Bondability of salvaged yellow-cedar with phenol-resorcinol adhesive and hydroxymethylated resorcinol coupling agent

A serious mortality problem affects about 65 percent of the estimated 2.02 x 10 sup6 m2 (500 x 10 sup3 acres) of yellow-cedar in southeastern Alaska, These declining yellow-cedar stands contain a mixture of dead and living trees, and because of their great resistance to decay, these dead trees can remain standing for as long as 120 years after death. In the interest of better utilizing the affected timberland and the highly durable, potentially valuable yellow-cedar, a cooperative study was done to determine if deterioration had occurred in the mechanical properties of salvaged yellow-cedar. Faced with reports of unsatisfactory adhesive bonding from potential users and varying bondability reports of yellow-cedar from the United States Department of the Navy, Bureau of Ships, the study reported herein investigated whether phenol-resorcinol-formaldehyde (PRF) adhesive could develop durable bonds to the salvaged yellow-cedar. Test results of adhesive bonds in lumber laminates demonstrated that resistance to delamination, shear strength and wood failure exceeded requirement of ASTM D 2559, which is a specification for adhesives used in structural wood products exposed to exterior service conditions. Comparisons of data from this study and two studies by the Bureau of Ships indicate that bondability of yellow-cedar was not compromised because the lumber had been salvaged from 500-year-old trees that had been dead for 14 years. Wood products laminated from salvaged but durable yellow-cedar should command a premium in the marketplace, particularly for marine construction.

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