art history Art history is the study of Work of art, artistic works made throughout human history. Among other topics, it studies art’s formal qualities, its impact on societies and cultures, and how artistic styles have changed throughout history. Tradit ...

and the craft of

gilding Gilding is a decorative technique for applying a very thin coating of gold over solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, the metal below was tradi ...

, shell gold is gold paint given its colour by very small pieces of real gold, normally obtained either from waste gold from goldsmithing and gilding, ground-up

gold leaf upA gold nugget of 5 mm (0.2 in) in diameter (bottom) can be expanded through hammering into a gold foil of about 0.5 m2 (5.4 sq ft). The Japan.html" ;"title="Toi gold mine museum, Japan">Toi gold mine museum, Japan. Gold leaf is gold that has ...

, or fragments that have come off a gold-ground painting or other gilded object. The name comes from the medieval habit of using sea-shells to hold pigments and paints (of all colours) while painting. In painting it was usually used for details and highlights.Nuechterlein, Jeanne, "A brief overview of gilding techniques", in "From Medieval to Modern: Gold and the Value of Representation in Early Netherlandish Painting", 2013, University of York, Department of History of Art, History of Art Research Portal
online
(or PDF) A common source is the collecting and processing of flakes of elemental gold that have flaked away from a surface during the process of gilding it. Once the flakes of leftover gold (called "skewings") have been gathered, they are mixed with a small amount of honey and ground together with a

mortar and pestle A mortar and pestle is a set of two simple tools used to prepare ingredients or substances by compression (physics), crushing and shear force, grinding them into a fine Paste (rheology), paste or powder in the kitchen, laboratory, and pharmacy. ...

until they become a powder. The honey is then removed by placing this mixture in a bath of hot water, leaving the gold flakes to collect at the bottom. The upper layer of water is poured off and the process is repeated several times, the last few with deionized water. Following the final rinse, the flakes are left to dry. Once the water has nearly evaporated, a drop of concentrated

gum arabic Gum arabic (gum acacia, gum sudani, Senegal gum and by other names) () is a tree gum exuded by two species of '' Acacia sensu lato:'' '' Senegalia senegal,'' and '' Vachellia seyal.'' However, the term "gum arabic" does not indicate a partic ...

is added and mixed into the flakes, creating a basic paint with gold flakes/ dust as

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

. The paint may be applied to a surface using either a brush or the tip of a finger, and can be "reactivated" by only the moisture in an exhaled breath of air. Shell gold and powdered gold are the two principal forms of gold used for making repairs in a surface which has been previously gilded but has been damaged. Shell gold does not require any

sizing Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption ...

, where as powdered gold does.

References

{{reflist Gilding Painting Paints