Fig. 69.
Fig. 70.
The next operation will be to fill in the board and mitre the corners. To fill in the boards, a piece of paper as thick as the turn-in of the leather (engineer’s cartridge paper answers very well) should be cut a little smaller than the board, with one edge cut straight; then with the straight edge adjusted to the back of the board, and a weight placed on the centre, the paper is marked round with dividers set to the intended width of the turn-in of the leather. Then with a sharp knife, paper and leather may be cut through together. The paper should then be marked to show its position on the board, and the ragged edges of the leather trimmed off. This will leave an even margin of leather on three sides of the inside of the board, and a piece of paper that will exactly fit the remaining space. The corners must next be mitred. To do this, both thicknesses of leather are cut through from the corner of the board to the corner of the inside margin. The knife should be held slightly slanting to make a cut, as shown at [fig. 70]. The corners should then be thoroughly damped, and the overlapping leather from both sides removed, leaving what should be a neat and straight join. If the leather at the extreme corner should prove to be, as is often the case, too thick to turn in neatly, the corners should be opened out and the leather pared against the thumb nail, and then well pasted and turned back again. The extreme corner may be slightly tapped on the stone with a hammer, and the sides rubbed with a folder, to ensure squareness and sharpness. When all four corners have been mitred, the filling in papers can be pasted in. As they will probably stretch a little with the paste, it will be well to cut off a slight shaving, and they should then fit exactly. When the boards have been filled in and well rubbed down, the book should be left for some hours with the boards standing open to enable the filling-in papers to draw the boards slightly inwards to overcome the pull of the leather.
In cases where there are leather joints the operation is as follows: The waste end paper is removed, and the edge of the board and joint carefully cleaned from glue and all irregularities, and if, as is most likely, it is curved from the pull of the leather, the board must be tapped or ironed down until it is perfectly straight. If there is difficulty in making the board lie straight along the joint before pasting down, it will be well first to fill in with a well pasted and stretched thin paper, which, if the boards are left open, will draw them inwards. If the leather joint is pasted down while the board is curved, the result will be a most unsightly projection on the outside. When the joint has been cleaned out, and the board made to lie flat, the leather should be pasted down and mitred. The whole depth of the turn-in of the covering leather in the joint must not be removed, or it will be unduly weakened. The mitring line should not come from the extreme corner, but rather farther down, and there it is well to leave a certain amount of overlap in the joint, for which purpose the edge of the turn-in leather and the edge of the leather joint should be pared thin. After pasting down the leather joints the boards should be left open till they are dry (see [fig. 71]). The turn-in and leather joint are then trimmed out, leaving an even margin of leather all round the inside of the board, and the panel in the centre filled in with a piece of thick paper.
Fig. 71.
When corners and filling in are dry, the boards may be shut up, and the book is ready for finishing.