Teak (Tectona grandis) pressure treated with an oil-borne preservative was investigated to find its usefulness as transmission poles. The pole size round Teak was found to contain an average of 45 percent sapwood which is readily perishable by wood destroying organisms. Teak poles were treated by the Bethel full-cell process using varying pressure and duration to evaluate their effect on the penetration and retention ofthe preservative mixture of 40 : 60 creosotelight diesel oil. With the increase of both treating pressure and time the increase in penetration was not found to be statistically significant. The retention, however, significantly increased with the increase of pressure but the increase of time could not produce any significant effect.

A penetration of 1.57 cm with retention of 174.64 kg/m³ of treated sapwood could be obtained by using 8.81 kg/cm² pressure for 3 hours. This penetration is considered adequate to protect the sapwood region of the pole.