A foil is a very thin sheet of

metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...

, typically made by hammering or rolling.Britannica, The Editors of Encyclopaedia. "foil". Encyclopedia Britannica, 6 Nov. 2008
https://www.britannica.com/technology/foil-metallurgy.
Accessed 11 September 2022. Foils are most easily made with

malleable Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

metal, such as

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...

, tin, and

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

. Foils usually bend under their own weight and can be torn easily. For example,

aluminium foil Aluminium foil (or aluminum foil in North American English; often informally called tin foil) is aluminium prepared in thin metal leaves with a thickness less than ; thinner gauges down to are also commonly used. Standard household foil is typ ...

is usually about 1/1000 inch (0.03 mm), whereas

(more malleable than aluminium) can be made into foil only a few

atoms Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas ...

thick, called

gold leaf Gold leaf is gold that has been hammered into thin sheets (usually around 0.1 µm thick) 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-kara ...

. Extremely thin foil is called

metal leaf A metal leaf, also called composition leaf or schlagmetal, is a thin foil used for gilding and other forms of decoration. Metal leaves can come in many different shades. Some metal leaves may look like gold leaf but do not contain any real gold. ...

. Leaf tears very easily and must be picked up with special brushes. Foil is commonly used in household applications. It is also useful in survival situations, in the form of a " space blanket", where the reflective surface reduces the degree of

hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...

caused by thermal radiation.

References

Metalworking {{Metalworking-stub

See also

References