Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

backing

The process of shaping a ridge or shoulder on each side of the spine of a text block prior to the application of the spine lining material. The backs of the sewn sections or leaves are bent over from the center to the left and right until shoulders are formed against which the boards will fit. The dimension of the shoulders is determined by the thickness of the boards to be used, which, in turn, is determined by the size and bulk of the book. In addition to providing for the boards, backing also:1) allows for the swell of the spine caused by the thread used in sewing, or by excessive guarding; 2) helps maintain the round of the book by the fact that each leaf from the center outward is folded over the leaf next to it so that it cannot work its way forward and thus cause the book to cave in (See: START ); 3) helps impart more flexibility to the book by creating a slight crease in each leaf near the spine, to the extent that backing has something of a scoring effect which makes the book easier to open and facilitates turning the leaves (See: SCORE ); and 4) makes a better joint for the cover, one which opens easier and is stronger, since the point of strain during opening is spread over a strip of the covering material, e.g., a FRENCH JOINT .

Furthermore, the angle of conformation of the spine caused by backing probably provides for better vertical standing support of the text block.

Backing may be accomplished by hand with the use of a BACKING HAMMER or, in the case of edition and library binding, by means of a ROUNDING AND BACKING MACHINE . In some cases e.g., very large books, backing may be done in a BACKER as a separate operation.

Some authorities consider the backing of a book to be the most important and difficult of all the processes in the craft of hand bookbinding, and poor or inadequate backing is certainly one of the major sources of problems in the processes of edition and library bookbinding.

Although books dating from at least as early as the beginning of the second half of the 15th century were often rounded, backing for the purpose of forming shoulders seems not to have been an established procedure before 1500, or perhaps somewhat later. It is uncertain when bookbinders discovered that rounding and backing was a superior bookbinding technique. The swell caused by sewing sometimes causes books to assume a slight round with no effort on the part of the bookbinder, and, over a long period of time, the pressure of the boards perhaps even results in the effect of backing. (209 , 236 , 335 , 339 )