The use of gold leaf in decorative painting Automatic translate

Gold leaf (from the Old Russian word "susalo " meaning "face" or "obverse") is a thin sheet of gold used for decorative surface coating. The material is used in icon painting, easel painting, architectural decoration, book miniatures, and restoration. The thickness of the sheets varies from 100 nanometers (0.1 µm) to several microns, which determines the specific physical properties of the material and the methods of working with it. Depending on the content of impurities (ligatures), the color of the gold varies from greenish and white to reddish, which is actively used by artisans to create coloristic effects.

Physicochemical properties and production

Gold has a unique malleability that allows it to be flattened into translucent sheets without damaging the integrity of its structure.

Metallurgy and alloys

Pure gold (24 karat) is a chemically inert metal, resistant to oxidation and corrosion, ensuring the longevity of gold plating. However, to impart various shades and physical properties to the material, copper, silver, palladium, or nickel are added to the alloy.

• Yellow gold: A classic alloy with a small addition of silver and copper.
• White gold: Alloy with palladium or nickel.
• Green gold: An alloy with silver (electrum), known since antiquity.
• Red gold: Contains a higher percentage of copper.

Imitation techniques use gold leaf — an alloy of copper and zinc or aluminum that visually resembles gold but is susceptible to oxidation and requires mandatory coating with protective varnish.

Manufacturing technology (beating)

The production process, historically known as "gold-beating," involves several stages. First, a bar is cast and rolled into a thin ribbon. The ribbon is cut into squares and stacked in a "book," with each sheet interleaved with special paper or, in traditional technology, a bovine cecum (bodryush).

Modern research by Japanese artisans from Kanazawa, using the entsuke technique (using special paper made from gampi fibers soaked in persimmon juice and straw ash), has shown that under intense hammering, the gold crystal lattice deforms in a way that is uncharacteristic of room temperature. This allows for a thickness of 100 nm to be achieved while maintaining the sheet’s integrity. During hammering, the gold is flattened uniformly, which is critical for the optical properties of the resulting coating: uneven thickness can lead to stains during polishing.

Materials and tools for gilding

The quality of gilding directly depends on the preparation of the base and the binders used.

Primers (Gessellated Matter and Polyment)

In traditional water gilding, the base is gesso - a chalky ground on animal glue (usually rabbit or sturgeon).

• Levkas: Consists of finely dispersed chalk and glue. It is applied in multiple layers (up to 10-15), then sanded to a perfectly smooth finish.
• Bolus (Polyment): Clay rich in iron oxides, mixed with glue and sometimes wax or fats. Polyment is applied over the gesso to underlay the gold. The color of the polyment (red, yellow, or black) influences the shade of the gilding, as the thin sheets of gold are partially translucent. Red polyment imparts warmth and depth to the gold, yellow conceals any breaks, and black (used in ancient French and Chinese lacquer) creates a cool, harsh sheen.

Adhesives

1. Hide glue and fish glue: Used to prepare gesso and polish. They are reversible (dissolve in warm water), allowing for polishing gold with agate.
2. Mordan: An oil varnish with added siccatives. Used in oil gilding techniques. It comes with varying drying times (3 hours, 12 hours). Gold is applied to the mordan at the "tack" stage, when the varnish no longer smears but retains its tack.
3. Synthetic adhesives: In modern practice, especially in restoration, acrylic dispersions (e.g. Plextol B500) or water-soluble polymers (Aquazol) are used, which ensure stability and the absence of color changes over time.

Tools

• Gilder’s Cushion: A suede-covered board with a windbreak on which gold is cut.
• Gilder’s Knife: A sharp, long knife used for cutting sheets.
• Lampenzel (Gilder’s Tip): A flat brush made of squirrel or badger hair used to transfer gold leaf from a pillow to a surface. The artist often runs the brush across the hair or cheek to lightly electrify the bristles with the oils of the skin to help the gold adhere.
• Agate Burnisher: A polished agate stone of various shapes (fang, spatula), mounted on a handle. Used for polishing gold to a mirror finish using the glue gilding technique.

Basic gilding techniques

In decorative painting, two fundamental methods are distinguished: glue (polymer) and oil (mordan) gilding, as well as a number of specific artistic techniques.

Adhesive gilding (Water Gilding)

This is the most labor-intensive, but also the most valuable method, achieving the effect of a solid gold bar. This technique is used exclusively in interiors, as it is sensitive to moisture. The process involves:

1. Applying gesso and sanding.
2. Apply 3-4 layers of polish.
3. Wetting the polished area with a water-alcohol solution (vodka). The alcohol reduces surface tension, allowing the water to instantly soak into the clay and "attract" the gold leaf.
4. Sheet overlay.
5. Polishing with agate after drying. The pressure of the agate compacts the gold and polish, creating a mirror-like surface.

Oil Gilding

A simpler method suitable for exterior work (domes, façade decoration) and surfaces that cannot be polished (stone, metal). The surface is primed (often with red lead or modern primers) to prevent the varnish from being absorbed. Then, a mordan is applied. The gold is laid on the varnish while it is still tacky. The main difference from the glue method is that it cannot be polished to a mirror finish with agate. The surface remains matte or semi-gloss, matching the texture of the substrate. Oil-based varnishes tend to darken and change color over time, which should be taken into account during restoration.

Shell Gold

A technique of painting with gold powder. Sheets of gold leaf are ground by hand with gum arabic (a plant-based glue) or honey to a fine powder. The resulting mass is washed with water to remove excess binder and then dried. The material is applied with a brush, like regular watercolor. After drying, the surface appears matte, but can be polished with agate to achieve a high sheen (for example, in book miniatures or icon painting to draw fine lines — an assist ).

