When the slips have been pasted and the squares set, tins can be put inside and outside the boards, and the book given a slight nip in the press to flatten the slips. Only a comparatively light pressure should be given, or the lining up of the headbands or back will become cockled and detached.
PARING LEATHER
While the slips are being set in the press the cover can be got out. Judgment is necessary in cutting out covers. One workman will be able, by careful cutting, to get six covers out of a skin where another will only get four. The firm part of the skin is the back and sides, and this only should be used for the best books. The fleshy parts on the flanks and belly will not wear sufficiently well to be suitable for good bookbinding.
The skin should be cut out leaving about an inch all round for turning in when the book is covered, and when cut out it must be pared. If the leather is of European manufacture most of the paring will have been done before it is sold, and the leather manufacturer will have shaved it to any thickness required. This is a convenience that is partly responsible for the unduly thin leather that is commonly used. The better plan is to get the leather rather thick, and for the binder to pare it down where necessary. For small books it is essential, in order that the covers may open freely, and the boards not look clumsy, that the leather should be very thin at the joint and round the edges of the boards. For such books it is very important that a small, naturally thin skin should be used that will not have to be unduly pared down, and that the large and thicker skins should be kept for large books.
Binders like using large skins because there is much less waste, but if these skins are used for small books, so much of the leather substance has to be pared away, that only the comparatively brittle grained surface remains. By the modern process of dyeing this surface is often to some extent injured, and its strength sometimes totally destroyed.
When the cover has been cut to size the book is laid on it with the boards open, and a pencil line drawn round them, a mark being made to show where the back comes. The skin is then pared, making it thin where the edge of the boards will come. Great care must be taken that the thinning does not commence too abruptly, or a ridge will be apparent when the leather is on the book.
The paring must be done quite smoothly and evenly. Every unevenness shows when the cover is polished and pressed. Care is needed in estimating the amount that will have to be pared off that part of the leather that covers the back and joints. The object of the binder should be to leave these portions as thick as he can consistently with the free opening of the boards. The leather at the head-caps must be pared quite thin, as the double thickness on the top of the headband is apt to make this part project above the edges of the board. This is a great trouble, especially at the tail, where, if the head-cap projects beyond the boards, the whole weight of the book rests on it, and it is certain to be rubbed off when the book is put on the shelf.
Fig. 59.