Effect of log rehydration on quality of OSB strands manufactured from beetle-killed lodgepole pine

• Published in: Forest products journal 2007, Vol.57 (1-2), p.35-42
• Main Authors: Feng, M.W, Knudson, R.M
• Format: Article
• Language: English
• Subjects: Applied sciences; bark; bark beetles; Degradation and preservation; Dendroctonus ponderosae; Exact sciences and technology; Forest products industry; Forests; gray-stage logs; heartwood; Insects; logs; Lumber industry; Manufacturing; Mechanical woodworking and drying; Moisture content; oriented strandboards; Pinus contorta; Polymer industry, paints, wood; product quality; Production costs; Properties; Properties and testing; Quality; Quality management; rehydration; Sealing compounds; storage; Studies; Timber; water sprinking; Waxes; Wood; wood fibers; wood moisture; Wood. Paper. Non wovens
• ISSN: 0015-7473; 2376-9637

A study was carried out to examine log rehydration as a means for improving the quality of OSB strands manufactured from lodgepole pine (Pinus contorta Dougl.) killed by the mountain pine beetle (Dendroctonus ponderosae Hopkins). The gray-stage mountain pine beetle-killed (MPB) logs used in this study had little bark, were heavily checked and had relatively even moisture gradients, ranging from approximately 15 percent to 25 percent moisture content (MC). Their average dry SG (0.447) was about the same as that of freshly cut lodgepole pine used in the study for comparative purposes. Water sprinkling was found to be an effective method for reducing the production of fines and increasing the proportion of larger strands from MPB logs. The generation of fines during stranding was reduced by 28 percent after 10 days sprinkling, by 30 percent after 20 days sprinkling and by 35 percent after 30 days sprinkling. After 10 days sprinkling the volume of fines generated during stranding approached the level achieved when stranding freshly cut lodgepole pine. Study results suggested that heartwood MC near the fiber saturation point was sufficient to reduce fines and increase the amount of large strands. Water sprinkling was effective particularly in increasing MC in the outer sapwood portions of the logs. The heartwood portions of the logs required longer for their MC to approach the fiber saturation point. There is high potential for improvement of log conditioning to increase moisture uptake in the inner portions of MPB wood. Further development of industrially viable log rehydration methods is strongly recommended.