This study evaluated the effect of two different incisors followed by chromated copper arsenate pressure treatment on the bending strength and stiffness of No. 2 and better nominal 2 x 4 inch (38 x 89 mm) spruce-pine-fir and hem-fir lumber. The double-density incising method, developed at Forintek, allows SPF to meet the CSA O80 wood preservation standards. The high-speed incisor was developed by Forintek for operation immediately behind the planer in a sawmill to produce a treatable lumber product. The prototype tested here employed two solid rollers to lay down two superimposed patterns of incisions at a density of 17500/m2. Approximately 2900 specimens of SPF and 1200 specimens of hem-fir were sorted into nine and four matched groups, respectively, according to their average flatwise modulus of elasticity values tested in centre point bending. The matched groups were then given various combinations of drying, incising and pressure treatments. Bending strength properties were tested. It was found that kiln-dried SPF and green hem-fir commercial dimension lumber, treated by the above processes, can be safely used for all structural purposes for which preservative treatment is required.