Forest companies across Canada are interested in using laser scanners for scaling logs because it has potential for reducing scaling costs. Scanning logs over bark requires a method to obtain the under-bark diameter in order to calculate the solid wood volume. This report evaluates the methods of applying a bark factor to determine under-bark diameter. It also identifies new scanner scaling technologies for measuring bark thickness.
Debris management at logging sites and handling facilities is of increasing concern due to the volume of accumulated material and the constrained options for disposal. In March 2014, B.C. Timber Sales (BCTS) provided a timber sale on Maurelle Island that produced a large quantity of detached bark which originated from a 132-ha harvest area. Harvesting was during March 2014, and the predominant source of bark was from 41 150 m3 of Douglas-fir which accounted for approximately half the harvested volume (88 050 m3 total harvest volume). The bark accumulated at both a log storage area and on a transport barge during loading and unloading. The bark was disposed of along two dead-end spur roads (Figure 1). One of the spur roads has a small S6 stream (non-fish bearing) crossing through it. The disposal of logging debris (bark) along spur roads had not been considered or tried before by the Strait of Georgia Business Area of BCTS. The bark for Douglas-fir accounts for 30% by volume, which is the highest overall volume of bark for all softwood species (on average bark accounts for 10 to 15%).
Au début de 1990, quelques modèles d'ébrancheuses-écorceuse à fléaux étaient disponibles sur la marché en Amérique du nord et plusieurs prototypes étaient opérationnels ou en développement. Des résultats préliminaires décrivant la productivité et le rendement de deux modèles commerciaux d'ébrancheuses-écorceuses à fléaux obtenus lors d'études réalisés par FERIC sont présentés. Les modèles étudiés furent la Forest Pro modèle 23 et la Peterson-Pacific DDC 5000.
A mill test and a study were carried out to provide a benchmark as to what is the best debarker performance achievable on frozen wood with properly adjusted debarker settings and well-maintained equipment. The test results have shown that:
The fibre to bark ratio decreased to 12.7% from the 20.9% observed in a previous Forintek study of sawmills with average debarker performance.
The lumber value recovered from logs was 10.7% higher than that achieved with average debarking, and the corresponding lumber volume increase was 10.4%.
The debarker removed 97.3% of the bark volume.
The fibre loss was 1.2% .
For a sawmill processing 100,000 m3 of logs during a winter period of three months, losses attributed to poorly operated debarkers can amount to as much as $1.4 million.
The effects of different pressing variables were evaluated for the manufacture of hog fuel board made from western hemlock. In general, the hog fuel boards made at higher temperature and pressure exhibited better dimensional stability and durability properties. Pressing time was reduced with temperature ranging from 20 min at 260 C to 4 min at 315 C. It was demonstrated that good quality hog fuel boards could be produced using a high wood content of 65%. In all cases, the western hemlock hog fuel boards showed an average thickness swelling less than 10% after a 2-hour boil test. After the same treatment, OSB shows 50% thickness swelling and particleboard disintegrates. Preliminary results for bark / hog fuel boards made from three eastern species, white spruce, balsam fir and jack pine showed the boards exhibited excellent dimensional stability and durability properties. In the interests of furthering the preliminary market and economic feasibility investigations of bark board and in co-operation with Dr. A. Kozak and his 4th year marketing class (Dept. of Wood Science, UBC), exploratory analyses were done on four potential end uses. These were flooring, floor underlayment, roof shingles and furniture / cabinets.
The work presented in this report addresses the manufacture of bark board products on Forintek’s 15 x 15 –inch hot press. The properties of these bark board products including fire and decay resistance, fastener and weathering properties, VOC’s and formaldehyde emissions, dimensional stability and strength properties are discussed in the report. Some discussion on the mechanism of bark board chemical reactions is discussed. Results on catalysts to reduce pressing temperature and time, the potential to utilize recycled material as well as a preliminary market evaluation for bark board are also discussed.
Specifically using an optimized pressing schedule on the 15 x 15 – inch hot press at 260°C, spruce bark boards exhibited excellent internal bond strength and dimensional stability.
Results showed that by using 3% by weight of a catalyst, the pressing temperature can be reduced by 40°C in the manufacture of bark board.
Results showed it is feasible to use recycled plywood and OSB trim furnish up to 20% by weight in the manufacture of spruce bark board.
A preliminary marketing study indicated that the positive attributes of bark board showed strong potential of marketing a bark board product not only in North America but also in Japan.
Bark boards made from eastern and western species as well as catalyzed Douglas fir bark all showed substantially lower VOCs emissions compared to commercial unfinished MDF and particleboard panels. These bark boards also showed negligible formaldehyde emissions and were about one hundred times less than the 0.3 ppm emission limit set by the American HUD and voluntarily adopted by the North American Composite Panel Association. The VOCs emissions were driven off the bark boards during the manufacturing process. The higher levels of VOCs emissions during the pressing step would have to be considered when constructing a plant.
By overlaying spruce bark board with thin 1.5 mm birch veneers, the nail-head pull-through load increases by a factor of over four and is comparable to plywood and oriented strandboard.
Based on cone calorimeter test data, one-step birch veneer overlaid spruce bark board would exhibit a flame-spread rating in the range 60 to 70. This compares to a flame spread rating range of 140 to 220 for OSB, 90 to 120 for Canadian softwood plywood and a flame spread rating below 25 for fire-retardant wood. The cone calorimeter test data also showed the time to ignition for one-step birch veneer overlaid bark board is much better than most wood products.
Preliminary results showed that painted western spruce bark board samples showed good weathering properties.
Both Douglas fir and spruce bark boards showed good resistance to brown rot fungi.
The durable, dimensionally stable bark board products are unique compared to all other wood composite products in that they are manufactured without the need for expensive synthetic adhesive.
Logging operations conducted during the spring may encounter a greater amount of bark sloughing from cut trees than during other times of the year. The sap flow in a tree during the spring can loosen bark, and depending on the tree species, it can result in bark becoming detached more easily during machine handling. In March 2014, B.C. Timber Sales (BCTS) provided a sale on Maurelle Island that produced a large quantity of detached bark. The bark accumulated at both the log storage area and on the transport barge during loading and unloading. The amount of bark on the barge was too much for the offload facility to accept, so it was left on the barge for the return trip to Maurelle Island. The bark was disposed of along two dead-end spur roads.
