The edges are scraped and sanded to give as smooth a surface as possible, and the edges are again primed with bole and polished with a burnishing brush. A dilute solution of albumen or gelatin is applied and the gold leaf is laid on. The edges are then glazed with a burnisher, initially through paper and then directly on the edges. Different qualities of paper require slight variations of treatment. In general, the effect of gilt edges is superior if the gilding is done before the book is sewn. See: ROUGH GILT . Following gilding, the edges are sometimes tooled. See: GAUFFERED EDGES .
The gilding of the edges of books probably originated in Italy, at about the same time that gold tooling was introduced in that country, or about 1470. The technique appears to have been in use in England by the 1530s.
Aside from appearance, gilding the edges, or at least the head edge, serves the practical function of protecting the book from the incursion of dust. See also: EDGE GILDING MACHINE ,