BOWED

Bowing is a convex warp or curvature of a book's covers, away from the middle of the text block. Bowed covers occur less often than splayed covers. There are many causes of bowing:

• Stresses in the boards' directional grain can warp them.

• A change in the boards' moisture content can cause their directional grain to warp in one direction.

• Leather, vellum, cloth, or paper covering the boards can shrink more or less than the boards and warp them.

• Pastedowns can shrink more or less than the boards and warp them.