This question keeps emerging on sorts of Q&A platforms, which
demonstrates people’s eagerness to have an answer. Here we hope to offer what
you just need.
Before getting to the answer, we need to clarify the concept of “rust” first. Rust is a chemical process during which metals get oxidized after being exposed to the air that is full of oxygen, yet this is not enough, for the word usually indicates a state of “decay” of a metal on the surface. Take iron for example, dark brown powder covers the surface of an oxidized iron and falls off under slight exterior forces like wind, rubbing or vibration. This means that the outer layer of iron is ripped away to form ferrous oxide, and because it is porous, oxygen can continue to penetrate to the iron, creating more rust. Eventually, the entire iron object will be converted to rust. Most metals rust in the same way, except for rare ones like aluminium whose oxide is a solid layer attached firmly onto the surface of an aluminium piece. Therefore, aluminium oxide can not be called something like decay in a strict point of view.
But if you mean “oxidize” by “rust”, then aluminium foil is likely to get rust soon after being placed in the air. Some metals are more reactive than others and Aluminum is far more energetic to oxidize than iron. The roll of aluminum foil you get in the store is already rusted before you use it.
So why does it still look shiny? Aluminum forms aluminum oxide. This is an
extremely hard material that forms a layer on the surface that is only a few
molecules thick. It then prevents more oxygen from getting to the pure aluminum
below the oxide layer. Thus if you mean “decay” by “rust”, then aluminum does
not rust. It only get oxidized. Magically, the oxidizing process makes it more
“corrosion resistant” in a way.
Because of its excellent characteristics, aluminum foil is widely used in food, beverage, cigarettes, pharmaceuticals, photographic substrates, household articles, etc. It is usually used as packaging materials; electrolytic capacitor materials; insulation materials for buildings, vehicles, ships, houses, etc. It can also be used as decorative gold and silver wire, wallpaper and decorative trademarks of various stationery, printing products and light industrial products. In all the above applications, the most effective way to develop the performance of aluminium foil is as packaging material. Aluminum foil is a soft metal film, which not only has the advantages of moisture-proof, air-tight, shading, wear-resistant, fragrance-preserving, non-toxic and tasteless, but also because of its elegant silver-white luster, easy to process beautiful patterns and patterns of various colors, so it is more likely to be favored by people’s aluminum foil tape.
With the improvement of people’s living standards and the development of
tourism, the demand for beer, soda and other beverages and canned food is
increasing day by day, which requires modern packaging and decoration to
facilitate competition in the international market. In order to meet the market
requirements, people have developed good shielding plastic film and spray foil
packaging materials, but their comprehensive properties are not as good as
coating and lamination processing can be made up and improved.
After aluminum foil deflector beanie is compounded with plastics and paper,
the shielding property of aluminium foil is integrated with the strength of
paper and the thermal sealing property of plastics, which further improves the
shielding properties of water vapor, air, ultraviolet ray and bacteria, which
are necessary for packaging materials, and greatly expands the application
market of aluminium foil. Aluminum foil manufacturer is well protected because
of its full isolation from light, humidity and air outside. Especially for the
packaging of cooked food, the use of this composite aluminum foil material can
ensure that food does not deteriorate for at least one year. Moreover, heating
and unpacking are very convenient and popular with consumers.
Therefore, it can be said that aluminium foil is a kind of perfect packaging
material with many excellent properties, which fully shows its broad application
prospects in many fields. In order to improve rolling efficiency and quality of
heavy duty aluminum foil products, modern aluminium foil rolling mills are
developing in four directions: large coil, wide width, high speed and
automation. The roll width of contemporary aluminium foil mill has reached more
than 2200 mm, the rolling speed has reached more than 2000 m/min, and the coil
weight has reached more than 20 t. The automation level of the rolling mill is
also greatly improved. AGC is generally installed, and AFC is mostly installed.
Aluminum foil industry is facing a period of rapid development.
Aluminum foil is a kind of very thin aluminium coil, strip or sheet obtained by rolling aluminium and aluminium alloy strip coil. Aluminum and aluminium alloy sheets and strips with thickness less than 0.2mm are generally referred to as aluminium foils.
