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.

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 turnover 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.

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 b9 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 cowhide. One may generally take it that 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.

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