To retain access to European markets all green softwood lumber except cedar will have to be heat treated to a core temperature of 56°C. To reduce processing costs it may be possible to use thinner strips between rows of lumber than used in kiln drying, so that packages could be shipped with strips in place. This would eliminate unstickering and repackaging after treatment. To determine the effect of strip thickness on heating time, laboratory scale runs using 63 mm green hem-fir were compared using stickers 3, 6, 9.5 and 19 mm in thickness. Heating times increased as sticker thickness decreased. The 3 mm stickers produce too great a resistance to air flow and are not recommended. An increase in heating time of only 25 percent was found with 6 mm stickers compared to the standard 19 mm stickers. Further mill scale evaluation would determine if the costs associated with longer heating times with 6 mm stickers would be offset by the savings resulting from increased volume per kiln charge, reduced handling and repackaging costs.