Classification of aluminium foil:
According to the shape, it can be divided into rolled and flaky aluminum
foil. Aluminum foil products are mostly supplied in rolls, and only a few
handicraft packaging users use aluminum foil sheet.
According to the thickness, it can be divided into three kinds: thick
aluminum foil, single zero aluminum foil and double zero aluminum foil. Thick
foil is 0.1-0.2mm thick foil, single zero foil is 0.01mm thick foil and less
than 0.1mm thick foil, double zero foil is thickness of the decimal point after
two zero foil.
(3) According to the state, the main foils are hard aluminum foil, soft
aluminum foil, semi-hard aluminum foil, one quarter of hard foil and three
quarters of hard foil.
(4) According to the surface state, it can be divided into single-sided
aluminum foil and double-sided aluminum foil.
(5) According to the use, it can be divided into packaging aluminum foil,
commodity aluminum foil, electrical equipment aluminum foil and construction
Properties of aluminium foil:
Aluminum foil has thin and light material, high specific strength, good
gloss, high thermal conductivity and conductivity, high moisture-proof,
non-toxic, tasteless, good optical rotation, thermal insulation and good
The shielding effectiveness of aluminium foil depends upon the type of incident field (electric, magnetic, or plane wave), the thickness of the foil, and the frequency (which determines the skin depth). Shielding effectiveness is usually broken down into a reflection loss (the energy bounces off the shield rather than penetrates it) and an absorption loss (the energy is dissipated within the shield).
Aluminum foil for electromagnetic shielding:
Excellent High Frequency RF Shielding characteristics
Effective barrier against Low Frequency AC Electric Fields when grounded.
Can be used as a Vapor Barrier – not breathable
Heavy Duty / Tear Proof
Flexible and light weight which allows for an easy installation
Safe to handle and non-toxic
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 decibels
(dB) — however actual energy absorption is minimal: the remaining
high-frequency rf energy is almost perfectly reflected from uniform flat
aluminium surface, and thus, reflected signal may continue to propagate
internally, and if holes or passages of suitable geometry exist in the shield,
signal propagation may continue out through those, the aluminium being good
material for implementation of a microwave-frequency waveguide.
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.For effective shielding from a magnetic field, the shield should
be several skin depths thick. Aluminium foil is about 1 mil (25 μm); a thickness
of 10 mils (250 μm) offers less than 1 dB of shielding at 1 kHz, about 8 dB at
10 kHz, and about 25 dB at 100 kHz. At these frequencies a ferromagnetic
material such as mild steel is much more effective, due to different and
complementary electromagnetic permeability properties, and common practical
shielding implementations utilise both an inner high-frequency reflective
material such as aluminium, preferably bonded (via annealing or electroplating,
done to avoid capacitance between separated layers), to a more substantial
structural ferromagnetic shell, usually mild steel (in specialized applications,
more expensive, less structurally useful and less workable materials may be
preferred.) Despite the relative low mass density of aluminium, this design is
usually both lighter and more effective than an equivalently absorptive design
utilizing aluminium alone.
Aluminum foil is widely used in many sectors of national economy and people’s daily life because of its light weight, good sealing and encapsulation, but it is mainly used in packaging, electromechanical and construction fields. Aluminum foil can be classified according to its thickness, shape, state or material.
Aluminum foil can be divided into thick aluminium foil, single zero aluminium foil and double zero aluminium foil according to thickness difference.
Thick foil: Aluminum foil with thickness of 0.1-0.2 mm.
(2) Single zero foil: aluminium foil with thickness of 0.0lmm and less than
(3) Double zero foil: The so-called double zero foil is the aluminium foil
whose thickness is less than 0.0075 mm, which has two zero foils after decimal
point when its thickness is measured in mm. When expressed in English, thick
aluminium foil is called “heavy gauge aluminium foil”, single zero aluminium
foil is called “medium gauge foil” and double zero foil is called “light gauge
foil”. Aluminum foil with thickness less than 40 LTM is sometimes called light
gauge foil in foreign countries, while aluminum foil with thickness greater than
40 BTM is collectively called heavy gauge foil.
Aluminum foil can be divided into aluminium foil roll and aluminium sheet
foil according to its shape. Aluminum foil deep-processed wool is mostly
supplied in rolls. Only a few handicraft packaging occasions use aluminium sheet
Aluminum foil can be divided into hard aluminium foil, semi-hard aluminium
foil and soft aluminium foil according to its state.
