GILDING
Special manipulation is required for gold leaf applied to the decoration of leather. For gilding over a whole surface, as for instance an aureole round the head of a saint, the following is the best method. Several layers of starch paste are painted with a brush over the part of the leather to be gilded, and followed when dry by a little gelatine paste. A coating of some special preparation is then applied and allowed to dry to the right condition to retain the gold leaf, which varies according to the nature of the preparation; the degree of moisture can be tested with the finger. Gold leaf is sold in small books and is exceedingly thin. A flexible knife, like a palette knife, is used to manipulate it, and a single leaf is laid on a cushion of deerskin stuffed with wadding, and cut to the required size. It is then placed over the preparation on the leather and lightly pressed down with a very soft, round, short-haired brush.
16. Black Morocco binding with applied panels of tooled, cut, painted and gilt calf. Le Roman de Tristan et Iseut. Designed by Robert Engels. Modern French.
For gilding with hot tools a specially prepared powder made of resin or gum is used. This powder melts with the heat of the tool and causes the gold leaf to adhere to the leather only where it comes in contact with the parts of the tool cut in relief. The process is as follows: Some powder is lightly spread over the part of the leather to
be gilded and a piece of gold leaf laid over it, the tool is heated sufficiently to melt the powder without burning the leather and is carefully applied on the right spot, the surplus gold being afterwards removed with the short brush. The tools used by bookbinders are slightly convex, so that firm and even pressure of the whole tool can be exerted by first inclining the handle towards the gilder, and then raising it while still maintaining the pressure and inclining it at the opposite angle.
Gold can also be applied with a brush in the form of powder suspended in liquid gum or spirit varnish. If it does not spread evenly, owing to there being too much liquid in proportion to the powder, dry powder may be added where necessary with a short brush when the liquid is almost dry.
Shell gold is applied with a slightly damped brush and, when dry, may be burnished with an agate or punch; the design of the punch will stand out in bright gold on a ground of dull gold. The pressure of the wrist is sufficient to work the punch and a hammer should not be used.
There is an interesting field for the artist’s enterprise in the discovery of new processes for the decoration of leather by means of colours and bronzes. It is not possible within the limits of a single chapter to give a complete list of the many methods that may be employed.[14]
[14] As a conclusion to this chapter, the French edition quotes from the Bulletin de la Société de l’Encouragement pour l’Industrie Nationale some extracts from the Report of the Committee on Leather for Bookbinding, published by the Society of Arts in London (1901), which will be found in the Note at the end of this volume.