Individual tooth and needle incisions were made on radial and tangential surfaces of white spruce and jack pine heartwood test samples. The samples were pressure-treated with CCA preservative and then dissected in various planes to examine patterns of preservative penetration. Lateral movement of preservative from incisions was generally greater in the radial than in the tangential direction (average R/T ratio about 1.5). Longitudinal movement was in the range of 15 to 20 times that of lateral movement. Ray tissue facilitates movement in the radial plane, but difficulty is encountered in traversing latewood bands. An individual tooth incision resulted in a larger zone of treated wood but also in a greater amount of wood tissue damage than a needle incision. When compared as ratios of treated wood area to damaged wood area at a depth of 9 mm beneath the original treated surface, needle incisions were decidedly superior. For an equivalent degree of preservative treatment, conventional incising teeth damaged about ten times the amount of wood tissue as did incising needles