(1) Hard foil: Aluminum foil without softening treatment (annealing) after
rolling and without degreasing treatment, the surface is marked with residual
Shantou. Therefore, the hard aluminium foil must be degreased before printing,
bonding and coating. If it is used for forming, it can be used directly.
(2) Semi-hard aluminium foil: Aluminum foil whose hardness (or strength) is
between hard foil and soft foil is usually used for forming.
(3) Soft foil: Aluminum foil softened after full annealing after rolling,
with soft material and no residual oil on its surface. At present, soft foil is
used in most applications, such as packaging, composite, electrical materials
and so on.
Aluminum foil can be divided into one-sided and two-sided according to its
(1) One-sided glossy aluminium foil: double rolled aluminium foil, after
coiling, one side is bright, – face is black, such aluminium foil is called
one-sided glossy aluminium foil. The thickness of one-sided aluminium foil
usually does not exceed o.025mm.
(2) Two-sided aluminium foil: single rolled aluminium foil, two drawings
contacted with rolls. The two sides of aluminium foil can be divided into mirror
two-sided aluminium foil and common two-sided aluminium foil because of the
different surface roughness of rolls. The thickness of dihedral aluminium foil
is generally not less than 0.01mm.
Aluminum foil can be divided into plain aluminium foil, embossed aluminium
foil, composite aluminium foil, coated aluminium foil, colored aluminium foil
and printed aluminium foil according to the added state.
Plain aluminium foil: Aluminum foil rolled without any other processing, also
known as light foil.
(2) Embossed aluminium foil: Aluminum foil with various patterns on the
(3) Composite aluminium foil: Aluminum foil and paper, plastic film,
cardboard bonded together to form a composite aluminum foil. Coated foil:
Aluminum foil coated with various resins or varnishes.
Coloured aluminium foil: The surface is coated with a single color of
Printing aluminium foil: Aluminum foil, which forms various patterns,
patterns, words or pictures on the surface by printing, can be a color, up to 12
Aluminum foil pipe,provides excellent insulation: Reflects up to 97% of
radiant energy in addition to resisting other types of heat transfer from
conduction, convection and radiation. The two side anodized aluminum foil forms
an effective barrier against moisture, air currents and vapors.
Application: Electromagnetic shielding, refrigetors, air conditioners,cars,
subways, household decoration and other appliances.
Generally, the thickness of aluminum foil for Packaging is between 0.03 mm and 0.1 mm. This is because the packaged article is sufficiently isolated from the outside light, moisture, gas, etc., so that the package is well protected. Especially for the packaging of retort foods, the use of this composite aluminum foil material can at least guarantee that the food does not deteriorate for more than one year. Moreover, heating and unpacking are very convenient and are very popular among consumers.
This is related to the characteristics of aluminum foil.
Features of packaged aluminum foil:
The aluminum foil has a clean, hygienic and shiny appearance. It can be
integrated with many other packaging materials, and the surface of the aluminum
foil is better than other materials. In addition, the aluminum foil has the
(1) The surface of the aluminum foil is extremely clean and hygienic, and no
bacteria or microorganisms can grow on its surface.
(2) Aluminum foil is a non-toxic packaging material that can be in direct
contact with food without any concern that may endanger human health.
(3) Aluminum foil is an odorless and odorless packaging material that does
not impart any odor to the packaged food.
(4) If the aluminum foil itself is not volatile, it itself and the packaged
food will never dry or shrink.
(5) There is no oil penetration of the aluminum foil at high temperatures or
at low temperatures.
(6) Aluminum foil is an opaque packaging material, so it is a good packaging
material for products exposed to sunlight, such as margarine.
(7) Aluminum foil has good plasticity, so it can be used to package products
of various shapes. It can also be used to create containers of various
(8) The aluminum foil has a large hardness and a large tensile strength, but
its tear strength is small, so that it is easily torn.
