art history Art history is the study of aesthetic objects and visual expression in historical and stylistic context. Traditionally, the discipline of art history emphasized painting, drawing, sculpture, architecture, ceramics and decorative arts; yet today ...

and the craft of gilding, shell gold is gold paint given its colour by very small pieces of real gold, normally obtained either from waste gold from

goldsmithing A goldsmith is a metalworker who specializes in working with gold and other precious metals. Nowadays they mainly specialize in jewelry-making but historically, goldsmiths have also made silverware, platters, goblets, decorative and serviceable ...

and gilding, ground-up gold leaf, or fragments that have come off a

gold-ground Gold ground (both a noun and adjective) or gold-ground (adjective) is a term in art history for a style of images with all or most of the background in a solid gold colour. Historically, real gold leaf has normally been used, giving a luxuriou ...

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 Mortar and pestle is a set of two simple tools used from the Stone Age to the present day to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen, laboratory, and pharmacy. The ''mortar'' ( ...

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, also known as gum sudani, acacia gum, Arabic gum, gum acacia, acacia, Senegal gum, Indian gum, and by other names, is a natural gum originally consisting of the hardened sap of two species of the ''Acacia'' tree, '' Senegalia se ...

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

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

. 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, where as powdered gold does.

References

{{reflist Gilding Painting Paints