These are defects found in lumber that are caused by sawing and dressing lumber. The machining process to produce dimensional lumber puts a large amount of stress on wood. In trying to reshape a large uneven log composed with complicated grain patterns into usable lumber can cause reactions that produce low quality lumber.

Roller Check – Roller check occurs when a cupped board is mechanically flattened between roller planes. A light roller check in up to 2’ long, a medium roller check is between 2’ and 4’ long, and heavy roller check is more than 4’ long.

Skip – Skip is referred to as any area where the planer missed the surface leaving it roughed up. Skip is caused when the width or thickness of a piece is too small for the planer to remove all the rough surfaces.

Machine Burn – Machine burn is the visible darkening of wood due to the overheating of the knives usually because they are too dull. This defect can usually be removed by sanding.