Medium-density fiberboard, commonly known as MDF, is one of several engineered wood-product panels used in the construction trades, furniture-making, and similar applications. Like similar sheet-good materials, such as plywood, particleboard, and OSB (oriented strand board), MDF is sold in large flat sheets of various thicknesses, and it can be cut and shaped using ordinary woodworking tools.
Any home built after the late 1980s probably has a considerable amount of MDF in its painted woodwork, its cabinetry, its furniture, and sometimes in its structural walls and floors. For many construction and furniture applications, MDF and plywood are equally acceptable, though plywood usually gets the nod where strength is critical, while MDF is more affordable and a better choice where the surfaces need to be painted. Unlike particleboard, with which it is sometimes confused, MDF has a smooth, dense surface that is ideal for painting.
What Is Medium Density Fiberboard?
Medium density fiberboard, or MDF, is a manufactured product composed of wood fibers mixed with resins and wax, and pressed into flat panels under high temperatures and pressure. MDF sheets come in thicknesses from 1/4 to 1 inch, and full sheets are typically 4 x 8 ft. in size (actual size is 49 x 97 inches). It is used as a building material in residential and commercial buildings and in cabinetry and furniture-making.
How Medium Density Fiberboard (MDF) Is Made
Medium-density fiberboard (MDF) is made by combining pulverized raw wood fibers with wax and resins, then heating and compressing the mixture to form extremely durable panels that can be used in diverse ways in construction and furniture-making. MDF is similar to plywood and is used for many of the same purposes, but the panels have no visible grain, since they are made from pulverized wood fibers rather than thin layers of actual wood, as is the case with plywood. Viewed on edge from up-close, MDF panels will appear to be uniform through their thickness—not layered in the way that plywood is manufactured.
Most commonly, MDF is sold in large sheets of various thicknesses that are used for many general construction purposes, but MDF is also found in special types and in products with different names:
- Beadboard is a type of MDF made with faux tongue-and-groove patterns. It is often used to make easy, inexpensive wainscot treatments and other wall paneling effects.
- Slatwall is a particular type of MDF panel that has deep-lipped grooves. These panels are often used for commercial display walls or for special shelving or storage systems.
- Extira is a particular brand of MDF that uses a special manufacturing process that allows it to be used in exterior applications. It has unique water-, termite-, and rot-resistant qualities.
- Moisture-resistant MDF makes use of special resins that make it a good choice in bathrooms, kitchens, and floors, where high humidity can cause standard MDF to swell.
- Fire-retardant MDF is often specified where construction needs to have extra fire resistance. Most commonly, it is seen in commercial buildings.
- Ultralite MDF weighs 1/3 less than standard MDF, so it is popular for use in theater sets or tradeshow booths, where structures must be periodically assembled and disassembled.
- Bendy MDF is processed in a manner that allows the panels to readily curve. Architects often specify this material to create curved walls and trim.
MDF vs. Particleboard vs. OSB (Oriented Strand Board)
MDF, particleboard, and oriented strand board (OSB) are all types of engineered sheet goods used in the construction and furniture trades. They are often confused with one another, but they have quite different properties and are preferred for different uses.
- Medium-density fiberboard (MDF) is made from pulverized wood fibers blended with resins and pressed into sheets under temperature and pressure. These are extremely heavy and strong construction panels that can be used in many of the same ways as high-grade plywood. The surface of MDF is very smooth, making it excellent for use in painted or veneered cabinetry and furniture.
- Particleboard is made from sawdust and very tiny wood chips blended with resins pressed into sheets under temperature and pressure. The panels are lighter than MDF and have less strength. Viewed on edge, particleboard panels have a rough, irregular texture because of the various particle sizes. Particleboard is an inexpensive building product that is generally used as a replacement for plywood or MDF in situations where appearance and strength are not critical factors. Particleboard is sometimes known as low-density fiberboard.
- Oriented strand board is made from relatively small wood strands bonded together in horizontal layers with waterproof glues. Unlike MDF and particleboard, the individual wood pieces are clearly evident in OSB. These panels are most often used in roof and floor sheathing, in much the same way as plywood is used. But OSB generally does not have the same strength value as either MDF or plywood, and its rough texture does not readily accept paint.
Uses for Medium-Density Fiberboard
MDF is an exceedingly versatile building material that is strong, durable, affordable, and consistent to work with. Among its many uses:
- Cabinets and shelves
- Decorative projects
- Speaker boxes
- Laminate countertops
- Doors and door frames
- Tradeshow booths and theater set construction
MDF, as a more affordable product, has replaced plywood in many applications, especially if the project or surface will be painted. The smooth surface that so readily bonds with paint will also bond well to wood and laminate veneers applied to it. A great many furniture pieces that appear to be solid hardwood actually have core carcasses made from MDF, which is then covered with hardwood veneer. Most laminate countertops use MDF for their cores. The only disadvantages to MDF are its weight—it is a heavy material—and it does not hold screws and nails as firmly as plywood. Extremely large furniture pieces, for example, may need extra reinforcement at the joints.
Working With Medium Density Fiberboard (MDF)
MDF is a very dense product that is considerably heavier than plywood or dimension lumber. Keep this in mind when transporting and building with it. Other than this slight drawback, MDF is an excellent building material, as it accepts glue bonds very welland joins securely.It can be cut and shaped with the same tools used for construction and woodworking.
It is best to cut MDF outdoors, as it creates a lot of dust. It is also smart to wear a respirator when cutting or sanding MDF, to avoid exposure to fine dust containing the resins used in its manufacture.When exposed to moisture, unfinished MDF can swell and lose strength, so in applications where frequent moisture exposure is a possibility, exterior-grade plywoods are a better choice.There are, however, special (and more expensive) types of MDF that can be used where moisture is present.
MDF accepts paint best if the surfaces are first primed with an oil-based primer.
Because MDF accepts paint so well, it is often used in visible applications, such as in cabinets, shelves, and furniture pieces that will be painted. Particleboard, on the other hand, does not accept paint very well, and so is more commonly used in hidden locations, such as for underlayment for carpeting or other types of flooring.
What is stronger—MDF, particleboard, or plywood?
For structural purposes, plywood is stronger than the other two products, but MDF is considerably stronger than particleboard. However, MDF is approved for many of the same uses as plywood. A vast number of cabinet and furniture makers, including IKEA, use MDF throughout their products.
Are there toxic chemicals in MDF?
Yes. As is true of most carpeting, plywood, and other sheet goods containing resins, MDF contains VOCs such as urea-formaldehyde. Small amounts of these chemicals may outgas into the environment. You should take precautions while cutting and sanding MDF to avoid inhaling fine dust.
If MDF is medium density fiberboard, are there also low- and high-density fiberboard products?
Yes. The product sold as particleboard is also known as low-density fiberboard. High-density fiberboard (HDF) is more commonly known as hardboard—the thin, sheet product that is often used for pegboard and for thin floor underlayment or as the backing material on shelving units and other furniture. Thicker panels of HDF are sometimes used in high-end furniture.