FIG. 19.—PARING KNIFE
The edges of the leather must now be thinned so that they will more readily stick when turned over and pasted under the board, and also to avoid the unevenness which the normal thickness of the leather would produce underneath. A paring-knife with a broad, flat, very sharp blade (Figs. 18 and 19) is used for this purpose; its manipulation is difficult and requires long practice. The handle is held against the palm of the hand, and the fingers extending over the blade cause it to penetrate the leather superficially by a more or less strong pressure, the object being to take off shavings from the back of the skin, increasing towards the edge until the edge itself is reduced to the thickness of a cigarette paper.
FIG. 20.—PARING LEATHER
The leather is placed surface downwards on a lithographic stone or a slab of marble. It is held stretched with the left hand, the fingers being extended over it on the face of the stone, and the thumb pressed against the side leaving the part just in front of the fingers free to be pared (Fig. 20). It is of the first importance for the success of this operation that the leather should be kept well stretched. The knife is held almost horizontally to avoid cutting into the leather at too sharp an angle, and is worked from left to right towards the edge.
The leather is then fastened to the cardboard by pasting either the whole of it or only the edges, which are turned underneath. In any case ordinary paste should be used; seccotine or glue would sink into and harden the leather, making the subsequent outlining process difficult.
When the piece of leather is so large that it would cause the board to warp when it dries, some paper should be pasted on the other side of the board, which will keep it flat by drawing it in the opposite direction.