Domestic hardwood lumber found at sawmills meets different quality levels or grades as specified by the National Hardwood Lumber Association (NHLA). The basis for this wood grading is the number and size of defect-free clear cuttings in a board, as summarized below, Thickness is not a consideration, though with some species worm holes, gum pockets, and stain are acceptable. FAS (First & Seconds) lumber grade. This premium grade represents the finest lumber yield in a log. Generally, the minimum size board is 6" wide by 8' long which yields a minimum of 83 1/3% clear cuttings on its poorest face. F1F (FAS One Face) lumber grade. The best face grades as clear FAS; the worst, as #1 common, containing some knots. Selects lumber grade. Close to a FAS board. A Select board must be a minimum of 4" wide and 6' long and yield a minimum of 83 1/3% clear cuttings, but only on one face with #1 common on the worst face. #1 Common . An economical choice f...