The first mass-produced medium-density fiberboards or MDF were introduced in the United States in 1966. Norbord, previously known as Northwood Panelboard, is often credited with producing this engineered wood in its U.S. factory.
Note that the development of this product is part of the long history of finding uses for the significant amounts of wood chips and shavings discarded by lumber mills and to find inexpensive alternatives to solid wood and plywood. These began in the twentieth century. Nevertheless, in the 1970s, production expanded in Europe and it further saw large-scale production and widespread adoption beginning in the 1980s.
Manufacturing technology for MDF continuously improved. This included advancements in fiber processing, the development of better resins, and improved pressing techniques. Production and use spread further across the globe.
Canada has become one of the main producers. China also started producing medium-density fiberboard products in the early 1990s. Production facilities also appeared in other Asian countries and Latin America. Specific variants like moisture-resistant and fire-retardant MDFs have also been introduced in the global market. MDF as a whole has now become a common material used in construction and furniture making.
Understanding Medium-Density Fiberboards
Advantages of Medium-Density Fiberboards and Notable Applications
MDFs or medium-density fiberboards are engineered wood products made by breaking down hardwood or softwood residuals into wood fibers, combining them with wax and a resin binder, and forming panels or boards by applying high temperature and pressure. The following are their advantages and applications:
1. Smooth and Uniform Surface
One of the main advantages of medium-density fiberboards is their smooth surface. They do not have knots and grains. This makes them an excellent base for painting, veneering, and laminating and further allows for a flawless finish that mimics natural or solid wood.
The aforesaid advantage also translates to more aesthetically pleasing finished products. Using them can also reduce processing time and labor costs. Paint adheres evenly. Both veneers and laminates adhere well. Moreover, compared to natural wood, less sanding is required.
2. Relatively Consistent and Stable
Natural wood has knots and variations in density and grain patterns. MDFs have a consistent fiber distribution. This eliminates weak spots and unpredictable behavior that are often seen in natural wood. Machining like cutting and drilling often produce predictable results.
It is also important to underscore that medium-density fiberboards do not expand nor contract as much as natural wood with changes in temperature and humidity or moisture level. This reduces warping and ensures consistent fit and appearance in furniture or built-ins.
3. Uncomplicated and Adaptable
Another advantage of medium-density fiberboards is that they are easy to work with. They can be cut, drilled, and shaped without splintering or chipping. This makes them ideal for intricate designs and customized applications. They are even easier to machine than plywood.
It is worth mentioning that the production of MDFs is a controlled process. This results in products with consistent and accurate dimensions from one sheet to the next. This is important for applications in which precise dimensions for accurate fitting and cuts are required.
4. Cost-Effective Wood Materials
A trip to suppliers or distributors would reveal that medium-density fiberboards are cheaper than solid wood and plywood. For example, a four-by-eight feet and three-fourth-inch MDF panel costs around USD 30 to 50 while plywood with similar dimensions costs USD 45 to 70.
The lower cost of MDFs comes from the fact that they are manufactured using wood residuals from lumber processing. These products also do not depend on high-quality timber logs that are required for solid wood lumber. Manufacturing process has also improved over the decades.
5. Widespread Applications
MDFs are common in modern constructions or as components of modular homes and prefabricated homes. These materials are also used in modular fixtures and ready-to-assemble furniture. MDFs have better acoustic or sound-absorbing properties than plywood and solid wood.
The development of variants with special properties expands further their applications. There are variants that are moisture-resistant and fire-retardant. MDFs can also be treated with chemicals to make them resistant to termites or molds during the manufacturing process.
Disadvantages of Medium-Density Fiberboards and Key Limitations
The advantages of medium-density fiberboards listed and described above make them a better option over solid or natural wood and plywood in certain applications. However, in terms of value and appeal, solid wood is considered the most premium choice. Plywood is also stronger. Below are their disadvantages and limitations:
1. Lower Structural Strength
One of the main disadvantages of medium-density fiberboards, especially when compared to solid wood and even plywood, is its lower structural strength. MDFs have bending strength or modulus of rupture of 16 to 40 MPa and stiffness or modulus of elasticity of 2.5-3.0 GPa.
High-quality solid wood from certain wood species has a bending strength of around 100 MPa and stiffness of around 12 GPa. The same is true for premium plywood from certain species that can have a bending strength of around 40-70 MPa and stiffness of between 7-10 GPa.
2. High Water Absorption
It is important to highlight the fact that MDFs have high water absorption despite some resistance to ambient moisture. Standard MDFs or those with no moisture resistance can absorb up to 80 percent of their weight in water. These materials can swell and break over time.
There are variants that provide some level of moisture resistance through chemical treatment during the manufacturing process. Standard MDFs can be made somewhat resistant to water through sealing on all sides and edges and with the application of a waterproof finish.
3. Poor Fastener Holding
Nails and fine-pitch screws do not hold well in the edge of MDF and can cause splitting unless pilot holes are drilled. Special coarse-threaded screws or sheet metal screws are recommended for edge fastening. Screws can strip easily if over-tightened or removed and reused.
Structures built with MDF and relying on edge fasteners will have a lower load-bearing capacity compared to those made with materials with better edge holding. Designs that depend on simple butt joints secured with edge screws might not be feasible when using MDF.
4. Health and Hazard Concerns
Another disadvantage of medium-density fiberboards is that most can release formaldehyde since these materials often use urea-formaldehyde resin. Formaldehyde is classified as a probable human carcinogen by the EPA. Low-emission MDFs are available but are costlier.
Machining MDFs also produce fine dust and release formaldehyde. Adequate ventilation and respiratory protection are necessary when working with these materials. MDFs are also difficult to recycle or upcycle and are often incarcerated or sent to landfills at the end of their life.
5. Limitations in Applications
The low structural strength of medium-density fibers means that they are not ideal for load-bearing applications and heavy-use furniture. Their high water absorption or moisture retention indicates further that these materials are not suitable for bathrooms, kitchens, and outdoor use.
Moreover, because of their poor fastener holding or poor screw holding capacity, structures and furniture held or fastened on the edge are weaker. MDFs are not ideal for applications where joints will be subjected to significant pulling forces or repeated stress on the edges.
Choosing Medium-Density Fiberboards
The advantages of medium-density fiberboards make them ideal for cost-effective construction or design undertakings that require efficient machining and smooth surfaces. This is the reason why these materials are commonly used in wall partitions, modular cabinets, and low-cost furniture. However, in applications where structural strength or moisture resistance is important, MDFs are not recommended. It also cannot compete against the natural appeal of solid wood.