Gold leaf is gold that has been hammered into extremely thin sheets by goldbeating and is often used for gilding. Gold leaf is available in a wide variety of karats and shades. The most commonly used gold is 22-karat yellow gold.
Gold leaf is sometimes confused with metal leaf but they are different products. The term metal leaf is normally used for thin sheets of metal of any color that do not contain any real gold. Pure gold is 24 karats. Real yellow gold leaf is about 91% pure gold. Silver colored white gold is approximately 50% pure gold.
Layering gold leaf over a surface is called gold leafing or gilding. Traditional water gilding is the most difficult and highly regarded form of gold leafing. It has remained virtually unchanged for hundreds of years and is still done by hand.
Gold leaf in art
Gold leaf is sometimes used in art in a "raw" state, without a gilding process. In cultures including the European Bronze Age it was used to wrap objects such as bullae simply by folding it tightly over, and the Classical group of gold lunulae are so thin, especially in the centre, that they might be classed as gold leaf. It has been used in jewellery in various periods, often as small pieces hanging freely.
Gold leaf has traditionally been most popular and most common in its use as gilding material for decoration of art (including statues and Eastern Christian icons) or the picture frames that are often used to hold or decorate paintings, mixed media, small objects (including jewelry) and paper art. Gold glass is gold leaf held between two pieces of glass, and was used for decorated Ancient Roman vessels, where some of the gold was scraped off to form an image, as well as tesserae gold mosaics. "Gold-ground" paintings, where the background of the figures was all in gold, was introduced in mosaics in later Early Christian art, and then used in icons and Western panel paintings until the late Middle Ages; all techniques use gold leaf. "Gold" frames made without leafing are also available for a considerably lower price, but traditionally some form of gold or metal leaf was preferred when possible and gold leafed (or silver leafed) moulding is still commonly available from many of the companies that produce commercially-available moulding for use as picture frames.