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.
