The boards for making the covers are cut the required size exactly as when cutting for glueing; a packing of thin cardboard or thin wrappers is cut for the back. The width of the back from first to last sheet is carefully measured by laying across it a strip of paper, the dividers are adjusted to the measure, and this is transferred to the wrapping paper. The packing is cut to suit the boards in height. When cloth only is used for the cover, the cloth is cut 2 to 2-1/2 cm. longer and about 4 cm. wider than the packing. The width of the back depends upon the question of cost or other consideration. In whole-cloth bindings the cloth is, of course, cut in one piece and 1 to 1-1/2 cm. larger all round than the boards and back taken together. Glue is always used for cloth. As piles of pieces of cloth shift about in glueing, a touch of glue is given to two corners of the pile and left to dry a little. These corners hold the pieces of cloth in position whilst being glued and prevent the edges from being smeared. In glueing cloth it must be seen that the glue is well rubbed into the grain or artificial indentations.

For covers which have only the back made, the packing is laid upon the middle of the glued cloth and the boards hinged on right and left at side of it, leaving, however, as much space between as is required by the joint and the thickness of the boards. As a rule, the space required will be as much as the thickness of the board. In making leather backs one allows a little more.

The cloth back is at once turned in at head and tail after the boards have been laid on, and the cover rubbed down in the groove with the folder.

Turning-in is done by pushing the side to be operated on a little over the edge of the table, and with the thumbs the cover is pressed over the edges of the boards with a sliding motion, whilst the forefingers hold the cover underneath.

Whole-cloth bindings are turned in in the same way, but in this case the corners must be first cut off obliquely as shown in the illustration.

Fig. 60—Corners cut for turning in.

The cloth is cut off at the corners so close that only as much as the thickness of the board remains. Thick boards have therefore more cloth left at the corners than thin ones.

Fig. 61—Corners: Right and wrong.

The top and bottom edges must be turned in before the fore-edge. At the corners, the cloth is nipped a little with the folder, without, however, making an oblique fold; there should rather be a hollow round turn-over remaining which is only drawn on with the fore-edge, then from the corner slanting to the board.

The edges must always be turned in quite sharp; there must never be a hollow place on the edge of the board. On the other hand, it looks bad if the edges have been much rubbed down with the folder, at least with cloth; it is different with leather.

The turned-in cover is turned and the front side well rubbed down under paper with the folder. When cloth has once been glued it must not be allowed to lie long as it rolls up and sticks together, which renders it practically unworkable.

The finished covers are laid between pasteboards to dry; only when the drying has to be done in a hurry may they be hung on stretched cords. The latest in this work is a case machine which turns out 550 cases per hour.

When leather is used, it must first be pared, that is to say, the parts to be turned in where it is too thick in the joint must be gradually thinned.

Fig. 62—Paring with Offenbach or Berlin knife.

The paring knife, of which there are various kinds, is used for this work. The best known and the most generally used are the Offenbach and the Berlin, both very much alike except for a slight difference in the edge. The quickest paring knife is made after the French pattern.

This knife is called a "thrusting" knife because of the manner of using it, in contradistinction to those generally used with a cutting motion; but even these a skilful worker will be able to use with a thrusting motion. The under side of the paring knife is covered with leather.

A lithographic stone or piece of marble will serve as a bed upon which to pare the leather. The stone is set in a frame under which there is a bar to hold it against the edge of the table so that it does not work backwards whilst in use. All edges are rounded off and the surface is ground and polished.

Ability in paring does not entirely depend upon the skilful use of the knife but also upon the way the left hand manipulates the leather and upon a thorough knowledge of the nature of the leather. It should not be forgotten that the latter has a grain, though very few bookbinders pay any heed to this. With many leathers it is a very difficult matter to pare against the grain, especially pig-skin and cow-hide. One may generally take it that a leather pares best in the direction in which it stretches least. The grain runs from the back to the sides. The Offenbach knife is narrower and ground more to a square point than the Berlin knife, the edge of which forms a sort of half right-angle to the blade. See manner of holding the knife in Fig. 62.

Quick working is an advantage of the Offenbach knife, which is due to the fact that less attention need be given to holding the leather on the stone, and paring proceeds from left to right, the left hand at the same time helping to push the knife. The Berlin make pares from right to left; here the blade is held almost parallel to the edge of the leather, the point of the knife inclining to the leather; with the other the edge is cut over slantingly with the point outwards.

