Among the various techniques used for the gilding of a surface, bole gilding is definitely the most common and appreciated. The method is amply described by Cennino Cennini (end of the 14th century) and essentially consists of applying one or more layers of Armenian bole, dissolved with animal glue, onto a previously gessoed and smooth surface. Smoothing the surface again, a thin layer of warm glue diluted in water is applied to small portions of the surface. This is followed by the application of gold leaf, making sure that it adheres perfectly to the surface. The gilded surface is then burnished and eventually decorated with engravings or punch marks.