e straight along the joint before
pasting down, it will be well first to fill in with a well pasted and
stretched thin paper, which, if the boards are left open, will draw
them inwards. If the leather joint is pasted down while the board is
curved, the result will be a most unsightly projection on the outside.
When the joint has been cleaned out, and the board made to lie flat,
the leather should be pasted down and mitred. The whole depth of the
turn-in of the covering leather in the joint must not be removed, or
it will be unduly weakened. The mitring line should not come from the
extreme corner, but rather farther down, and there it is well to
leave a certain amount of overlap in the joint, for which purpose the
edge of the turn-in leather and the edge of the leather joint should
be pared thin. After pasting down the leather joints the boards should
be left open till they are dry (see fig. 71). The turn-in and leather
joint are then trimmed out, leaving an even margin of leather all
round the inside of the board, and the panel in the centre filled in
with a piece of thick paper.

[Illustration: FIG. 71.]

When corners and filling in are dry, the boards may be shut up, and
the book is ready for finishing.

It is a common practice to wash up the covers of books that have
become stained with a solution of oxalic acid in water. This is a
dangerous thing to do, and is likely to seriously injure the leather.
Leather, when damp, must not be brought in contact with iron or steel
tools, or it may be badly stained.

CHAPTER XIII

Library Binding--Binding very Thin Books--Scrap-Books--Binding on
Vellum--Books covered with Embroidery

LIBRARY BINDING

_Specifications III and IV_

To produce cheaper bindings, as must be done in the case of large
libraries, some alteration of design is necessary. Appearance must to
some extent be sacrificed to strength and durability, and not, as is
too often the case, strength and durability sacrificed to appearance.
The essentials of any good binding are, that the sections should be
sound in themselves, and that there should be no plates or odd sheets
"pasted on," or anything that would prevent any leaf from opening
right to the back; the sewing must be thoroughly sound; the sewing
materials of good quality; the slips firmly attached to the boards;
and the leather fairly thick