MDF

Medium-density fibreboard (MDF) is an engineered wood product formed by breaking down hardwood or softwood residuals into wood fibres, often in a defibrator, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure.[1] MDF is denser than plywood.

It is made up of separated fibers, (not wood veneers) but can be used as a building material similar in application to plywood. It is much more dense than normal particle board.

The name derives from the distinction in densities of fiberboard. Large-scale production of MDF began in the 1980s

MDF is often used in school projects because of its flexibility. It is also often used in loudspeaker enclosures, due to its increased weight and rigidity over normal plywood.

Safety aspects of MDF

When MDF is cut, a large quantity of dust particles is released into the air. It is important that a respirator be worn and the wood be cut in a controlled and ventilated environment. It is a good practice to seal the exposed edges to limit the emissions from the binders contained in this material.

Formaldehyde resins are commonly used to bind MDF together, and testing has consistently revealed that MDF products emit urea formaldehyde and other volatile organic compounds that pose health risks at sufficient concentrations, for at least several months after manufacture. Urea formaldehyde is always being slowly released from the surface of MDF. When painting it is good idea to coat the whole of the product in order to seal in the urea formaldehyde. Wax and oil finishes may be used as finishes but they are less effective at sealing in the urea formaldehyde.

Whether these chronic emissions of formaldehyde reach harmful levels in real-world environments is not yet fully determined. The primary concern is for the industries using formaldehyde. As far back as 1987 the U.S. EPA classified it as a probable human carcinogen and after more studies the WHO International Agency for Research on Cancer (IARC), in 1995, also classified it as a probable human carcinogen. Further information and evaluation of all known data led the IARC to reclassify formaldehyde as a known human carcinogen [6] associated with nasal sinus cancer and nasopharyngeal cancer, and possibly with leukemia in June 2004

Benefits of MDF:

• Is an excellent substrate for veneers.
• Is becoming an environmentally friendly product.
• Some varieties are less expensive than many natural woods
• Isotropic (its properties are the same in all directions as a result of no grain), so no tendency to split
• Consistent in strength and size
• Flexible. Can be used for curved walls or surfaces.
• Shapes well.

Drawbacks of MDF:

• Denser than plywood or chipboard (the resins are heavy)
• Swells and breaks when waterlogged
• May warp or expand if not sealed
• Contains urea-formaldehyde which may cause eye and lung irritation when cutting and sanding
• Dulls blades more quickly than many woods
• Though it does not have a grain in the plane of the board, it does have one into the board. Screwing into the edge of a board will generally cause it to split in a fashion similar to delaminating.
• Subject to significant shrinkage in low humidity environments.
• Trim (i.e. baseboards) comes pre-primed but this is insufficient for fine finish painting. Painting with latex paints is difficult due to rapid water absorption. Most finishes appear uneven and nail holes tend to pucker a bit.