Fraying out Slips — Glueing up — Rounding and Backing
After sewing, the book should be looked through to see that all sheets and plates have been caught by the thread, and special attention should be given to end papers to see that the sewing lies evenly.
The ends of the cords should next be cut off to within about two inches of the book on each side, and the free portions frayed out. If proper sewing cord is used, this will be found to be very easily done, if a binder’s bodkin is first inserted between the two strands, separating them, and then again in the centre of each separated strand to still further straighten the fibres (see Fig. 34).
The fraying out of the thick cord recommended for heavy books is a more difficult operation, but with a little trouble the fibres of any good cord can be frayed out. Vellum or tape bands will only require cutting off, leaving about two inches free on each side. The free parts of the bands are called slips.
The book is now ready for glueing up. A piece of waste mill-board or an old cloth cover is put on each side over the slips, and the book knocked up squarely at the back and head. Then it is lowered into the lying press and screwed up, leaving the back with the protecting boards projecting about three-quarters of an inch. If the back has too much swelling in it or is spongy, it is better to leave the slips on one side free and to pull them as tight as possible while the book is held in the press, or a knocking-down iron may be placed on one side of the projecting back and the other side tapped with the backing hammer to make the sections lie close to one another, and then the slips pulled straight (Fig. 35). The back must now be glued. The glue for this operation must be hot, and not too thick. It is very important that it should be worked well between the sections with the brush, and it is well after it has been applied to rub the back with a finger or folder to make quite sure that the glue goes between every section for its entire length. If the book is too tightly screwed up in the press, the glue is apt to remain too much on the surface; and if not tightly enough, it may penetrate too deeply between the sections. If the glue is thick, or stringy, it may be diluted with hot water and the glue-brush rapidly spun round in the glue-pot to break it up and to make it work freely.
Very great care is needed to see that the head of a previously trimmed book is knocked up exactly square before the back is glued, for if it is not, it will be very difficult to get it even afterwards.
The amount of rounding on the back of a book should be determined by the necessities of the case; that is to say, a back that has, through guarding, or excess of sewing, a tendency to be round, is best not forced to be flat, and a back that would naturally be flat, is best not forced to be unduly round. A very round back is objectionable where it can be avoided, because it takes up so much of the back margins of the sheets, and is apt to make the book stiff in opening. On the other hand, a back that is quite flat has to be lined up stiffly, or it may become concave with use.
The method of rounding is to place the book with the back projecting a little over the edge of the press or table, then to draw the back over towards the workman, and, while in this position, to tap it carefully with a hammer (see Fig. 36). This is repeated on the other side of the book, and, if properly done, will give the back an even, convex form that should be in section, a portion of a circle. Rounding and backing are best done after the glue has ceased to be tacky, but before it has set hard.
Backing is perhaps the most difficult and important operation in forwarding. The sewing threads in the back cause that part to be thicker than the rest of the book. Thus in a book with twenty sections there will be in the back, in addition to the thickness of the paper, twenty thicknesses of thread.
If the boards were laced on to the book without rounding or backing, and the book were pressed, the additional thickness of the back, having to go somewhere, would cause it to go either convex or concave, or else perhaps to crease up (see Fig. 37). The object of rounding is to control the distribution of this swelling, and to make the back take an even and permanently convex form.
If the boards were merely laced on after rounding, there would be a gap between the square ends of the board and the edge of the back (see Fig. 38), though the convexity and even curve of the back would be to some extent assured. What is done in backing is to make a groove, into which the edges of the board will fit neatly, and to hammer the backs of the sections over one another from the centre outwards on both sides to form the “groove,” to ensure that the back shall return to the same form after the book has been opened.
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.
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.
It is a mistake to suppose that a very heavy hammer is necessary for backing any but the largest books. For flexible books a hammer with a comparatively small face should be used, as by its use the book can be backed without flattening the bands. It is well to have a hammer head of the shape shown in Fig. 43. By using the thin end, the force of a comparatively light blow, because concentrated on a small surface, is effective.
At Fig. 44 is shown an ordinary backing hammer.
Last updated Monday, December 22, 2014 at 10:48