As soon as the varnish is dry the boards may be pressed, one at a time, to give the leather a smooth surface (see [fig. 83]), leaving each board in the press for some hours.
Fig. 89.
After each board has been pressed separately the book should be shut, and pressed again with pressing plates on each side of it, and with tins covered with paper placed inside each board. Light pressure should be given to books with tight backs, or the leather may become detached.
If, on removing from the press, the boards will not keep shut, the book should be pressed again with a folded sheet of blotting-paper in each end. The blotting-paper should have the folded edge turned up, and be placed so that this turned-up edge will be in the joint behind the back edge of the board when the book is shut.
A small nipping-press suitable for giving comparatively light pressure, is shown at [fig. 89].
TOOLING ON VELLUM
Most covering vellum has a sticky surface, that marks if it is handled. This should be washed off with clean water before tooling. The pattern is blinded in through the paper as for leather, excepting that the paper must not be pasted directly to the vellum, but may be held with a band going right round the board or book. It is best to glaire twice, and to lay on a small portion of gold at a time with benzine. As vellum burns very readily, the tools must not be too hot, and some skill is needed to prevent them from slipping on the hard surface.
Vellum must not be polished or varnished.