Medium Density Fiberboard (MDF) is a type of home-improvement building material that has uses similar to that of plywood and particleboard. First manufactured industrially in the 1980’s, MDF is composed of small wood fibers, binding resins and a small amount of paraffin wax. The application of heat and pressure to these materials produces a mat of uniform thickness that is cut to size (normally 4” x 8” in the US; 124 x 249 cm). MDF has a higher density than both regular plywood and particleboard; the density is controlled during the extrusion/pressing stage of production and the typical density of MDF has a range of 31–62 lb/ft3 (500–1000 kg/m3). The wood fibers used in the production of MDF normally come from softwood sawdust/wastes, but other materials such as hardwoods, cardboard, newsprint and even old telephone books can be used as the substrate material. There is also a variety of binding resins used, which include phenolic, melamine, isocyanate, urea-formaldehyde (UF; also the most common resin used) and formaldehyde.
Several of the properties of MDF make it an ideal material for furniture manufacture. The surface is incredibly smooth so MDF can take paint much better than real wood and could also be used as a backer material for veneer. It is economic from both a financial and environmental standpoint; it costs less than plywood and much less than real wood while the manufacturing process utilizes recycled/excess materials thereby saving trees. MDF also resists seasonal movements due to heat and moisture that plague real wood. It also machines very well. However, MDF also suffers from several drawbacks. MDF is hard to repair once dinged or nicked up. MDF also doesn’t take nails very well, often ‘exploding’ out of the opposite side (much like laminates do). While MDF is resistant to normal fluctuations of humidity, direct contact with water will cause MDF to swell, likely ruining that piece of the board.
However, one of the main concerns surrounding the use of MDF focuses on the very resins used in its manufacture. Cutting MDF releases micrometer-sized wood particles that irritate the eyes and upper respiratory tract. This health hazard is easily avoided with the use of proper personal protective equipment (such as a respirator) and proper working conditions (including adequate ventilation and dust control systems). While the formaldehyde from both formaldehyde and urea-formaldehyde (UF) resin binders also irritates the eyes and upper respiratory tract, the most significant health concern associated with these binders is their potential as a carcinogen. However, a definitive link between these resins and cancer has not been established; the Material Data Safety Sheets (MSDS) for both resins only list them as ‘potential’ carcinogens or ‘suspected’ of causing cancer. The UF MSDS even went further and stated the link was ‘based on limited evidence’. Despite the lack of a definitive link, those who work with MDF should follow any/all prudent safety precautions when handling MDF. While there no way to eliminate risk altogether, adhering to straightforward, standard safety precautions should allow people to work with (and discover the many wonderful benefits of) MDF as a building material without a fear of taking an unnecessary health risk.