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 ex cellent preservative retention from the surface to the pith with most cores showing complete penetration. Breaking-point stress was slightly lower tha n the American National Standards Institute specification for Douglas-fir. No consistent pattern was noted between breaking stress and location of fai lure along the pole length. The excellent preservative penetration found in these poles, however, should result in little decline in strength with tim e in service. Thus, although the poles may originally have slightly lower b ut adequate strength, that level of strength should remain consistent throu ghout the service life of the structure.