Gilding is an art that requires dexterity, savoir-faire and skill, qualities that craftsmen obtain after years of experience. There are two basic techniques in applying gold or metal leaf to surfaces: oil and water gilding. Both techniques employ a glue to adhere the leaf to the substrate, but the difference lies in the type of glue. This technique uses a water-based glue or size.
Gilding involves two specific stages:[LIST=1][*]Preparing the support[*]Laying the gold leaf[/LIST]When using a gilding bole, you need to prepare the surface before the gold leaf is applied. Wood is generally used because it has a stable shape: sizing and several layers of white chalk mixed with hide glue are applied to the support.
There are two different stages to preparing hide glue:[LIST=1][*]Hide glue is usually available in a block or in grain form (either rabbit or bovine skin). You need to soak the hide glue first. Add water until it reaches the level of the glue. Leave to soak for 24 hours, until it is completely soft.[*]Remove from the water, drain and melt in a bain-marie, without boiling, stirring continuously. When the glue has melted, remove from the heat.[/LIST]1 part of glue for 7 parts of water
When melted, add the hide glue to white chalk. Reheat the mixture in a bain-marie when it cools. Apply the mixture to the surface. Between each layer, you need to sand the surface until smooth. This primer is the base onto which you brush the gilding bole. The bole is a paste that comes in different colours: yellow, red and black. Mix this bole with twice its volume in warm hide glue. You’ll need two layers of bole.
Once the bole is dry, wipe the surface with a cloth to remove dust. Use a squirrel hair brush to moisten all the surfaces on which the bole was applied: if water drips are slightly coloured, bole adherence is correct. Apply the gold leaves to the moist bole and leave to dry. Burnish the surface with agate.
Burnishing involves rubbing with agate stone in the shape of the surface, by pressing relatively hard to inlay the gold sheet into the bole. There are different shaped agates to suit different contours and motifs for reliefs and sculptures.
Gilding is complete. Objects will retain their sheen for many years.