Canadian Forest Service Publications
Feasibility of composing green mountain pine beetle veneers. 2009. Dai, C.; He, G.; Xu, H. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. Mountain Pine Beetle Working Paper 2009-09. 18 p.
Issued by: Pacific Forestry Centre
Catalog ID: 30977
When mountain pine beetle logs are used to manufacture plywood and laminated-veneer lumber, veneer recovery can drop by 30%. Veneer composing is an effective and efficient way to improve veneer recovery, and the lower moisture content of mountain pine beetle veneers makes composing green veneers feasible and advantageous. This project studied the feasibility of composing green mountain pine beetle veneers using three gluing methods: taping, string-gluing, and fibre-gluing. Adhesive screening using the automated bond evaluation system indicated that a two-part polyurethane/emulsion polymer adhesive gave the highest bond strength, the highest curing speed, and the highest moisture tolerance. A one-part polyurethane adhesive showed relatively high moisture tolerance, but with lower bond strength and curing speed than the polyurethane/emulsion polymer adhesive. Green veneer composing by taping with the polyurethane adhesive was successful with veneer moisture content up to 60%. String-gluing with the polymer adhesive was also successful with moisture content up to 60% and with a shorter press time. Fibre-gluing was successful with the moisture content up to 40%. Shrinkage of composed veneers after drying was up to 2 mm for the veneer composed by taping and fibre-gluing, and over 2 mm by string-gluing. This gap may affect the quality of composed veneers. In general, green veneer composed by gluing was successful under appropriate conditions. Green veneer composing may improve mountain pine beetle veneer recovery by 20 %, improve drying efficiency, and reduce labour, saving up to $4.5 million per year for an average mill. Green veneers can be composed in current plywood mills with minor modifications to conventional dry-veneer composing.