6. Fly Leaves Guarded
Fly-leaves, made of kraft or manila paper running about 60 pounds to the ream, which have previously been guarded with cloth are added to the book. In guarding, a strip of cloth is pasted around the back of the folded fly-leaf covering about one quarter of an inch on each side. When the book is sewed the needle passes through the cloth as well as the paper. Different binders use different materials for guarding fly-leaves, end papers and signatures. It must, however, be a cloth of close weave, strong, and light in weight. The English cloth called jaconet, used by some binders, is probably as satisfactory as any.
This is one part of library binding which differs radically from the custom in ordinary hand work. Old-fashioned binders, unless properly instructed, will simply fold a piece of paper, and tip it on to the first and last signatures with paste, thus forming an element of weakness instead of strength. When the fly-leaves are guarded and properly sewed they become an integral part of the book and no tipping is necessary.
7. Sections Guarded
At this point it is also necessary to guard the first and last signatures of books which are to be sewed in the regular way. Overcast books do not need such guards.
Guarding of first and last signatures is another of the distinctive features of library binding. In the case of books bound in the regular fashion the sewing invariably first gives way at the first and last signatures. Guarding with jaconet prevents the threads which lie in the middle of the signatures from pulling through the paper. This method is essential if it is supposed that the book will be much used. It is not essential for books which will be used only occasionally.
8. Illustrations Guarded
Illustrations are guarded with a thin, tough paper, not with cloth. The guard folds around an adjoining signature and is sewed through.
9. Sawing
If the book is not to be overcast, it is screwed tightly into the backing-press and sawed to make the grooves in which the bands or twines are laid when the book is sewed. Grooves for three bands must be made for books eight inches high, four for twelve-inch books and five for fifteen-inch books. For fiction two bands are used. There must also be two additional grooves, much shallower than the others, about one half inch from the head and tail of the book for the kettlestitch.