The cover should be very carefully washed with a soft sponge and clean water, to clean off any dirt or finger-marks, and to make the book look as fresh as possible. This washing must be very carefully done by going over the surface as few times as possible. This caution applies particularly to the prepared or artist vellum, as each washing will take off a certain amount of the surface, so that the more it is damped and rubbed the more the surface will be disturbed and the beauty destroyed. It requires some experience to distinguish the flesh and leather surfaces of prepared vellum, but this experience must be acquired, because it is absolutely necessary that the leather side should be outward when the book is covered, for two reasons: the flesh side is more fibrous, and adheres better to the boards than the leather side, and the leather side is less liable to have its surface disturbed in the process of washing.
The parts that are to be gilt must be glaired, but as the glaire will show its presence, or, more strictly speaking, leave rather a dirty mark, the tools should first be worked in blind, and the glaire laid on carefully up to their outer edge. When dry, lay the gold on and work the tool in. Let the tools be only moderately warm: if too hot they will go through to the mill-board, leaving their mark as if they had been cut out with a knife.
As a rule no very heavy tooling is ever put on vellum, the beauty lies in keeping the vellum as clean as possible. The tooling being, comparatively speaking, on the surface, owing to the thinness of the skin, requires a very competent and clean workman to produce anything like good work on vellum.
Vellum is of so greasy a nature that, if a title-piece of leather has to be put on, it will be found that there is a great difficulty in making it adhere properly unless some special precaution be taken. The best plan is to scrape