Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

corner mitering

The process or operation of accurately joining the edges of the covering material of a book that has been turned-in at the edges of the board. The purpose is to have a minimum of overlapping of cloth, or a pared overlapping of leather or vellum.

Corner mitering has been altered considerably down through the history of bookbinding. One particular method, which was used well into the 16th century, involved cutting the leather so as to leave a tongue, with the cut- ting usually being done after the leather had been turned-in. In other methods, the leather was turned-in and then cut so that the vertical edges of the leather butted, or nearly so. An opposite technique was to cut the leather before turning it in, with the result that it overlapped a great deal more than is usual today, and left a small gap at the corners. This technique appears to have been in general use from the second half of the 16th century to the end of the 18th or early years of the 19th. Toward the end of this period the leather was pared thinner and the gap at the corner was considerably neater. During the last three-quarters of the 19th century the most common method of corner mitering of full leather bindings was to pare them diagonally and on a bevel before turning-in, so that the two edges overlapped to the extent of the bevel, coming together at an angle of 45° from the corner. (236 )