Page:The Art of Bookbinding, Zaehnsdorf, 1890.djvu/48

18 book is separated into divisions or sections of four, six, or eight leaves, according to the thickness of the paper, and each section is then overcast or over sewn along its whole length, the thread being fastened at the head and tail (or top and bottom); thus each section is made independent of its neighbour. The sections should then be gently struck along the back edge with a hammer against a knocking-down iron, so as to imbed the thread into the paper, or the back will be too thick. The thread should not be struck so hard as to cut the paper, or break the thread, but very gently. Two or three sections may be taken at a time.

After having placed the plates, the book should be put into the press (standing or otherwise) for a few hours. A standing press is used in all good bookbinding shops. The Paris houses have a curious way of pressing their books. The books are placed in the standing press; the top and bottom boards are very thick, having a groove cut in them in which a strong thin rope is placed. The press is screwed down tightly, when, after some few minutes has elapsed, the cord or rope is drawn together and fastened. The pressure of the screw is released, the whole taken out en bloc, and allowed to remain for some hours, during which time a number of other batches are passed through the same press.

When taken out of the press the book is ready for "marking up" if for flexible sewing, or for being sawn in if for ordinary work.

Interleaving.—It is sometimes required to place a piece of writing paper between each leaf of letter-press, either for notes or for a translation: in such a case, the book must be properly beaten or rolled, and each leaf cut up with a hand-knife, both head and foredge; the writing paper having been chosen, must be folded to the size of the book and pressed. A single leaf of writing paper is now to be fastened in the centre of each section, and a folded leaf