In view of the long-standing nature of the Canada-U.S. softwood lumber dispute, this literature review examines opportunities for softwood products that are currently not affected by the dispute. This includes non-commodity softwood products for the U.S. market and softwood lumber opportunities in the domestic Canadian market, Asia and Europe.
Alberta Alliance Project No. 5130-05 pertaining to softwoods - Utilization; softwoods - Markets
Powder and liquid phenol-formaldehyde (PF) combination binder system has been commonly used in North America for oriented strand board (OSB) manufacturing. This binder system has shown its suitability for improving resin efficiency and bond quality as compared with either powder PF (PPF) or liquid PF (LPF) resin. This study was conducted to investigate the effect of resin application sequence (LPF-PPF-LPF, LPF-PPF, PPF-LPF), resin content (3.0%, 5.5%, 8.0%), and PPF/LPF combination ratio (50:50, 65:35, 80:20) on strand board performance. Board properties evaluated include internal bond (IB), thickness swelling (TS), water absorption (WA), dry and wet modulus of rupture (MOR), dry modulus of elasticity (MOE), edgewise shear, and compression shear strength. In addition, a non-destructive test method (TROBEND) developed at Forintek was also used to measure the modulus of elasticity (MOE) and shear modulus of elasticity (G).
Response Surface Methodology (RSM) was used in the experiment design. Significant response surface models were established for individual panel properties, including the linear model for IB, dry MOR, dry MOE, and compression shear, as well as the quadric model for TS, WA, and wet MOR, and 2FI (two factor interaction) for edgewise shear. ANOVA for response surface model indicated that the resin content was a significant model term for IB, TS, dry MOR and MOE, wet MOR, and compression shear properties. An increase in resin content improved these board properties. Powder/liquid ratio was a significant model term for TS, WA, and wet MOR. Resin application sequence was not a significant model term for any panel property, but its interaction with resin content was a significant model term for edgewise shear property.
In most cases, the interactions between experimental variables were not significant model terms for predicting panel properties, but they still revealed some trends. Regarding Sequence 3 (PPF-LPF), 50:50 PPF/LPF ratio (lower level) resulted in higher IB, dry MOR, and compression shear, while 80:20 PPF/LPF (higher level) yielded lower WA and higher dry MOE. For Sequence 2 (LPF-PPF), 65:35 PPF/LPF ratio (middle level) favoured TS, while 50:50 PPF/LPF ratio (lower level) favoured wet MOR. Sequence 1 (LPF-PPF-LPF) combined with 50:50 PPF/LPF ratio (lower level) also gave lower WA values. In general, an increase in resin content improved the board properties with the above combinations. In addition, Sequence 3 (PPF-LPF), with 3.0% resin (lower level), yielded higher edgewise shear strength regardless of resin application sequence.
An attempt was made to correlate the panel mechanical properties measured using both destructive and non-destructive test methods. The strongest correlation was observed between IB and compression shear (R2=0.70), followed by TORBEND G with modulus of elasticity (TORBEND MOE) (R2=0.40), and TORBEND G with compression shear (R2=0.28) and with IB (R2=0.26). However, no correlation seemed to exist between MOE (static bending) and TROBEND MOE.
An image analysis indicated that an increase in resin content significantly increased resin coverage on strand surface. At each resin content (3.0%, 5.5%, and 8.0%), a decrease in PPF/LPF ratio in Sequence 1 (LPF-PPF-LPF) or an increase PPF/LPF ratio in sequence 3 (PPF-LPF) seemed to result in higher resin coverage. Resin coverage seemed to correlate to TS (R2=0.45), IB (R2=0.42), compression shear (R2=0.39), TORBEND G (R2=0.39), dry MOR (R2=0.25), wet MOR (R2=0.25), and dry MOE (R2=0.18). However, resin coverage did not seem to correlate to WA, TORBEND MOE, or edgewise shear properties.
Although significant volumes of Alberta's trembling aspen resource are being used for pulp and for oriented strand board production, the species can be accurately referred to as "under-utilized" with respect to the production of solid wood products. It is well documented that the aspen's external indicators of quality correlate poorly with internal characteristics, making it particularly difficult to identify suitable sawlogs. This means that the greatest challenge around cutting aspen into solid wood products continues to be the identification of logs that are of suitable quality.
