The face of a plank may contain unlimited sound sapwood. Colour variation is prominent. Small burls, light brown streaks, restored knots up to 25mm, properly filled open checks and wormholes, slight imperfections in face work (torn grain) and burns are admitted. When stained in a dark colour, the surface appears uniform in shade and texture, making knots etc barely discernible. 1 Common is a tasteful floor where prominent variation is expected.