Full-length through-boring: Effect on pentachlorophenol penetration and retention and residual strength of Douglas-fir poles

The effect of full-length through-boring on preservative treatment and wood strength was investigated on Douglas-fir poles. Through-bored poles had excellent preservative retention from the surface to the pith with most cores showing complete penetration. Breaking-point stress was slightly lower than the American National Standards Institute specification for Douglas-fir. No consistent pattern was noted between breaking stress and location of failure along the pole length. The excellent preservative penetration found in these poles, however, should result in little decline in strength with time in service. Thus, although the poles may originally have slightly lower but adequate strength, that level of strength should remain consistent throughout the service life of the structure. ©Forest Products Society 1999