Hardboard (or high density fiberboard) is reconstructed, recycled wood. It is made from wood fibres that are glued with resin and other binders and pressed under high pressure and temperature. Hardboard has a variety of applications and advantages and is a popular construction material.
Hardboard is made of pulped wood chips, which are combined with wax and resin adhesives (phenol formaldehyde) to improve the strength and water resistance of the finished hardboard. After the addition of water or air, the pulp is flattened into a mat and prepressed. The final stage involves hot-pressing the flattened pulp under high temperatures (between 87.7 and 115 degrees C) and pressures. The finished product is left to dry and then cut to shape. In the wet process of hardboard manufacture, water is added to the pulp, while dry process hardboard uses air as a forming medium. Hardboard is additionally tempered to improve its moisture-resisting properties. This is done by soaking finished hardboard panels in oils and then baking them at high temperatures.
According to "Building Materials," hardboard is classified into three basic types: oil-tempered, medium and standard. Oil tempered hardboards are infused with oil to make them better resistant to moisture and scratches. Oil tempered hardboards are harder and stiffer than medium and standard hardboards. Medium hardboard has a density between 480 to 800 kilograms per cubic meters. Normal hardboard is denser than medium hardboard (density lies between 800 and 1200 kilograms per cubic meters). Medium and standard hardboards are available in thicknesses of 6 millimetres, 8 millimetres, 10 millimetres and 12 millimetres.
Hardboard is used in the construction industry (to make wall panels, wall sheathing, wall claddings, roof and floor underlying, display panels, wall linings and structural bracing), the auto industry (dashboards, door panels, roof panels, back window decks and caravan interiors) and to make furniture (room dividers, exteriors for cupboards and cases, drawers, desktops, dust stops, doors, cabinet tops and bed headboards).
Hardboard is easy to work with, consistent (minor surface defects), cheaper than solid wood products, and is available in a wide range of styles and textures. Hardboard has the look, insulating qualities and strength of natural wood and is resistant to impact and shock. You can also mould hardboard into various shapes.
Hardboard has poor moisture resisting properties and is not suitable for outdoor use. According to "Exterior Walls," hardboard requires careful painting, caulking and fastening, and long lengths of the board are susceptible to bending and breaking due to expansion. Hardboard furniture and construction components need periodic inspection and maintenance.