Masonite® board is a composite wood product that is similar to hardboard or fiberboard. It is sold in sheets like plywood or particle board, but is constructed quite differently from these products. This product is made using shredded wood chips, which are heated and mixed to form fine wood fibers. These fibers are then pressed together under high levels of heat and pressure to form a solid sheet of material. Most Masonite® boards contain no glue or adhesives, though some may use resin to enhance strength and durability.
This product was originally introduced by the Masonite® Company, which used these boards to create home siding and a variety of other products. Because Masonite® was one of the first to manufacture this product, the company name has become eponymous for this product, even though the company no longer produces this material. Today, many companies manufacture similar composite wood sheets, but the name "Masonite" is still widely used.
Builders use Masonite® board to level out a floor or countertop before installing finishes such as tile or laminate. Furniture manufacturers may use the product as a base for some low-end furnishings, while many moving companies use these boards to protect the floor and other surfaces when moving heavy objects. These boards are also popular with set designers who use Masonite® board to construct and protect theater and motion picture sets. Because of its smooth surface and light weight, many artists use this board as a cheap alternative to canvas.
There are two basic types of Masonite® board to choose from, including tempered and untempered versions. Untempered board is the standard variety, while tempered board is treated with oil to enhance its moisture resistance. Thickness, size, and finish should also be considered when choosing this type of composite wood product.
Masonite® board offers a number of benefits to users. It is very strong and dense, but is also flexible enough for bending or shaping. Because it is made from pressed fibers instead of glued wood chips like plywood, it holds nails and other fasteners very well. Like other hardboard products, it is cheaper and more lightweight than wood, but is often just as strong. Varieties that are constructed without glue and considered "green" because they do not contribute to indoor air pollution.
When exposed to moisture, Masonite® boards will typically swell or warp. They were once a popular siding material, but after extensive class-action suits in the late 20th century, most Masonite® siding was discontinued. While these boards are similar to fiberboard, they do not posses the same level of structural support, and should not be considered an alternative for most structural applications.