease of debarking and milling, or other unforeseen factors.
Unfortunately, weather conditions during the storage period of this test were not conducive to bluestain development, and there was no observed difference in bluestain on lumber produced from sour-felled or control logs. Therefore, other than moisture content determination of lumber, further assessment of product quality was not undertaken. There was little difference in average moisture content of lumber produced from control and sour-felled logs, although sour-felled logs yielded slightly wetter lumber. An observed advantage of sour-felling was substantially less fibre loss from sour-felled logs than from control logs during debarking.
Development of a natural finish with long-term performance should assist wood products to maintain market share in residential applications in the face of substitute materials and potentially expand markets in recreational property and non-residential applications. A range of commercially available products, reputed to be among the best in their class, were exposed for two years accelerated natural weathering facing south at 45o at test sites in Vancouver, BC and Gulfport, Mississippi, the latter in collaboration with the USDA Forest Products Laboratory. A range of pre-treatments were evaluated under these finishes including sanding, “mill glaze” treatment, chromated copper arsenate treatment and several zinc-containing formulations expected to provide some protection against UV and mold/stain. The test material was inspected every six months for discolouration, mold/stain, finish water repellency, flaking, erosion and cracking and substrate condition. Two variants of a water-based film forming finish stood out among the products tested after only one-year and showed little or no deterioration (with the right surface preparation) after two years exposure in Mississippi. With regard to the pre-treatments, sanding doubled the time to refinishing for the water-based film forming finish but had no effect on a solvent-based film forming finish. “mill glaze” treatment increased the refinishing interval, but was not as effective as sanding. Chromated copper arsenate pre-treatment doubled the life of the solvent based film forming finish but did not affect the water-based film forming finish. Zinc naphthenate pre-treatments negatively affected finish performance and zinc acetate provided no improvement in performance. The Mississippi test site provided a factor of acceleration of about 1.3 for film forming natural finishes compared to the Vancouver test site. Based on this acceleration factor, the water based film-forming finish F5 over sanded wood would be anticipated to give a life of at least 4 years without refinishing in high-end applications under Canadian conditions. All the other products tested required refinishing after 1 year or less in Vancouver.
Subterranean termites have become a major factor limiting the service life of wood products in southwestern Ontario. If preservative treatment can be demonstrated to deter termite attack, the market for treated wood products can be maintained and expanded. With the assistance of the town of Kincardine, Ontario, Forintek Canada Corp. set up a termite test in 1988. The material included commercially available red pine, lodgepole pine, jack pine, hemlock, white spruce, and mixed spruce-pine-fir. The preservatives were chromated copper arsenate (CCA-C), ammoniacal copper arsenate (ACA), and ammoniacal copper quat (ACQ). Both incised and unincised lumber was included in the tests where possible. Also used was CCA-treated hem-fir plywood.
The material was most recently inspected in the late summer of 2003. Treated material was found to be generally performing well, with some pieces showing signs of superficial surface feeding, or cosmetic damage. Some samples with low assay retentions and preservative penetrations showed more than just trace nibbles, and termites appeared to have actually penetrated through the outer treated zone. Termite entry occurred in areas on the wood surface where defects may have facilitated such entry. Material that came close to meeting Canadian Standards Association O80 standards for ground contact generally suffered only minor damage.
Material end-matched to that at Kincardine was installed at the same time at Forintek’s test site at Petawawa, Ontario, where termites are not present, with the aim of comparing rates of decay at the two sites. After 15 years of exposure, the wood samples at Kincardine show more pronounced decay than those at Petawawa, but the most significant damage is from termite attack. Termites are a much more serious threat than decay to treated wood with shallow preservative penetration.
In 1996, Forintek Canada Corp. set up a test of borate-treated lumber above ground, protected from rain but exposed to termites, in Kincardine, Ontario. The relative humidity ranged from 75 to 100% and the temperature ranged from -10°C to 20°C. The material included hemlock and amabilis fir lumber treated with borate and chromated copper arsenate (CCA). After seven years of exposure, generally all of the treated material was found to be performing equally well, with some pieces showing residual signs of earlier superficial feeding or cosmetic damage. Attack was moderate on untreated controls.
A range of commercially available natural finish products were exposed to natural weathering at test sites in Vancouver, B.C. and Gulfport, Mississippi. One of the pre-treatments evaluated under these finishes was chromated copper arsenate (CCA) pressure treatment. After 28 months in test, the finishes over CCA-treated wood were subjected to a wipe test to assess their ability to seal in arsenic. Film-forming finishes provided a good barrier against leaching, while penetrating stains were less effective, although all finishes reduced dislodgeable arsenic compared to unfinished CCA-treated wood.
The key objectives of this project are to develop two-way technology transfer instruments that achieve a connection with specifiers, designers, builders, homeowners and maintenance supervisors and to explore opportunities for collaborative field studies of durability performance where information gaps exist.
The key objective of this project is to determine the major source of bluestain fungi and determine the mechanism of their dispersion in order to add value to wood products starting at the resource by providing strategies to prevent degrade of logs due to staining.
Fibre-reinforced wood systems are light, strong, stiff composites that can efficiently replace larger wood members and can be relied on to provide consistent mechanical properties.
This report is an introduction to fibre-reinforced wood systems for members of the Canadian wood products industry. It provides the motivation for reinforcing wood with synthetic fibres, and surveys the choice of materials and their uses. Numerous examples of current applications are discussed to demonstrate the strong and weak points of various approaches and examine the durability and management of fibre-reinforced wood products, as well as to indicate opportunities that exist for the Canadian wood products industry.