Historical and regional schools

Antiquity and Byzantium: Eglomise and Chrysography

In the Roman Empire and later in Byzantium, the technique of interpanel gilding, now known as eglomise (verre Églomisé), developed. The term, coined in the 18th century in honor of the French decorator Jean-Baptiste Glomy, describes the process of applying gold to the back of glass and then engraving it with a needle. In early Christian catacombs (4th century AD), the bottoms of glass vessels have been found with portraits engraved on gold foil sandwiched between two layers of glass. In Byzantine iconography, gold symbolized divine light, creating a transcendental space devoid of shadows and time.

Italian Renaissance: Pastiglia and Sgraffito

Italian masters of the 14th – 16th centuries brought gold decoration techniques to perfection.

• Pastiglia: A relief pattern made of liquid gesso, applied with a brush before gilding. After drying, the relief was gilded and polished along with the background, creating a complex play of light.
• Sgraffito: A scratching technique. A layer of tempera paint (often blue or red) was applied over polished gold. After drying, the paint was scratched along a stencil down to the gold layer, creating a fine gold pattern on a colored background. This technique was widely used to imitate precious fabrics on saints’ vestments.

Japan: Kirikane and Maki-e

In Japan, a goldsmithing technique known as kirikane (literally, "cut gold") was used to decorate Buddhist statues and scrolls. Craftsmen glued together several sheets of gold (heating them over diffusion welding coal) to create a thicker foil, which they then cut with a bamboo knife into fine threads and geometric shapes (diamonds, triangles). These elements were adhered to the surface of the sculpture using seaweed glue (funori). Although maki-e (lacquer painting) more often uses gold powder, it also uses fragments of gold foil ) hirame ), which are embedded in urushi lacquer and then polished.

Modern application and avant-garde

In the art of the 20th and 21st centuries, gold has ceased to be merely a symbol of sacredness or wealth, becoming an independent means of expression.

Gustav Klimt and the Golden Period

Austrian artist Gustav Klimt radically reimagined the use of gold leaf in easel painting. Studies of his works (such as "The Kiss") reveal a complex technique: he used not only gold leaf but also platinum and silver to create nuances of color. Klimt employed the technique of oil gilding, often painting with oil over gold, and also used gold powder to create shimmering textures. His approach combined the flatness of Byzantine mosaics with the eroticism of Art Nouveau.

Yves Klein’s Monochromes

In his Monogold series (early 1960s), French artist Yves Klein used sheets of gold leaf loosely attached to a surface so they could sway with the movement of air ("breathe"). In his works, such as the triptych "Monochrome and Fire" (1961), gold emerges as the quintessence of the absolute and immaterial, on par with his signature blue (IKB).

Contemporary artists

Contemporary artists are experimenting with the oxidation of imitation materials and textural contrasts. For example, Janine Lamberts creates large-scale installations by applying gold pieces like a mosaic, varying shades (moon gold, champagne) to create painterly effects. Technology allows gold to be applied to unconventional substrates such as concrete, plastic, and synthetic resins, using specialized pore-filling primers.

Pathology, conservation and restoration

The gilded surface, despite the chemical resistance of the metal itself, is a complex multi-layered structure that is susceptible to destruction.

Typical defects

1. Cleaving: Occurs due to the breakdown of the adhesive layer (degradation of animal glue) or movement of the wood base due to fluctuations in humidity.
2. Scuffs: Mechanical wear of a thin layer of gold (especially on raised areas of relief), revealing a red or yellow polish. In antiques, light scuffs are often preserved as a "patina of time."
3. Oxidation of Imitations: Leaf leaf and low-grade gold (less than 23 karat) may become darkly stained or turn green due to oxidation of the copper in the alloy if the protective varnish is damaged.

Materials and methods of restoration

Modern preservation is moving away from using only traditional materials in favor of synthetic polymers with better stability and reversibility.

• Paraloid B-72: An acrylic copolymer widely used to strengthen (consolidate) crumbling gesso and paint layers. It has high penetrating properties and does not yellow over time.
• Aquazol (poly-2-ethyl-2-oxazoline): A water-soluble polymer used as a replacement for animal glue when restoring gesso and craquelure. Its advantages include compatibility with traditional materials and high elasticity.
• Nano Gold Gel (NGG): The latest development (2024–2025) for the conservation of murals. This gel, based on gold nanoparticles and polymers, allows for the strengthening of the crumbling gold layer without altering its optical properties, which is critical for matte, unpolished surfaces.

When replacing lost gold, restorers often use a toning technique to prevent the new areas from standing out against the old gold. To achieve this, the new gold leaf is coated with transparent layers of watercolor or special glazes that imitate patina. If the loss is significant, oil gilding on mordant is used, as it is less invasive for the weakened base than the glue-and-polish method.

Water should not be used to clean gilded items (for adhesive gilding), as this can instantly wash away the layer along with the gesso. Special water-free solvents or dry cleaning methods are used. In the case of gold leaf, more vigorous cleaning is permissible if the protective varnish layer is preserved.

Innovations in gold extraction

In parallel with art, technologies for recovering gold from waste are developing (including during the restoration of large-scale objects or the recycling of electronics). New materials, such as aerogels based on amyloid fibrils from whey proteins or covalent organic frameworks (COFs), are capable of selectively extracting gold ions from complex solutions, converting them back into high-purity metallic nanoparticles. These technologies could find application in the environmentally friendly recycling of materials from gilding workshops.