Bookboard

Bookboard, in the context of bookbinding, is a thick, rigid paperboard used to form the covers and structural backbone of books, particularly hardcovers and case-bound editions. Sold in large sheets or rolls, it is supplied in several thicknesses and densities and is commonly referred to as greyboard or binder's board in the trade.

Most bookboard is made from recycled fibers or chemical pulps, yielding a dense, stiff material with low porosity. Typical thickness ranges run from about 0.8 mm for lightweight covers to 2–3 mm for sturdy cases, with heavier options used for slipcases and boxes. The surface can be raw greyboard or coated, or finished with a paper, cloth, or leather-like facing.

Uses and processing: It provides the external shell of a hardcover, to which endpapers are glued and over which the cover material is applied. It may also be cut for case inserts, slipcases, or protective enclosures. In production, the board is cut to size, sometimes scored to ease covering, and then adhesively joined to the spine block.

Types and alternatives: The most common form is greyboard, also called binder's board, designed for high stiffness. Lighter alternatives include light-weight board or chipboard used for less demanding bindings. In some contexts, white board or paperboard variants are used for decorative or packaging purposes.

Environmental and sustainability: Recycled content is common, and many suppliers offer boards with recycled fiber and certifications such as FSC. After use, bookboard can be reclaimed through standard paper recycling streams, depending on coatings and adhesives.