HISTORICAL MATERIALS/TECHNIQUES

GILDING

Contents

What is Gilding?

​Gilding is the act of covering a base or common material with a thin layer of gold. Other metals, including silver or metal alloys, have also been used in gilding. However, the advantage of using gold gilding is its high stability and resistance to tarnishing and discoloration. Gold is also highly malleable and can be hammered into very thin sheets without fracturing.

History of Gilding

Gilding techniques can be traced back to as early as 3000 B.C.E., beginning first in the Middle East and later spreading to the Far East and eventually Europe. One of the earliest bibliographical references to the actual process of gilding occurred in the first century B.C.E. Prior to this date terms like “gold,” “golden,” and “gilding” were used ambiguously. With the help of scientific analysis, scholars can now learn more about an object’s history by studying its technical execution and provenance. Technical investigations have revealed that there were several different methods for adhering gold, silver, or tin to a surface. These include the use of gold foil, gold leaf and gold amalgam (a solution of gold in mercury typically used on metal objects).

The production of gold leaf began towards the end of the third millennium B.C.E., when craftsmen discovered how to refine the metal and hammer it into thin sheets. Gold leaf became popular around the 12th century in Europe and was traditionally prepared during Medieval times by first rolling or beating gold ducats (trade coins used in Medieval Europe) to the approximate thickness of foil. As the metal became progressively thinner, it became difficult to prevent the foil from adhering to nearby moist or greasy surfaces. To prevent this from occurring, Thompson describes how “the gold beaters [would] put a little square of the thin metal in the middle of a square of paper or parchment and other squares of metal above it in order until they have quite a pile; and then they [would] very skillfully hammer it until the little squares of metal have spread out to the edges of the parchment.” These squares are then cut into small squares again and the process repeated. For the last hammering step when the gold has reached its thinnest point, a special kind of parchment called “goldbeaters’ skin” (made from the internal membrane of a calf’s intestine) was placed in between the layers of foil. According to Cennino Cennini, approximately 145 leaves could be made out of one ducat, and one Venetian ducat weighed roughly 54 Troy grains. Cennino, however, preferred his gold leaf to be thicker and recommended that only 100 leaves be produced from one ducat. Today, commercially available gold leaf is much thinner, requiring special tools for handling and application.

Primary Gilding Techniques

Water Gilding – In water-gilding, a material called bole is first applied to the surface (typically a gesso or chalk ground layer).  Bole is a type of clay (traditionally in red or yellow ochre) mixed with animal glue and water. The warm color of the bole helps diminish the greenish color that appears when pure gold leaf is applied directly to a white surface. Once the bole dries, it is burnished using a coarse cloth (e.g. horsehair cloth) until a fine, smooth sheen is achieved. The glue in the bole can then be re-activated by spreading water (sometimes mixed with a bit of alcohol) over the surface. The gold leaf is then carefully placed on the moistened bole and allowed to dry. After several hours the gold leaf is burnished with a hard, smooth object (historically dog’s teeth were used) such as an agate stone, until a mirror-like surface is achieved. Additional embellishments can then be added such as punchwork, sgraffito, and incising.

Mordant Gilding – The term mordant literally means “to bite.” Some mordants contain plant gums or glair (egg white) while others are oil-based. Oil mordants contain oil-resin mixtures or oils that are chemically modified to be thick and tacky (e.g. heat-bodied or sun-thickened oils). These are brushed directly to the surface and allowed to partially dry before the gold leaf is applied. Once the oil mordant is completely set, the excess gold is removed. In general, oil-based mordants were used for panels, walls, and wood.

Decorative Gilding Techniques

Sgraffito is a method of applying paint to a gilded surface and then selectively removing the paint so that areas of the gold show through. This technique allowed painters to create intricate, gold detailing that would not have been possible using selective water gilding.

Pastiglia is a technique used to create a low relief decoration. Typically, pastiglia is accomplished by applying layers of gesso on the surface. Extra layers of gesso are applied to create areas of higher relief.

Punchwork is a design technique accomplished by indenting the gold leaf surface without breaking it. A punch, or a pencil-like metal tool with a design on one end, would be placed in the desired spot (design-end pressed onto the surface) and then hammered on the other end.

Incising is similar to punchwork in that it is a technique that indents the surface of the gold leaf into a particular design. However, instead of hammering a punch, incising utilizes a metal stylus to press a design into the gold. This technique allows for more fluid and inventive designs.

Related Links and Resources

Water Gilding Tutorial – Youtube

Glossary for Gilding Terms

Gilding Techniques and History – Aidan Hart

“The Art of Gilding” – Conservation and Design International Newsletter

References

Bigelow, Deborah. Gilded Wood Conservation and History. Madison, CT: Sound View Press, 1980.

Cennini, Cennino. The Craftsman’s Handbook “Il Libro dell’ Arte. Translated by Daniel V. Thompson. 1933. Reprint. New York: Dover Publications, 1960.

Drayman-Weisser, Terry. Gilded Metals: History, Technology and Conservation. London: Archetype Publications, 2000.

Mactaggart, Peter and Mary Mactaggart. Practical Gilding. London: Archetype Publications, 1984.

Thompson, Daniel V., Materials and Techniques of Medieval Painting. New York: Dover Publications, Inc., 1956.

Whitley, Kathleen P., The Gilded Page: The History and Technique of Manuscript Gilding. New Castle, Delaware: Oak Knoll Press & The British Library, 2000.