Canadian Forest Service Publications
Maximizing value recovery from mountain pine beetle-killed pine for veneer products. 2005. Wang, B.; Dai, C. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. Mountain Pine Beetle Initiative Working Paper 2005-09. 33 p.
Available from: Pacific Forestry Centre
Catalog ID: 25426
Laboratory, pilot plant and mill tests were conducted to quantify the impact of using mountain pine beetle (MPB)-killed logs on veneer manufacture, and to determine optimum manufacturing strategies for conditioning, peeling, and drying to recover higher veneer value from this resource. It was found that: Proper log conditioning is key to improving veneer recovery from MBP logs. Conditioning MBP logs at 120 1350F (49 570C) pond temperature with a target core temperature of about 800F (270C) helps reduce ribbon breakage, and therefore reduces the volume percentage of random veneer. In addition, the veneer breakage is caused by cracks and splits in the radial and longitudinal directions due to log dry-out: Lathe settings also have a pronounced effect on veneer quality and veneer recovery. A proper lathe setting with a compression ratio (CR) of about 13% is recommended to help peel higher quality veneer and reduce the breakage of the veneer ribbon: Compared to the control green veneer, MBP green veneer has lower moisture content (MC) and smaller MC variation. In general, MBP veneer can be clipped narrower with an equivalent of 1% increase in recovery because of smaller width shrinkage, and be sorted more accurately requiring only two green sorts: heart and light sap. In particular, the MBP light sap sort is comparable to the control heart sort. MBP veneer can further be dried faster with a reduction in drying time by about 25% for the heart veneer and about 35% for the light sap veneer. Despite about 1% increase in recovery from veneer clipping and about 27.5% increase in productivity from veneer drying, the recovery of MBP logs is about 8% lower than that of control logs due to higher percentage of narrower random sheets and waste from peeling, and increased manual handling and composing. As well, the color of bluestain in MBP veneer is lightened after drying, but it still causes interference with the visual grading systems. Since MBP wood is drastically different from non-mountain pine beetle wood in terms of MC and subsequent processing characteristics, it is recommended that the MPB wood be sorted in the log yard. Such sorting is warranted with significant savings from increased recovery and productivity as the proportion reaches about 10% of the logs procured.