Loose leaves appear earliest in books printed on paper which is so heavy that it breaks almost as soon as it is folded. If the loose leaves of such books are tipped in they tend to tear out with them the ones they are tipped onto. Leaves should rarely be tipped into books which have never been rebound. In rebound books which are in their last days and will never be rebound again it is sometimes proper to tip in.
Full-page illustrations which come loose can in most cases be left out to advantage. To tip them in again hurts the leaves they are fastened to. They are usually so poor that it is a kindness to the reader to throw them away.
In the long run a book needing more than very slight repairs will give better return if so rebound at once that it will hang together until so dirty that it will have to be thrown away.
Some books, especially some of those printed on cheap, heavy, coated paper, will never pay to rebind. They should be mended, each according to its constitution, and when beyond mending thrown away.
Good general rules for mending books are few. The first and most important of all is: Be sparing with paste or other stickist. Another is: If a machine-bound book is broken at the joint, the cover beginning to part from the back, send it straight to the binder.
The best plan is to buy your books as far as possible properly bound for library use direct from the publishers’ sheets. Such books never need mending or rebinding. Being flexible and easily opened their leaves are rarely torn; and, for the same reason, getting no hard pressure from moist or dirty hands in trying to keep them open, their leaves keep clean for a long time.
Books not thus bound in the first place should be rebound in first-class manner when they begin to break. Parsimony in rebinding is a library thief.