The art of gilding antique frames is a meticulous and intricate process that requires precision, patience, and a range of specific materials and tools. Firstly, it is necessary to employ materials and procedures as faithful as possible to those used in the original creation. Regarding materials, for example, one must identify the shade and thickness of the gold leaf used in the original artifact or, in any case, as close as possible.

As for procedures, the techniques originally used for the application of gold leaf can essentially be two: water gilding and oil gilding.

Water Gilding

Water gilding, used since the 1200s, requires meticulous preparation of the surface, including the application of several layers of gesso mixed with rabbit skin glue, followed by several layers of bole, a special fatty earth that facilitates the adhesion of the gold leaf. The gold leaf is then applied using a water gilding technique, a water bath that allows the gold leaf to firmly attach to the surface. This is the oldest technique and is still used today for its ability to confer brilliance and luster to decorated objects, making it ideal for particularly precious artifacts.

Oil Gilding

Oil gilding, until the 19th century, was mainly used for small finishes or, very rarely, for gilding miniatures on paper. Following the formulation of Cennino Cennini (14th century), the oil used is typically a mixture of boiled linseed oil, white lead, and a variable amount of copper green. Antique frames made using this technique are very rare.

Gilding of Frames between the Middle Ages and the Renaissance

In the Middle Ages and the Renaissance, the most widespread technique was water gilding, and for this reason, bole plays a fundamental role in gilding. It acts as protection, covering the pores present on the wood, and preparing the surface for the application of gold. It can be of various colors:

• Yellow or red, mainly used in true gold leaf gilding;
• Black, used especially for silvering.

Once water gilding is done, it is possible to proceed to the polishing phase with the support of burnishing stones made of agate.

Before concluding, it is important to remember that in any restoration of antique frames, it is crucial to first verify the condition of the wood on which the gilding rests and intervene if necessary to repair it. This step must be carried out with great care to avoid losing carved or relief details on the artifact.