Some librarians and binders advocate the use of cloth guards but this seems hardly necessary. The cloth guards tend to swell the back of the book, especially if there be many plates, while the thin, tough paper is strong enough for ordinary books. Folded plates should never be sewed through the middle of the fold, but should be mounted on guards so that the plates will open out nearly flat when the book is opened. Folded maps, or other folded plates which may be consulted often should, unless otherwise specified, be guarded with cloth which is as wide as the book, so that they may be thrown entirely outside the book and lie flat on a table.
18. Illustrations which are folded more than once, such as maps, should be carefully cut and mounted on thin cloth in such a way as to allow for the folding to come on the cloth alone, not on the paper.
19. Stitching (that is, sewing signatures lengthwise with a sewing-machine) or old-fashioned whipstitching, is not permitted for any books; with the possible exception of newspapers.
20. In sewing three bands or tapes must be used for eight-inch books, four for twelve-inch, etc.
21. Tapes, or bands, and back-lining must project at least an inch and a quarter on each side of the book.
22. All books should be lined on the back with canton flannel as described in the chapter on Processes, except in a few cases where it may be advisable to use duck or a flesher. This eliminates lacing-on of boards.
23. Adjoining leaves of fly leaves and end papers must always be pasted together.
24. Books must be trimmed as little as possible.
25. All books should have rounded corners.
26. All books must have French joints.