Thus, as a flat-grain board is sawed from the face of a log it tends to curve away from the headsaw. No particular problems develop. Sometimes, however, if the log is sawed deep or if a more or less full width board is cut from around the heart area, it will develop deep splits in the ends. These splits are from growth stresses. They occur on a sporadic basis, and are not the result of mishandling the lumber during drying.
Splits can also develop from tension wood.
Tension wood forms in the upper side of leaning hardwood trees. The presence of both surface and end checks is relatively easy to determine. For surface checking, cut one-inch strips across the width of the board and away from the ends and other obvious defects or grain distortions. If they do not, the section is free of checks. Successive cuts will help determine how deep the checks penetrate the piece.