In some cases white lead (_ceruse_) was added to the _gesso_, as, for example, in a receipt, given by Cennino Cennini (§ 131 to 139, and 157,) for a mordant made of fine gypsum, ceruse and sugar of Candia, that is ordinary pure white sugar[262]. This is to be ground up with white of egg, applied in thin coats and burnished. To colour the mordant Cennino adds _bole Armeniac_, or _terra verde_, or verdigris green. Giovanni da Modena, a Bolognese illuminator, gives the following receipt for a different gold-mordant to be used with oil instead of albumen or size[263]. Instead of _gesso_ it is to be made of a mixture of white and red lead, red ochre, bole Armeniac and verdigris; the whole is to be ground first with water, then thoroughly dried, and again ground up with a mixture of linseed oil and amber or mastic varnish. This variety of mordant appears to have been used in a good many fifteenth century Italian manuscripts. It is not such a good mixture as the _gesso_ and white of egg, as the oil used to mix with it is liable to stain the vellum through to the other side of the page, and even to print off a mark on the opposite page, especially when the book has been severely pressed by the binder. _Tooled patterns._ _Stamped patterns._ _Tooled patterns on gold leaf._ In many Italian and French manuscripts, especially of the fourteenth and fifteenth centuries, a very rich and brilliant effect is produced with tooled lines impressed into the surface of the flat gold. Diapered and scroll-work backgrounds, the nimbi of Saints, the orphreys and apparels on vestments, and many other kinds of decoration were skilfully executed with a pointed bone or ivory tool, impressed upon the gold leaf after it was burnished, and through the gold into the slightly elastic body of the _gesso-mordant_. Patterns were also produced by the help of minute punches, which stamped dots or circles; these, when grouped together, formed little rosettes or powderings, like those used in the panel paintings of the same time. Gold treated in this way had to be of considerable thickness, and in some cases, when a large flat surface of mordant was to be gilt, as many as three layers of stout gold leaf were employed to give the requisite body of metal. _Silver leaf._ _Burnished silver leaf_ was occasionally used by the mediaeval illuminators, though not very often, as it was very liable to tarnish and blacken. For this reason _leaf tin_ was not unfrequently used instead of silver, as tin does not oxydize in such a conspicuous way; see above, p. 233. The use of all three metals, gold, silver and tin, is described by Theophilus, _Schedula diversarum Artium_, I. 24, 25 and 26. Theophilus speaks of laying the gold leaf directly on to the vellum with the help only of white of egg. This method was not uncommon in early times, and it was not till the end of the thirteenth century that the full splendour of effect was reached by the help of the thick, hard mordant-ground.