Tempered Masonite is a specific type of Masonite. It is a "tough, high-density hardboard with superior strength and resistance to impact and water absorption," according to Australian-based distributor Gunnersen.
Tempered Masonite is made by infusing oil into the wood particles to form a stronger hardboard that is more resistant to wear, tear and water. However, the tempering process does not allow certain types of paint, such as gesso or water-based paints, to adhere to the board properly.
This may cause a painting done on tempered Masonite to flake and break down after several years.
Because of its durability and water resistance, tempered Masonite has many building applications. It can be used as flooring for theater and dance stages, as a wall lining for high-moisture areas or in the construction of outdoor signs.