- product quality:
Quality of processing: the surface of the floorboard must be smooth, no burls, no lack of dimension, no lack of tongue or groove. The tip of the tongue or groove must be perpendicular with the board side.
Grade a:
(free from any defects): no oil spot, no crack, no twisting, no knots, no blue stains, no sapwood, no center heart, no pin holes/worm holes
Grade b:
Accept some small defects: small healthy knot below 10mm in diameter and limited quantity, small crack, pin/worm holes buts no sapwood and center heart.