This report is intended to be a useful reference for the Canadian wood products industry, and assist future developments in structural and non-structural applications of fibre-reinforced wood products.
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.
Recipient Agreement Number: R04-013 Research Program
Vancouver, British Columbia
Western red-cedar (WRC, Thuja plicata Donn ex D. Don) wood was extracted sequentially with six solvents using two extraction methods. The extracts were prepared for subsequent bioassay and analysed by high performance liquid chromatography for known bioactive compound concentrations.
To focus identification of the extractives on those with bioactive properties, it was necessary to develop a micro-bioassay that would allow the biological activity of the unknown compounds present to be determined using minute quantities of each extracted constituent. The initial proposed technique utilised the loss of birefringence that occurs when decay fungi disrupt the crystalline cellulose structure as wood decays. Microtome sections of perishable sapwood were treated with microgram amounts of T. plicata heartwood compounds prior to exposure to decay fungi. The efficacy of the applied extract was then to be measured relative to the birefringence loss in untreated pine sapwood.
Validation of the technique required standardisation of a number of variables. Over 600 thin sections of ponderosa pine sapwood were cut and exposed to three different fungi, plus non-infected controls, under varying conditions of section thickness and orientation, media and growth conditions, viz, on grids or sterile microscope slides, with and without cover-slips, and with and without supplemental nitrogen, for six different incubation periods. Ultimately it was decided to test the extractives with two standard test brown rot fungi, Coniophora puteana and Postia placenta, using 25m radial sections which were sterilised, dipped in Abrams’s nutrient solution, and placed on a microscope slide prior to infection and incubation at 25 C, with a cover-slip placed over the inoculated section.
Analysis of the loss in birefringence was problematic and eventually abandoned due to time constraints. Towards the end of the project it was determined that the polarising filters in the microscope being used had been improperly manufactured. As a result, it was impossible to achieve 100% polarisation and we therefore could not examine loss in birefringence.
A commonly used antibiotic sensitivity test was modified to examine fungicidal efficacy of the extracts. Using 24-well tissue culture plates, four fungi were inoculated onto four media; one cellulose-based media was selected for use with Perenniporia subacida and Cephaloascus albidus isolated from a decaying second-growth WRC tree. Microlitre amounts of four known compounds dissolved in ethanol at three concentrations, plus the reference compound pentachlorophenol (PCP) and solvent controls, were pipetted onto paper disks and tested against the two fungi. Two of the extracts, ß-thujaplicin and thujic acid, plus PCP, were inhibitory to the fungi, verifying the methodology.
However, HPLC analysis of additional treated disks indicated that there was a substantial loss of chemical on the substrate over relatively short periods of time. This would indicate that the compounds were probably effective at lower concentrations than the targeted concentration. Volatilisation or decomposition when exposed to air and/or light was the likely cause of the observed mass loss of compounds. Recent tests have focused on the minimum time required for the ethanol solvent to evaporate when the extract is dispensed, so that disks may be rapidly moved onto the agar surface of the wells without any additional fungal toxicity from residual ethanol. A ventilation period of 30 minutes appears to be adequate for this. In addition, wood disks were found to be more effective than cellulose disks. In well tests, fungi grew well when wooden disks with ethanol were ventilated for 30 minutes. This test method will be used to bioassay isolated compounds.
The wood industry is facing some serious challenges in how end users view the long-term reliability of wood construction systems. The 1990s have seen the industry hit with a series of high-profile wood product failures due to decay, for example in North Carolina and coastal British Columbia. There are several efforts underway in North America and around the world focused on developing predictive models for moisture conditions in exterior wall systems. All of these models can predict temperature and wood moisture content change over time, but the consequences of those conditions in terms of decay are not yet predictable. While it is known that wood below 20% moisture content will not decay and wood above 28% moisture content will decay, fungal response to conditions between 20 and 28% is not well documented, particularly for North American fungi and wood species. Forintek Canada Corp. has a project underway to determine the time required for wood products to suffer detectable strength loss under a variety of temperature and moisture conditions. The focus is on sheathing as it is the last place to dry out after wetting events. Since this project was initiated, other researchers have become involved in this issue and it is therefore timely to review the state of the knowledge in this area. There is a considerable volume of work published and a limited amount of work underway but little of this is directly relevant to developing damage functions for hygrothermal models. The work underway at Forintek needs to be completed to define the time to initiation of decay under constant moisture conditions. Further work needs to be done to define the time to initiation of decay under fluctuating conditions. Data on the initial rate of decay under limiting conditions should also be generated from this work.
A group of 2x4 SPF samples was tested for bending stiffness in the Western laboratory of Forintek and then re-tested in the Eastern laboratory . Another group of 2x4 SPF samples was tested for bending stiffness in the Eastern laboratory and then re-tested in the Western laboratory. The bending stiffness tests were conducted on test machines set up in accordance with ASTM Standard D198-02. Additional bending tests were done according to ASTM D4761-02A using the “portable bending” machine in the Western laboratory and a modified Metriguard 312 bending machine in the Eastern laboratory.
Results from ASTM D198-02 bending stiffness tests showed a differences between the laboratories of 2.1% for the sample originating from the Western Laboratory and 1.5% for the sample originating from the Eastern Laboratory. The MOE bending test results were not adjusted to account for any increase or decrease in the moisture content of the specimens.