Category – Friction This method uses only two pieces – the plow stick and plow board (hearth board). Shown here is HAU wood from Hawaii, which is a member of the hibiscus family. The board is prepared with a slight groove that is about 6″ long. The stick is sharpened to a narrow but thick chisel point, and is rubbed along the groove, slowly at first but gradually faster while adding more pressure. Eventually, this action creates dark brown char at the end of the groove which, as it collects into a small mound, builds up heat to a point where a live coal is created.