Hardboard is a manufactured wood product used in woodworking and construction. The manufacturing process uses heat and pressure to consolidate wood fibers into sheets. Processing methods for manufacturing hardboard vary.
Hardboard manufacturing begins by softening wood chips in a pressurized steamer and grinding them into fibers. The fibers are mixed with resin, formed into mats and hot pressed to make panels. The panels are heat treated and undergo humidification, a process that adds moisture to prevent warping, before being finished and packaged for shipment.
Woods commonly used for manufacturing hardboard include hardwood and softwood species. The Environmental Protection Agency, or EPA, lists aspen, beech, birch, maple and oak wood chips as common hardwoods. Softwood use is typically limited to pine.
Hardboard is manufactured using one of three processes: wet processing, dry processing or wet/dry processing. Wet processing uses wet wood fibers to form wet mats for pressing. Dry processing uses dry fibers to form dry mats for pressing. Wet/dry processing forms wet mats that are dried before pressing. Unlike wet and dry processing, wet/dry processing does not use resin.