If the book is a valuable one that will receive hard usage and therefore should be as strong as possible, the flesh side of a piece of split goat skin can be used for back-lining, covering the back from joint to joint. It will seldom be necessary, however, to employ this method.
Perhaps nothing better shows the difference between old methods of library binding and new than this one item of back-lining. In the old methods the binders depended for strength largely upon the bands. In the new the bands are practically immaterial when the book is fastened into the cover.
At this point some binders reback to make a sharp joint, and to make the book open more easily. When the canton flannel dries it may pull the back somewhat out of shape. It is doubtful, however, if rebacking is always necessary.
21. Boards Cut
The book is then measured for boards which are cut to the proper size. In measuring it must be remembered that the boards must project an eighth of an inch on all edges (except the back) forming what is called the "squares." It will also make a difference in measuring if the book is to have a French joint. (See page 46.)
22. Cloth Cut
If the book is to be bound in cloth, this is cut the proper size. If leather backs are to be used the covering material consists of two pieces of cloth and one of leather, all of which must be cut to the proper size.
23. Loose Back
If the book is to be made a loose back, a piece of coarse paper is cut the size of the book from joint to joint and the length of the back. This is placed in the book.