BOOK-BINDING. This interesting art includes not only the fastening together of the leaves of a book ; but also the preliminary operations of folding each sheet so that the several pages of which it consists may follow one another in due order, and of gathering or collecting together in proper sequence the several sheets, and collating or examining them, to see that no error has been made in the arrangement. To aid these operations certain letters or figures, called signatures, are placed at the bottom of the first page and one or two other pages of each sheet.
In the subsequent processes it is necessary to distinguish between the comparatively slight and loose mode of binding in cloth or paper covers, which is technically called board-. ing, and the more solid kind of binding in leather, to which, among the trade, the appli cation of the term binding is limited.
If the book is to be simply boarded, the sewing of the sheets, individually, to a series of strings called bands, stretched in a machine called a sewing-press, is the next operation after folding and collating ; but, if it is to be bound, the sheets are previously either beaten upon a smooth stone, or passed in small par cels through a rolling-press, to make them close and smooth. The bands run across the back of the book, and are often rendered invisible by cutting with a saw, in the back of the collected parcel of sheets, a series of grooves to receive them. After the sheets are thus sewn to the bands, and also con nected together here and there by a ketch stitch, the bands are cut so as to leave about an inch projecting beyond the book on each side, and the back is smeared over with melted glue, which further unites the back edges of the several sheets. The back is then rounded in a curious manner by a process of hammering, before the glue is fully set ; and the book is compressed firmly between two boards, with the back pro jecting a little, while the back is further beaten so as to make it spread out a little over the edges of the boards. If for binding, the edges of the sheets are then ploughed or cut with a machine to a perfectly flat and smooth surface, the convexity of the back being temporarily destroyed while the front edges are cut, so that they may be cut flat, and afterwards re stored, so as to draw them into a correspond ing concavity. If the book is only to be
boarded, it is not usual to cut the top edges, which, being folded, are pretty smooth and regular ; and the front and bottom edges, if cut at all, are only pared sufficiently to remove the principal irregularities.
The boards or pieces of millboard (which is a kind of strong and smooth brown paste board, of different degrees of thickness to suit the different sizes of books), which con stitute what in ordinary language are the covers of the volume, are cut a little larger than the leaves, and, when the volume is to be bound, are laid on the sides of the book, with their back edges against the projecting or overlapping edges of the glued back, and se cured to the book by passing the ends of the strings or bands,which are previously scraped thin, through holes near their back edges, from the outside, and glueing them down firmly and smoothly on the inside. In board ing, however, it is the more usual practice to paste the boards to the paper or cloth cover, leaving a space between their back edges suf ficient for the back of the book, and to con nect the boards with the book simply by past ing down to them the end-papers, or blank leaves which are applied in sewing at the beginning and end of the book. In binding, on the contrary, the leather is put on after the boards are attached to the book in the manner above described. Books are often so boarded or bound as to leave the back of the cover detached from the glued back of the book itself, which is done by interposing a double layer of paper or cloth between the back and the cover, glueing one layer to the cloth or leather cover, and the other to the back, and connecting the two layers with one another at their edges only.