Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

split boards

The boards of a book that are made up of two or more plies of board glued together, except for a distance at the inner edge into which the slips or tapes are glued when the boards are being attached. Generally, if two boards are used they are of different thicknesses, with the thinner of the two adjacent to the text block. If three boards are used, the thinnest is placed in the center and does not extend all the way to the inner edge, thus providing the space for the tapes or slips. In the past some "split boards" were made by splitting a single ply board, either by hand or by machine, thus eliminating the cost of laminating.

The split stopped an inch or so short of the head and tail of the board (in case binding), which made it possible to make the case separately and then attach it to the text block by gluing the tapes into the splits of each board.

Split boards are used today almost exclusively in hand binding and then only for books sewn on tapes, although the technique has also been used occasionally for books sewn on recessed cords. (161 , 236 ,335 )