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(6) m(2) (500 x 10(3) acres) of yellow-cedar in southeastern Alaska. Th ese declining yellow-cedar stands contain a mixture of dead and living tree s, and because of their gnat resistance to decay, these dead trees can rema in standing for as long as 120 years after death. Ln the interest of better utilizing the affected timberland and the highly durable, potentially valu able yellow-cedar, a cooperative study was done to determine if deteriorati on had occurred in the mechanical properties of salvaged yellow-cedar. Face d with reports of unsatisfactory adhesive bonding from potential users and varying bondability reports of yellow-cedar from the United States Departme nt of the Navy, Bureau of Ships, the study reported herein investigated whe ther phenol-resorcinol-formaldehyde (PRF) adhesive could develop durable bo nds to the salvaged yellow-cedar. Test results of adhesive bonds in lumber laminates demonstrated that resistance to delamination, sheer strength, and wood failure exceeded requirements of ASTM D 2559, which is a specificatio n for adhesives used in structural laminated wood products exposed to exter ior service conditions. Comparisons of data from this study and two studies by the Bureau of Ships indicate that bondability of yellow-cedar was not c ompromised because the lumber had been salvaged from 500-year-old trees tha t had been dead for 14 years. Wood products laminated from salvaged but dur able yellow-cedar should command a premium in the marketplace, particularly for marine construction.