Metal leaf
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Metal leaf is a thin foil used for decoration. It is also called Composition leaf or Schlagmetal. Metal leaf can come in many different shades. Some metal leaf looks like gold leaf but does not contain any real gold; this is often referred to as imitation leaf.
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[edit] Process
Metals that are made into metal leaf need to be highly malleable. They can be pounded into sheets well below a micrometre in thickness without breaking or tearing. The typical thickness of gold leaf is about 100 nanometres or 0.0001 mm[1]. When made by hand, small pieces of metal are placed between sheets of parchment and pounded repeatedly with wooden mallets. As the metal thins out, it forms large sheets. These sheets are divided and the process repeated. The final sheets of metal are trimmed, cut to various sizes, and sandwiched between sheets of paper to protect them. At a thickness of 100 nm one square metre of gold leaf corresponds to 0.1 cubic centimetre or just 2 grams of gold. In imperial measurements, one ounce (28 g) of gold corresponds to about 200 square feet (about 20 m2) of gold leaf.
[edit] Uses
[edit] Decoration
Metal leaf is most often used for decoration. Before the discovery of electroplating it was the only cost effective way to gild statues, rooftops or other objects. It is still used in some places, such as Atlanta's and Denver's Capitol building.
[edit] Confection
Gold and silver leafs are non-toxic when labeled as food-grade and so can be used to decorate food or drink. They can be often found in a number of desserts including chocolates and Mithai. A recent trend has been the inclusion of floating bits of gold leaf in liquors such as Goldschläger.
In Asian countries, edible gold is sometimes used in various foodstuffs. It was also used in coffee, especially during Japan's Bubble economy.
[edit] See also
[edit] Notes
- ^ Holleman-Wiberg: Lehrbuch der anorganischen Chemie, Walter de Gruyter GmbH, 1985.