Medium-density fiberboard (MDF) is an engineered wood product that was developed commercially in the 1980s. This wood product is formed by breaking down wood (usually a small log) into wood fibers or clumps of fibers, similar to the paper-making process. The fibers are then mixed with an adhesive, and sometimes also with wax. These fibers are then assembled into a thick mat, which is then heated and pressed together to the desired thickness. This process rapidly removes any moisture and causes the adhesive to strongly bind the fibers together.

Low density fiberboard , which is used for products such as ceiling tiles, has no adhesive and does not require a high pressure press. In fact, the fibers are held together merely by their intertwining strength and density is low. In contrast, high density fiberboard , which most of us know more commonly as Masonite, gets so hot in the press that the natural adhesive within the wood is activated. High pressure is also used to create a high density board.

The properties of MDF are controlled primarily by the density of the final product and the amount of adhesive used. This certainly means that all boards are not the same, even if the pieces have the same physical size.

The typical density of MDF is 40 to 50 pounds per cubic foot (600 to 800 kg per cubic meter). Although the higher density board is heavier, it is also stronger and the edges machine better.

The ultimate strength of MDF will vary with the particular product characteristics, but a typical minimum value is 3,500 psi with an elasticity value of 0.35 million psi. Eastern white pine lumber values (average and not minimum; for clear wood) are 8,600 psi and 1.24 million psi. A middle grade and density of particleboard has minimum values of roughly 2,100 psi and 0.32 million psi. Although MDF is weaker than lumber, the basic question is whether the high strength of lumber is required for a particular use.

Applications for MDF are almost unlimited, and include drawer bottoms, backs of cabinets and center panels in framed doors. In building interiors, thin MDF can be used for wall and ceiling paneling, as skins for flush doors, partitions, lightweight doors and exhibition paneling. Thin MDF has found its way into novel applications such as shoe making, motor vehicle interior parts, toys, and blades for electric ceiling fans. MDF is also used as core material paneling has a face laminated with veneers, printed surfaces, vinyl and low-pressure laminates. A popular use is for the core for laminated flooring; such flooring is widely available.

For technical information, including performance standards, contact the Composite Panel Association (18922 Premiere Court, Gaithersburg, MD 20879). In addition to providing technical information, they have an excellent publication describing the MDF performance standard A208.2-2002.