(also termed: Beaverboard, Masonite, Upson board) These boards are made from wood-pulp and/or waste paper. The front presents a smooth hard surface, the back having a textured tooth resembling a reverse canvas texture. Suitable for oils if sized and primed, also for acrylics if grounded with acrylic primer. Sizes over 20 x 24 in need some kind of battening for support.