Description
Aluminium foil is aluminium prepared in thin metal leaves, with a thickness less than 0.2 millimetres (0.0079 in), thinner gauges down to 0.006 mm are also commonly used.[1] In the USA, foils are commonly gauged in mils. The foil is pliable, and can be readily bent or wrapped around objects. Thin foils are fragile and are sometimes laminated to other materials such as plastics or paper to make them more useful. Aluminium foil supplanted tin foil in the mid 20th century.
Annual production of aluminium foil was approximately 800,000 tonnes (880,000 tons) in Europe[1] and 600,000 tonnes (660,000 tons) in the USA in 2003.[2] Approximately 75% of aluminium foil is used for packaging of foods, cosmetics, and chemical products, and 25% used for industrial applications (e.g. thermal insulation, cables and electronics).[2]
In North America, aluminium foil is known as aluminum foil. It is also sometimes called Reynolds wrap after Reynolds Metals, the leading manufacturer in North America. In the United Kingdom and United States it is, informally, widely called tin foil, for historical reasons. Metallised films are sometimes mistaken for aluminium foil, but are actually polymer films coated with a thin layer of aluminium.
Properties
Aluminium foils thicker than 0.025 mm (0.00098 in) are impermeable to oxygen and water. Foils thinner than this become slightly permeable due to minute pinholes caused by the production process.
Aluminium foil has a shiny side and a matte side. The shiny side is produced when the aluminium is rolled during the final pass. It is difficult to produce rollers with a gap fine enough to cope with the foil gauge, therefore, for the final pass, two sheets are rolled at the same time, doubling the thickness of the gauge at entry to the rollers. When the sheets are later separated, the inside surface is dull, and the outside surface is shiny. This difference in the finish has led to the perception that favouring a side has an effect when cooking. While many believe that the different properties keep heat out when wrapped with the matte finish facing out, and keep heat in with the matte finish facing inwards, the actual difference is imperceptible without instrumentation.[7] The reflectivity of bright aluminium foil is 88% while dull embossed foil is about 80%.[4]
Usage: Insulation
Aluminium foil is widely used for thermal insulation (barrier and reflectivity), heat exchangers (heat conduction) and cable liners (barrier and electrical conductivity). Aluminium foil's heat conductive qualities make it a common accessory in hookah smoking: a sheet of perforated aluminium foil is frequently placed between the coal and the tobacco, allowing the tobacco to be heated without coming into direct contact with the burning coal.
Copied from : en.wikipedia.org/wiki/Aluminium_foil
something about foil insulation, it can be wall covering for thermal insulation, roof sheeting for heat insulation, pipe packing paper for heat energy prevention, radiant barrier in buildings, and automotive.