Medium board is manufactured from lignocellulosic fibre (e.g. wood, straw, bagasse) in a density range of 400 kg/m³ to 900 kg/m³. Only panels with a density ≥ 560 kg/m³ are suitable for structural applications. Most medium boards are produced in a "wet process". In these medium boards, one face is rough due to the use of a mesh screen for dewatering. Boards manufactured by the "dry process" exhibit smooth surfaces on both sides. The panels are bonded primarily by felting of the fibres and their inherent adhesive properties . Usually, only small amounts of a synthetic binder are added to the fibres. By incorporating additives (e.g. hydrophobing agents, fungicides, fire retardants) or post-treatments certain properties of the board can be altered.