This report details the development of an experimental log grade rule for use when evaluating aspen logs. The rule was developed to more accurately segregate those aspen logs that can be profitably cut to high-valued solid wood products from those more suitable for conversion to oriented strand board or pulp. In the first phase of the study, three samples each consisting of thirty logs that met the revised criteria were sawn, and lumber grade yields were calculated. Although the results were encouraging, it was recognized that larger samples needed to be evaluated. To this end, in the second phase, additional, larger samples were sawn, and grade yields again determined. Test results from the second samples largely replicate the first samples and show that logs that meet the revised criteria will more consistently yield high grades of lumber.
The question of available volumes of the experimental log grade is also an important one. This report describes evaluations of aspen logs in inventory at three large manufacturing facilities in Alberta. It is inferred that between 1.5% and 3.5% of the log volume in sampled inventories meet the criteria for new log grade. Recommendations for follow up work include: detailed case studies that consider all of the economics of building and operating an aspen grade mill; a more comprehensive analysis of harvested volumes of aspen in order to more accurately estimate the available volumes of sawlogs meeting the standards for the new log grade rule; an analysis of the costs and benefits of using x-ray scanning technology to sort out aspen sawlogs from those more suitable for pulp or oriented strand board production; and an analyis of remanufacturing opportunities based on estimated yields of cuttings from the experimental log grade.
AFRI - AFRI-711G-05 pertaining to Populus - Utilization; Value added - Alberta; Grading - Logs
One of the major constraints to the growth and development of a value-added sector for trembling aspen in the solid wood industry concerns the inherent variability in quality of the resource. Much of the resource is simply not suitable for the extraction of lumber grades required to service markets for higher valued wood products, and those logs that are suitable for grade extraction are often difficult to identify. Recent market research details an interest in higher valued grades of aspen, particularly in Asia. On the basis of that market research it is worth investigating the predictive value of an alternative system of identifying aspen logs well suited for the production of high-grade lumber.
This report details the conception and application of an experimental log grade rule for use when evaluating samples of aspen logs. The rule is intended specifically to separate high valued aspen sawlogs from those more suitable for conversion to oriented strand board or pulp. The log grading system presently used to evaluate most hardwood logs that are graded, one developed by the United States Forest Service, has been shown to do a poor job in estimating the value of aspen logs. The new log grade rule was based on the existing system, which was modified slightly to reflect some inherent characteristics of aspen. Three samples each consisting of thirty logs that met the revised criteria were evaluated. Test results reported here show that logs that meet the revised criteria will more consistently meet higher grades of lumber; however, more work must be done to confirm the predictive value of the new rule. In addition the issue of available volumes of logs meeting the revised criteria must be addressed.
AFRI - AFRI-700VA-03 pertaining to Populus - Utilization; Value added - Alberta; Grading - Logs
This project was initiated to provide technical assistance to the Alberta wood drying industry. The specific objective was to identify opportunities to improve product quality through modification of the drying schedules. Seven mills representing almost 50% of the solid, softwood lumber production in the province were selected for the project. All mills provided a great deal of cooperation and commitment to the project was excellent. In general, lumber drying operations in Alberta are in good physical condition and operating personnel have a sound knowledge of basic drying concepts.
In general, drying schedules were found to be quite harsh. the specific concerns at most mills related to too rapid a heat-up rate and extremely low relative humidity at the end of the drying cycle. Most of the schedule modification called for more gradual and controlled heat-up rates with higher wet-bulb temperatures. The objective of this modification is to avoid setting up conditions othat promote variability in moisture content from board to board. Higher relative humidity is required at the end of the drying cycle to avoid over-drying faster drying boards. Achieving a reduction in final moisture content variability and a higher overall average moisture content should be the objective of drying schedule modifications.
Mill visits were used not only to review drying schedules but also to conduct a brief inspection of drying practices and equipment. It would be unproductive to identify schedule modifications if there were obvious shortcomings in other areas of the operation that would make it difficult to implement or over-shadow the effect. The primary concern with drying equipment is the leakiness of the structures. A common recommendation to mills was to tighten up kiln doors and walls in order to retain more moisture in the kiln environment. Another area of concern was related to lumber handling operations. Most problems in this area could be addressed through educating and training staff working at stackers, handling material in the yard, or preparing loads for the kiln.
Logging and log storage practices at all of the mills visited has a serious and detrimental impact on the drying operations. At most times of the year, operators are having to deal with a wood supply that has a mix of initial moisture content conditions. Most mills seem to manage the small percentage of balsam fir in their mix effectively. Some future gains may be achieved through refined presorting techniques that take into account initial MC variability as well as differing drying characteristics between species.