Hardboard

Panels of shredded wood that is glued together with its own natural adhesive called lignin. It is excellent as a painting surface. It resists warping and swelling. It is made in two types, tempered and untempered. The tempered is impregnated with oil to aid in resisting moisture. It is harder and has a smoother surface. The surface of the tempered should be sanded to roughen it before priming. Both surfaces are good for painting.