A high-density fiberboard building material first made by Masonite Corporation in 1926. Hardboard is composed of 100% wood fibers obtained from wood chips, sawdust, and board trimmings. They are broken into fine particles by grinding (dry process) or by steam (wet process). The interfelted fibers are consolidated with heat and pressure (at least 31 pounds per cubic foot) to form a dense, rigid sheet that is held together by naturally occurring lignin with no additional adhesive. Hardboards range from a dark brown to a light tan in color and have one very smooth surface; the reverse side has a wire screen impression. Some hardboards contain a small amount of oil on the surface either as a residual lubricant or as an additive to increase weather resistance (such as Tempered Presdwood). These oils may hinder the adherence of paint or gesso and may be removed with acetone.
Synonyms and Related Terms
fiberboard; aglomerado de fibras duro (Port.); Masonite [IPI]; Presdwood [IPI]; Medex; Medite; Duron [IPI]; Upson; Homasote; Insulite
Hazards and Safety
Any wood product may release organic acids with time.
A.Katlan, "Early Wood-Fiber Panels: Masonite, Hardboard and Lower-Density Boards" JAIC 33:301-306, 1994.
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