Lumber GradingHardwoods are graded differently then softwood. Graders look at the wood at the wood to see what size rectangular shapes can be cut with no defects. This is called clear faced cutting. The waste and size of the clear cutting areas determines the grade. Grading goes like this:
FAS-First and seconds-No more than 16% waste and the worst side of the board is the side graded. The clear cutting cannot be smaller than 3 inches wide and 7 feet long or 4 inches wide and 5 feet long. The actual boards must be at least 6 inches wide and 8 feet long.
FAS-1 This grade is scored like FAS but on the best side of the board.
Selects are also similar but the boards can be as short as 6 feet and as narrow as 4 inches. Number 1 Common can have 33% waste and clear cuttings are 4 inches wide and 2 feet long or 3 inches wide and 3 feet long. The length of the board must be at least 3 inches wide and 4 feet long.
Number 2 or 3 Common have even more waste and are usually not used in furniture.
Of course there are exceptions to everything and lumber grading is no different. Quarter sawn boards can be as narrow as 5 inches in walnut and butternut and still be classified as FAS.
The long and short of it is that hardwood is graded for useful wood and softwood is graded by appearance