Medium Density Fiberboard (MDF)
What is MDF? What is Medium Density Fiberboard?
An engineered wood product commonly referred to shortly as MDF. These composite wood panels are made by reprocessing fine wood particles of sawdust from both softwood and hardwood trees. The particles are fused together with a glue or resin which is cured under high pressure and heat. Chemicals used in the manufacturing process make MDF termite-proof. However, because poisonous urea-formaldehyde is also used during production, MDF is not considered an eco-friendly product even though it is made from recycled wood.
MDF is made up of two dense faces with a relatively soft inner core, so using a countersinking drill bit before driving in a screw will help eliminate splitting, cracking or the possibility of the screw head snapping off before it sinks into the MDF. To avoid drilling all together, a power nail gun is suggested, as hammering in a nail could bend the nail or push a mound of fiber to the surface of the board. The small particles in MDF make the flat panels easy to cut and reshape, however, because of these small particles cutting MDF is a very dusty job, breathing protection should always be worn and it is best to cut it outdoors if possible.
While MDF can withstand some humidity or moisture, it is susceptible to water damage. If exposed to water the fine particles will degrade and cause irregularities in the surface or even swell up to twice its size. Once this happens it cannot be repaired.
MDF boards are sold in a variety of lengths and widths, with thicknesses from ¼” to 2”. The most common size board sold is a nominal 4’ x 8’, but boards are oversized by 1” so the actual size is 49” x 97”. MDF board is relatively heavy, with a 4’ x 8’ x ¾” MDF board weighing about 100 lbs. Despite the weight MDF needs to be handles with more care then lumber or plywood, because of the soft inner layers, MDF corners can crush easily.
MDF is frequently used by furniture and cabinetmakers as the core material because it is inexpensive, smooth, and paints well or can be covered with a laminate. However, it is not a stiff as plywood and can sag over time.