What is gold leaf gilding?
There are two main gold leaf gilding techniques, each suited to different types of surfaces and decorations, producing distinct final effects. The simpler method involves applying the leaf directly onto a surface prepared with a fluid oil/water-based sizing.
The more complex method involves applying the gold leaf over a layer of clay, called bole. This is traditionally known as water gilding, or “bole gilding,” which has been used throughout history for icons, frames, and wood. The colour of the clay subtly shows through the gold, giving your finished surface a rich depth and dimension. Water gilding also allows the gilder to burnish the surface for a richer shine, which is not possible with the single-sizing method.
You can choose your technique depending on the decoration and the surface. All outdoor and indoor projects on stone and metal will require an oil-based gilding size, whereas only water gilding or a water-based size can be used for interior gilding on plaster and wood.
Surface preparation
Before applying the gilding size or bole, your surface must be sealed and ready to receive the gold. Gesso or shellac can be used for this purpose – these can be applied in layers and sanded once fully dry.
Gesso will provide a smoother base layer to build upon, while shellac will preserve the natural grain or texture of your surface. You can also apply shellac over your dry gesso base to seal it. We offer a choice of clear or blonde shellacs.
Gilding: the process
Surface preparation
The gilding process begins with preparing the surface. It must be clean, dry, and properly sealed before applying the sizing or bole. Gesso provides a smooth base that can be sanded once dry, while shellac seals the surface while preserving its natural grain. A layer of shellac can also be applied over dry gesso to further strengthen the preparation.
Applying the sizing
Once the surface is ready, the sizing is applied and left to reach the correct tackiness – that is, no longer wet but slightly sticky. This stage is crucial, as it is when the gold leaf can be applied. Carefully lift the leaf from the booklet and place it onto the sized area, then gently smooth it with a gilding brush so it conforms to any relief. Once all the sheets are in place, leave to dry for a few hours before lightly brushing the surface to remove any loose fragments and reveal an even shine. Small uncovered areas can be touched up with pieces of gold leaf.
Protection
The final step is to protect the gilding if necessary. Genuine gold of 22 carats and above does not tarnish and can remain unvarnished, except in areas subject to frequent handling. Lower-carat gold or imitation metallic leaf, however, should be sealed to prevent tarnishing. Shellac, which dries quickly, is the traditional varnish used to protect gilding, as well as to seal absorbent surfaces before applying the leaf.
THE TWO TYPES OF GILDING
WATER GILDING (BOLE OR “PLATE” GILDING)
The gilding bole, or “plate” as it is sometimes called, can be used with either an oil- or water-based clay size. It provides a stable and flexible base for gilding wood or plaster indoors, ensuring a high-quality, durable, and even surface. The clay should always be diluted with rabbit-skin glue, which softens it, thins it, and acts as a fixative. The bole can be polished using a burnisher to achieve a smooth and shiny effect.
Traditionally, clays were simply the colour of the earth from which they were sourced, giving them a reddish hue; today, they are available in a range of colours. The colour of the clay subtly shows through the gold, giving the surface its final tone.
Mix the clay with twice its volume of a warm solution of Charbonnel rabbit-skin glue. Your surface must first be sealed before carefully applying the clay base in successive layers, allowing each layer to dry in between. Once the final layer is completely dry, the surface can be sanded with 400-grit sandpaper, and the bole can be polished with a cloth before gilding. A water- or oil-based sizing is then applied over the clay using a suitably sized brush.
We offer Charbonnel gilding bole, a finely ground clay base available in yellow, red, or black options, which can be mixed to create a custom colour.
SINGLE-SIZE GILDING
Simpler than traditional water gilding, water-based sizing generally produces less shiny effects because it cannot be burnished. In fact, using a burnisher will tear the gold leaf, as it remains flexible even when dry.
It is essential to consider the surface and context of your project when deciding which product to use. For stone, metal, exterior plaster, and wood (ideal for gates, railings, monuments, statues, domes, walls, frameworks, and lead figures), use an oil-based gilding size. For interior wood and plaster, use a water-based gilding size.
Oil-based gilding size
Surfaces gilded with oil-based size have the advantage of being water-resistant and more durable, capable of withstanding extreme weather conditions. If you are using a cheaper metal leaf, such as Dutch metal leaf or aluminium leaf, choose the oil-based method.
We offer two types of lead-free oil-based gilding sizes, each with different waiting times between applying the size and laying the gold leaf: 12-Hour Gold Size or 3-Hour Gold Size. The choice depends on the time available, environmental conditions, and project location.
12-Hour Gold Size is ideal for large surfaces, outdoor work, and dry, dust-free climates. The result will be shinier, richer, and more durable due to a stronger size film than the 3-Hour variant.
3-Hour Gold Size is designed for small surfaces, interior work, humid or dusty conditions, or times when 12-Hour Gold Size cannot be used.
Times may vary depending on environmental conditions; for example, in dry weather, the gold leaf can be applied 1–2 hours earlier than indicated, or up to 1–1.5 hours later. Both mixes can withstand temperatures down to -5 °C.
Water-based gilding size
Our water-based gilding size is ideal for interior wood and plaster. The fluid acrylic resin formula is water-soluble and designed for thin layer applications.
For maximum absorbency, dilute the first coat with 20% water, then apply a second coat at full strength. Allow at least 20 minutes before applying the gold leaf – it should still be slightly tacky and ready to receive the leaf for up to 24 hours afterwards.
TOOLS AND ACCESSORIES FOR THE GILDER
Gilding Bole
For water gilding techniques, we offer Charbonnel gilding bole in the form of a finely ground clay paste. The bole comes in 3 mixable colours for a personalised finish: red, yellow, and black.
Gilding Size
Discover our complete range for oil or water gilding. We offer an oil-based range including 3- or 12-hour gilding sizes, as well as a water-soluble acrylic resin size for water gilding and interior work.
Gilding Glue
Gilding glue is traditionally made from rabbit skin and is necessary to dilute and fix the bole when using the water gilding method.Our rabbit skin glue is available in granule form, which is dissolved in hot water to create an adhesive liquid, using a ratio of 5–8g of granules per 100g of water.
Gilding Knife
This straight double-edged blade is used to cut the gold leaf sheets placed on the cushion.
Gilding Brushes
You will need a range of brushes for the different stages of gilding. We offer four styles and a complete brush set.Our Burnishing Brush is used with gilding bole to polish the surface once dry before applying the gold leaf. It is an extremely stiff brush, tied with Kolkata silk thread.The Round Brushes are used to press the gold leaf onto your gilding surface when using either water- or oil-based size.The Stuffing Brushes are used to push the gold leaf onto the surface and are always used dry.The Finishing Brush has soft bristles tied with silk and is used to apply your final varnish layer.Our set of 13 brushes gives you everything you need from mixing to brush application.