Species and commodities that are difficult to consistently and uniformly penetrate with preservatives are required to be incised prior to treatment. Incising is required in all faces except for lumber with patterned edges where incising is required on wide faces only.

Incising is required for the following species:

          Coastal Douglas-fir • Hemlock • Hem-fir • Spruce • Lodgepole Pine • Jack Pine • Redwood • Spruce-Pine-Fir

Incising patterns of sufficiently high density and depth to obtain the required uniformity of penetration are required. A minimum of 750 incisions per square foor is required except when using ammoniacal preservatives, where fewer incisions are required.