![Aluminio](https://upload.wikimedia.org/wikipedia/commons/d/dc/Aluminio.jpg)
Aluminium foil (or aluminum foil in
North American English
North American English (NAmE, NAE) is the most generalized variety of the English language as spoken in the United States and Canada. Because of their related histories and cultures, plus the similarities between the pronunciations (accents), v ...
; often informally called tin foil) is
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. I ...
prepared in thin
metal leaves with 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 . The
foil
Foil may refer to:
Materials
* Foil (metal), a quite thin sheet of metal, usually manufactured with a rolling mill machine
* Metal leaf, a very thin sheet of decorative metal
* Aluminium foil, a type of wrapping for food
* Tin foil, metal foil ...
is pliable, and can be readily bent or wrapped around objects. Thin foils are fragile and are sometimes
laminated
Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materia ...
with other materials such as
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
s or
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
to make them stronger and more useful.
Annual production of aluminium foil was approximately in Europe
and in the U.S.
["Foil & Packaging"]
. The Aluminum Association (USA). in 2003. Approximately 75% of aluminium foil is used for
packaging
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a co ...
of
food
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
s,
cosmetics
Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...
, 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
Tin foil, also spelled tinfoil, is a thin foil made of tin. Tin foil was superseded after World War II by cheaper and more durable aluminium foil, which is still referred to as "tin foil" in many regions (an example of a misnomer).
History
...
in the mid 20th century. In the United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
and United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
it is often informally called "tin foil", just as steel can
A steel can, tin can, tin (especially in British English, Australian English, Canadian English and South African English),
steel packaging, or can is a container for the distribution or storage of goods, made of thin metal. Many cans re ...
s are often still called "tin can
A steel can, tin can, tin (especially in British English, Australian English, Canadian English and South African English),
steel packaging, or can is a container for the distribution or storage of goods, made of thin metal. Many cans re ...
s". Metallised film Metallised films (or metallized films) are polymer films coated with a thin layer of metal, usually aluminium. They offer the glossy metallic appearance of an aluminium foil at a reduced weight and cost. Metallised films are widely used for decorati ...
s are sometimes mistaken for aluminium foil, but are actually polymer films coated
A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Powder ...
with a thin layer of aluminium. In Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, aluminium foil is widely called ''alfoil''.
History
Before aluminium foil
Foil made from a thin leaf of tin
Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal.
Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
was commercially available before its aluminium counterpart. Tin foil
Tin foil, also spelled tinfoil, is a thin foil made of tin. Tin foil was superseded after World War II by cheaper and more durable aluminium foil, which is still referred to as "tin foil" in many regions (an example of a misnomer).
History
...
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 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 ...
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.
The first audio recordings on phonograph cylinders
Phonograph cylinders are the earliest commercial medium for recording and reproducing sound. Commonly known simply as "records" in their era of greatest popularity (c. 1896–1916), these hollow cylindrical objects have an audio recording engra ...
were made on tin foil.
Invention
Tin was first replaced by aluminium in 1910, when the first aluminium foil rolling plant, Dr. Lauber, Neher & Cie. was opened in Emmishofen, Switzerland
). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
. The plant, owned by J.G. Neher & Sons, the aluminium manufacturers, was founded in 1886 in Schaffhausen
Schaffhausen (; gsw, Schafuuse; french: Schaffhouse; it, Sciaffusa; rm, Schaffusa; en, Shaffhouse) is a list of towns in Switzerland, town with historic roots, a municipalities of Switzerland, municipality in northern Switzerland, and the ...
, Switzerland, at the foot of the Rhine Falls
, photo = File:SBB RABe 514 DTZ Rheinfall.jpg
, photo_width = 280
, photo_caption = Rhine Falls with Rheinfall Bridge and Laufen Castle
, location = On the border between the cantons of Schaffhausen and Zürich next to Schaffhausen, i ...
, 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.
In 1911, Bern-based Tobler began wrapping its chocolate bars in aluminium foil, including the unique triangular
A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, any three points, when non- collinea ...
chocolate bar, Toblerone
Toblerone ( , ) is a Swiss chocolate brand produced in Bern. Toblerone is known for its distinctive shape, a series of joined triangular prisms and lettering engraved in the chocolate.
Since 2012, the brand has been owned by US company Mondele ...
.
The first use of foil in the United States was in 1913 for wrapping Life Savers
Life Savers (stylized as LifeSavers) is an American brand of ring-shaped hard and soft candy. Its range of mints and fruit-flavored candies is known for its distinctive packaging, coming in paper-wrapped aluminum foil rolls.
Candy manufacturer ...
, candy bars, and gum.[Hanlon, J. (1992). 1st ed. Handbook of Package Engineering, Lancaster, Pennsylvania, and Technomic Publishing: . Chapter 3 Films and Foils.]
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.] For thicknesses below , two layers are usually put together for the final pass and afterwards separated which produces foil with one bright side and one matte side. The two sides in contact with each other are matte and the exterior sides become bright; this is done to reduce tearing, increase production rates, control thickness, and get around the need for a smaller diameter roller.
Properties
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 (wrongly) that the different properties keep heat out when wrapped with the shiny finish facing out, and keep heat in with the shiny finish facing inwards, the actual difference is imperceptible without instrumentation. Increased reflectivity decreases both absorption and emission of radiation. Foil may have a non-stick coating on only one side. The reflectivity
The reflectance of the surface of a material is its effectiveness in Reflection (physics), reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the respon ...
of bright aluminium foil is 88% while dull embossed foil is about 80%.
Uses
Aluminum foil is widely sold into the consumer
A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. T ...
market, often in rolls of width and several metres in length.
Electromagnetic shielding
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 decibel
The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a po ...
s (dB) (less than 10−8 = 0.00000001 of the power gets through).
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 per cent 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.
Cooking
Aluminium foil is also used for barbecuing
Barbecue or barbeque (informally BBQ in the UK, US, and Canada, barbie in Australia and braai in South Africa) is a term used with significant regional and national variations to describe various cooking methods that use live fire and smoke ...
delicate foods.
As is the case with all metallic items, aluminium foil reacts to being placed in a microwave oven
A microwave oven (commonly referred to as a microwave) is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to rotate and produce t ...
. This is because of the electromagnetic field
An electromagnetic field (also EM field or EMF) is a classical (i.e. non-quantum) field produced by (stationary or moving) electric charges. It is the field described by classical electrodynamics (a classical field theory) and is the classical c ...
s of the microwaves inducing electric currents in the foil and high potentials
Potential generally refers to a currently unrealized ability, in a wide variety of fields from physics to the social sciences.
Mathematics and physics
* Scalar potential, a scalar field whose gradient is a given vector field
* Vector potential ...
at the sharp points of the foil sheet; if the potential is sufficiently high, it will cause electric arc
An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...
ing 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
The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
tube from microwave energy reflection, and aluminium packages designed for microwave heating are available.
Environmental issues
Some aluminium foil products can be recycled
Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...
at around 5% of the original energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
cost.
See also
* Tin foil hat
A tin foil hat is a hat made from one or more sheets of aluminium foil (commonly called "tin foil" in the United States and New Zealand), or a piece of conventional headgear lined with foil, often worn in the belief or hope that it shields the Hu ...
* 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 ...
References
External links
European Aluminium Foil Association
Aluminium Association (USA)
from ''How Products Are Made,'' vol. 1, Thomson Gale (2005).
How It's Made: Aluminium Foil
- HowItsMadeEpisodes channel on YouTube.
{{Portal bar, Chemistry
Food preparation utensils
Aluminium
Packaging materials
Metalworking
Swiss inventions
Aluminum objects