From pre-history, gold has been a material of wealth; so what could be more pious than to offer it up to the gods through art? Seemingly immune to the passing years; it did not tarnish and lose its splendour. The use of gold in medieval art shows us more clearly than anything else how the nature of materials took precedence over any concern for realism. Until at least the 14th century, holy figures on altar panels are framed not by nature’s skies or foliage but by a golden field that has neither depth nor shadow. In later ages this metallic sheen was pushed back on to the gilded frame that held the canvas; but for the medieval artist gold was a colour in its own right. It was applied to gessoed panels in the form of thin sheets: gold leaf was beaten by hand between sheaves of leather till they were as thin as tissue.
The slightest film of adhesive, traditionally in the form of a weak gelatine solution, will bind these delicate sheets to the surface. Laid gold leaf conforms to all the irregularities of the underlying surface. This produces a rather flat, opaque yellow appearance. Only if the gold is rubbed intimately (burnished) with a rounded stone or a tooth onto the surface does ‘The gold then becomes almost dark from its own brilliance’. Burnishing literally means ‘making brown’, darkening the gold in the shadows, while making the highlights more reflective.
If gold is traditionally twinned with the Sun, then silver is equated with the Moon. As a precious metal, silver has long held an important position. From Ancient Egypt, silver beads and other small objects have been found. It has been used ever since for jewellery, medals and coins. Although the metal occurs naturally it is more often mixed with other elements and must be extracted by smelting. With the discovery of the New World, the Spanish empire exported around 150,000 tonnes of the metal from silver mines in South and Central America. At the time, this accounted for around 80% of the world’s supply and was a major contributor financially to Spain’s dominance within Europe. Argentina, was named by the Spanish after the Latin ‘argentum’, meaning silvery.
For artists, before the use of lead pencils in the 16th century, sketches were made using ‘silverpoint’ whereby timber dowels with an inserted rod of silver wire were applied to drawing or painting surfaces prepared with a chalk or bone ash ground. The silver abraded onto the surface and the initial mark, starting as a silvery-grey, oxidised and turned almost black. It could not be ‘rubbed-out’ like graphite pencils, but allowed for very fine under-drawing that would not ‘lift’ and discolour the paint painted over the top.
Copper was discovered in prehistory, some of the earliest copper works are beads dating back 9,000 years. Two thousand later, almost synchronistically across the globe, copper smelting was first invented, allowing for the manufacture of alloys such as bronze, critical to the making of tools. Bronze is formed by the mixing of copper with tin and is still used in the casting of sculpture. Known to the ancient world, copper was essential to the Egyptians, Greeks and Romans.
Cyprus was famous in antiquity for its copper. In fact the very word copper is derived from the Greek name for the island, Kupros. Cypriots first worked copper 6000 years ago, fashioning tools from native deposits, which at that time could still be found as a pure ore in the ground. In painting, copper was used in panels as a support, the smooth, rigid plates permitted extraordinarily controlled brushwork. Painting on copper appeared in Florence in the late 16th century and was ideal for the painting of portrait miniatures. It has a long history in use for intaglio printmaking, where its hardness allows for editioning without loss of quality of line in the gravure over multiple prints.