(9) The aluminum foil itself cannot be heat-sealed and must be coated with a
heat-sensitive material such as pe to be heat-sealed.
(10) When aluminum foil is in contact with other heavy metals or heavy
metals, there may be adverse reactions.
Aluminum foil rolls and sheets come in a variety of thicknesses, widths, and lengths. Manufacturers often make the width and length of the foil roll easy to find, but the thickness of the foil is often not advertised.
Household use standard duty aluminium foil rolls are often between 75 ft. and
250 ft. long, offered in a variety of widths. The majority of foil rolls labeled
as “Standard Duty” are between .0004 thick and .0007 thick. Which at best is
slightly over or one half of a mil in thickness.
Some users prefer a thin pliable foil for a variety of home use and
commercial needs. Most standard duty or economy foils are often much more
affordable than heavy duty or extra heavy duty foils. Some users do not prefer
the standard duty foils because of easy tearing and burning when baking.
Heavy Duty Aluminum Foil – Many cooks use it for baking, grilling, and
storage. Most Aluminum foil rolls labeled “Heavy Duty” are between .0008 thick
and .001 thick.
Extra Heavy Duty Foil – A harder thickness to find, but some manufacturers do
produce extra heavy duty foil. It provides excellent tear resistance and works
well with everything the heavy duty and the standard foil is used for. Most
aluminum foil labeled “Extra Heavy Duty” are between .0011 thick and .0016
Is aluminum foil recyclable?Aluminum is one of the highest-value materials
you can recycle, and it can be reprocessed into new aluminum in just 60
days.Aluminum is used for more than foil aluminum, of course. Cans, cars, even
my laptop is made of aluminum. Aluminum compounds are used as catalysts in
chemical reactions to make elemental sulfur and various hydrocarbons, which can
be starting materials for making plastics, medicines, fertilizers, rubber
products and more.
Aluminum foil thickness is made from the same material as soda cans (aluminum), but since it’s most often contaminated with food waste or combined with plastic (like with yogurt tops), there’s no guarantee you can recycle it with your aluminum cans.
Aluminum Foil Recycling Preparation,How to recycle aluminum foil?
You want to make sure that aluminum foil is as clean as possible before
recycling. While burns and holes won’t affect the recycling market, you’ll want
to remove any meats or sauces from the foil.
If you’re recycling aluminum foil that you bought and used for storage,
separate the foil from the paperboard box and corrugated tube before
If foil is combined with other materials (such as in drink boxes, candy
wrappers and yogurt tops) and can’t be separated, you’ll want to throw it away.
Foil mixed with other materials is considered recycling contamination.
Combine all sheets of thick aluminum foil into one ball. This will keep the
material easily separated from other products, and also prevent it from blowing
away (aluminum foil is a very light material).
Your first step is to make sure your aluminum foil is devoid of food waste.
You can rinse off small bits of food, like cookie crumbs and fruit or vegetable
juice. The foil may discolor if you use hot water, but that is totally normal.
If the foil is very heavily soiled with oily or greasy foods like meat,
frosting, gravy or butter, it will need to go in the trash.
Your second step is to determine if your curbside recycling program accepts
aluminum foil. you will need to find another way to recycle your aluminum foil.
Before placing any foil in your recycling bin, crumple it into a ball so it will
not get torn or stuck in the recycling machinery. Do not take each individual
piece and ball it up so that you have several tiny spheres. Instead, save up
your aluminum foil and make a ball that is at least two inches in diameter. And
again, make sure it is clean before you place it in your recycling bin. Keep in
mind that several food products come with aluminum foil pan attached. Many
yogurt containers have aluminum foil over the lids. K-cups also have aluminum
foil lids. If you can recycle sheets of aluminum foil, chances are high you can
recycle these items as well. Check with your recycling company to see if they
can take other types of clean aluminum food storage products, like pie pans and
turkey roasters, too. I reuse my clean aluminum foil whenever possible.
Aluminum foil provides a complete barrier to light, oxygen, moisture and bacteria. For this reason, foil is used extensively in food and pharmaceutical packaging. It is also used to make aseptic packaging that enables storage of perishable goods without refrigeration. (more…)