Can be difficult to work with. The higher spots can be cut away on a table saw or jointer using a special jig. Cup Warping along the face of a board from edge to edge . This defect is most common of plain-sawn lumber. This defect can be caused when one board face dries at a faster rate than the other.
Stock can be difficult to work with.
You can try allowing the board to dry at the same moisture content under pressure, rip it into smaller pieces on a table saw, or use a jointer to remove the high spots. A dark, usually loose knot. This is caused by a dead branch that was not fully integrated into the tree before it was cut down. Can mar the appearance of the wood, fall out, become loose, or weaken stock. Should be cut out, around, or glued in place and filled with a wood putty.