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Aluminium foil (or aluminum foil in American English; occasionally called tin foil) is aluminium prepared in thin metal leaf. The foil is pliable and can be readily bent or wrapped around objects. Thin foils are fragile and are sometimes lamination with other materials such as or paper to make them stronger and more useful.
Annual production of aluminium foil was approximately in Europe in 2014, and in the U.S. in 2003. "Foil & Packaging". . The Aluminum Association (USA). Approximately 75% of aluminium foil is used for packaging of , cosmetics, and chemical products, and 25% is used for industrial applications (e.g., thermal insulation, electrical cables, and electronics). It can be easily recycled.
Aluminium foil supplanted tin foil in the mid 20th century. In the United Kingdom and United States it is often informally called "tin foil", just as are often still called "". are sometimes mistaken for aluminium foil, but are actually polymer films coated with a thin layer of aluminium.
The first audio recordings on phonograph cylinders were made on tin foil.
In 1911, Bern-based Tobler began wrapping its chocolate bars in aluminium foil, including the unique Triangular prism chocolate bar, Toblerone.
Foil may have a non-stick coating on only one side.
Although aluminium is non-magnetic, it is a good conductor, so even a thin sheet reflects almost all of an incident electric wave. At frequencies more than 100 MHz, the transmitted electric field is attenuated by more than 80 (dB), that is less than 10−8 = 0.00000001 of the power gets through.. graphs reflection loss for copper and shows electric field and plane wave losses at greater than 90 dB.
Thin sheets of aluminium are not very effective at attenuating low-frequency magnetic fields. The shielding effectiveness is dependent upon the skin depth. A field travelling through one skin depth will lose about 63% of its energy (it is attenuated to 1/ e = 1/2.718... of its original energy). Thin shields also have internal reflections that reduce the shielding effectiveness..
The two sides in contact with each other are matte, and the exterior sides become shiny. The difference in thermal properties between the two sides is imperceptible without instrumentation. By Kirchhoff's law of radiation, increased reflectivity decreases both absorption and emission of radiation.
Aluminium foil is also used for barbecue delicate foods.
As with all metallic items, aluminium foil reacts to being placed in a microwave oven. This is because of the electromagnetic fields of the microwaves inducing electric currents in the foil and high voltage at the sharp points of the foil sheet; if the potential is sufficiently high, it will cause to areas with lower potential, even to the air surrounding the sheet. Modern microwave ovens have been designed to prevent damage to the cavity magnetron tube from microwave energy reflection, and aluminium packages designed for microwave heating are available.Huss, G. (1997) Microwaveable Packaging and Dual-Ovenable Materials in The Wiley Encyclopedia of Packaging Technology, 2nd ed., edited by Brody, A. and Marsch, K. New York, John Wiley and Sons
Aluminium foil submerged in a baking soda solution can be used to polish metals such as silver and gold via electrolytic cleaning, as it is a more Galvanic series metal than either. A similar method can be used to produce silver substrates for Raman spectrography.
History
Precursors
Foil made from a thin leaf of tin was commercially available before its aluminium counterpart. Tin foil was marketed commercially from the late nineteenth into the early twentieth century. The term "tin foil" survives in the English language as a term for the newer aluminium foil. Tin foil is less ductility than aluminium foil and tends to give a slight tin taste to food wrapped in it. Tin foil has been supplanted by aluminium and other materials for wrapping food.
Invention
Tin was first replaced by aluminium in 1910, when the first aluminium foil rolling plant, was opened in Kreuzlingen, Switzerland. The plant, owned by , the aluminium manufacturers, was founded in 1886 in Schaffhausen, Switzerland, at the foot of the Rhine Falls, whose energy powered the process. In December 1907, Neher's sons, along with Dr. Lauber, had invented the endless rolling process, by which they discovered that aluminium foil could be used as a protective barrier.
Properties
Aluminium foil has a thickness less than ; thinner gauges down to are also commonly used. Standard household foil is typically thick, and heavy-duty household foil is typically .
Manufacture
The continuous casting method is much less energy-intensive and has become the preferred process.Robertson, G. (2006). 2nd ed. Food Packaging, Principles and Practise, Boca Raton, FL, Taylor & Francis Group: . Chapter 7: Metal Packaging Materials. It is difficult to produce rollers with a gap fine enough to cope with the foil gauge, and to avoid this, as well as reducing tearing, increasing production rates, and controlling thickness, (2025). 9780471656531, Wiley. ISBN 9780471656531 for the final pass when producing thicknesses below , two sheets are rolled at the same time, doubling the thickness of the gauge at entry to the rollers. After the rollers, the two sheets are separated, which produces foil with one shiny side and one matte side.
Uses
Aluminium foil is widely sold into the consumer market, often in rolls of width and several metres in length. Examples of products
Environmental issues
Some aluminium foil products can be recycling at around 5% of the original energy cost.
See also
External links
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