Medium-density fibreboard is made up of particles of softwood bonded together with UF adhesive. The mix of wood particles and adhesive are formed into panels by heating and pressing in steel molds, which produces a smooth surface finish. Fire retardant MDF grades are typically red, and moisture resistant grades are green.
Medium-density fiberboard (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.
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.
Types of MDF
There are different kinds of MDF, which are sometimes labeled by colour:
Moisture resistant is typically green
Fire retardant MDF is typically red or pink
Although similar manufacturing processes are used in making all types of fiberboard, MDF has a typical density of 600-800 kg/m³ or .022-.029 lbs/in3, in contrast to particle board (160-450 kg/m³) and to high-density fiberboard (600-1450 kg/m³).
Another addition to the MDF range is a product named FX-Platform, produced by Norbord. It is a softwood plywood core, laminated on both sides with MDF, giving it working properties containing the advantages of both plywood and MDF. This product has met the acceptance criteria for compliance with the ANSI/HPVA HP-1-2004 Section 3.12 Formaldehyde Emission Requirements for industrial panels.
Lighter densities of fiberboard are commonly marketed as ultralight or LDF boards.
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 (no grain), so no tendency to split
Consistent in strength and size
Flexible. Can be used for curved walls or surfaces.
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.