To use the French knife requires more practice; the cutting edge is almost at right angles to the knife, and, besides, the method of holding it is somewhat unusual. For paring all thick leathers or large surfaces it surpasses all other makes in execution. To make the leather more workable for paring it is previously manipulated, that is to say, it is turned flesh side outwards and rolled to and fro, whilst firm pressure is applied with the second and third fingers of the right hand, thus making it pliable.

Fig. 63—Paring with French knife.

In an ordinary bindery thin or split leathers are mostly used; these do not require very much paring, which is only necessary for pig-skin and the finest moroccos. The latter leather is narrowly pared about 2 to 3 mm. wide along the edge for half as well as for whole bindings. Only the back is pared the whole width, therefore 1 to 1-1/2 cm. has to be nicely gradated. Broken places, inequalities of the edge, or even holes to be filled in, greatly add to the difficulty of the work.

In the thicker skins also—thick places often occur in the otherwise thin skins—the joint must be thinned down. The packing is laid upon the wrong side of the leather and its position marked out with the folder. The leather is pared about 1 cm. in width along this line, that is to say, it is pared so that 1/2 cm. right and left along the mark the thickness of the leather is reduced.

As a rule, first-class books are not provided with a cover made in advance, and even those described by publishers as "super extra" do not rise above morocco goat.

We have to do with the following leathers which are mostly used for the publishers' bindings: Goat-skin (of oriental hybrid sheep), morocco goat, sheep-skin (unsplit sheep-skin), and split sheep-skin [or so-called skivers]. There is another goat-skin, not Levanted, sold and used under the name "bastard" leather. "Levanting" means to imitate by pressing the grain natural to the skins from the Levant. Most kinds of our leather receive their grain by such process.

For whole-leather bindings a narrow margin is pared down all round the edges, the turn-in at the back is pared just as much as is necessary, and also at the corners. The leather corners are cut slant-wise at the outset, and the paring is done so that the thinning begins exactly at the edge of the board.

In leather bindings the board, as well as the back packing, is glued on, rubbed down, and the edges then pasted and turned in, the leather is rubbed down sharply in the joint, the back, and on the edges; but a folder must never be used on the leather covering the board itself.

It frequently happens that the board is finished off with round corners; in this case, the method of turning in cloth as well as leather is slightly different. The two neighbouring edges are turned in. The leather or other material is cut off not quite so close as for square corners, and the material is drawn very smoothly and neatly over the edges in little folds, using a pointed folder for the work.

Books not wholly covered with cloth or leather get corners of the same material as is used for the back. Cloth corners are not cut singly, but a strip of material long enough for the required number of corners is glued and then cut with the shears into pieces of this shape(a) or, better(b), placing them on the boards in such a way that the material projects a little over the corner of the board. First of all, the lappets of the top and bottom edges are turned in, the corners nipped in the manner shown, and then the lappets of the fore-edge are also turned in. Leather corners are treated in the same way, but these are cut from waste pieces according to the zinc stencil plate kept for the purpose, and then pared down.

Glue is used for fixing on cloth corners, but strong paste is always used for leather. All edges and corners are well rubbed down with the folder and left smooth and sharp, but, on the other hand, the grain on the board side must be left uninjured. Insufficient paring of the corners or using only the fingers for turning-in causes very thick edges; such work is out of date and would not be done by any thoughtful workman.

Books bound in half-cloth or half-leather have the sides covered with paper; the latter often with cloth. When cloth sides are used, the material must always harmonize with the back both in regard to colour and texture. On each side to be turned in the paper is cut 1 to 1-1/2 cm. larger than the surface of the board to be covered. The paper is cut along the back with the knife and rule. The corners are turned down in half right-angles according to the size of the cloth or leather corners and somewhat smaller than these, and cut off with the shears as shown in the illustration, using the fold as a guide.

In ordinary work with very small corners, especially in large quantities, the corners may simply be cut off diagonally, and if there are many covers they are knocked up and the cutting is done with knife and rule or with the machine.

As a trade article for the publishers, the finished cover is lined with paper on the inside, both for the sake of improved appearance and to prevent the drawing outwards. For every board a sheet of paper is cut about 1/2 cm. smaller than the board and pasted on. The covers are placed between boards to dry.

Covers are generally decorated in some way; as a rule by means of the blocking press. Where they get any hand tooling, it is always done on the book when bound, for which no case is made in advance. Simple gold lines along the back and corners of the cover are excepted; such work is known as "filleting."