Fig. 39.
To back the book, backing boards are placed on each side (leaving the slips outside) a short distance below the edge of the back ([fig. 39]). The amount to leave here must be decided by the thickness of the boards to be used. When the backing boards are in position, the book and boards must be carefully lowered into the lying press and screwed up very tight, great care being taken to see that the boards do not slip, and that the book is put in evenly. Even the most experienced forwarder will sometimes have to take a book out of the press two or three times before he gets it in quite evenly and without allowing the boards to slip. Unless the back has a perfectly even curve when put in the press for backing, no amount of subsequent hammering will put it permanently right.
Fig. 40.
Fig. 41.
The backs of the sections should be evenly fanned out one over the other from the centre outwards on both sides. This is done by side strokes of the hammer, in fact by a sort of “riveting” blow, and not by a directly crushing blow (see [fig. 41], in which the arrows show the direction of the hammer strokes). If the sections are not evenly fanned out from the centre, but are either zigzagged by being crushed by direct blows of the hammer, as shown in [fig. 42], A, or are unevenly fanned over more to one side than the other, as shown in [fig. 42], B, the back, although it may be even enough when first done, will probably become uneven with use. A book in which the sections have been crushed down, as at [fig. 42], A, will be disfigured inside by creases in the paper.