Medium-density fibreboard

A sample of MDF

MDF output in 2005

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. MDF is denser than plywood. It is made up of separated fibres, but can be used as a building material similar in application to plywood. It is stronger and much more dense than normal particle board.

The name derives from the distinction in densities of fibreboard. Large-scale production of MDF began in the 1980s.^{[citation needed]}

Physical properties

The word, MDF, over the period of time has become a generic name for any dry process fiber board. The range of Density and classification as Light or standard or High density board is a misnomer and confusing. Density of Board when evaluated in relation to density of the fiber that goes in to making of the Panel is important. A thick MDF Panel at 700-720 density in case of Softwood Fiber Panels may be considered as high density whereas a Panel of same density when made of Hard Wood Fibers is not so.

With the experiences gained over the period of time, the industry has evolved MDF as an application driven product suitable to specific applications.

Comparison to natural woods

MDF does not contain knots or rings, making it more uniform than natural woods during cutting and in service. However, MDF is not entirely isotropic, since the fibres are pressed tight together through the sheet. Like natural wood, MDF may split when woodscrews are installed without pilot holes, and MDF may be glued, doweled or laminated, but smooth-shank nails do not hold well. Typical fasteners are T-nuts and pan-head machine screws.

Safety aspects - "probable human carcinogen"

When MDF is cut a large quantity of dust particles are released into the air. It is important that a respirator be worn and the material 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 all sides of the finished piece 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 constant 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" associated with nasal sinus cancer and nasopharyngeal cancer, and possibly with leukaemia in June 2004.

References

Reference Sources

• Jesberger, Lee FX-Platform
• HCHO_Certificate Norboard
• Lignocellulosic Composites
• Design-Technology.Org
• Spence, William P. (2005). The Home Carpenters & Woodworker's Repair Manual. New York: Sterling. ISBN 1-4027-1055-0

External links

• Pro Woodworking Tips.com
• A video podcast from podcastschool.net
• Wood Dust - dangers of exposure to wood dust, including MDF dust (from the Worker's Health Centre)
• Formaldehyde An Introduction to Indoor Air Quality: Formaldehyde
• The Medium Density Fiberboard Home Page (although not updated or maintained, still a valuable reference)