Aluminium is used for packaging as it is highly malleable: it can be easily converted to thin sheets and folded, rolled or packed. Aluminium foil acts as a total barrier to light and oxygen (which cause fats to oxidise or become rancid), odours and flavours, moistness, and germs, and so it is used broadly in food and pharmaceutical packaging, including long-life packs (aseptic packaging) for drinks and dairy goods, which allows storing without refrigeration. Aluminium foil containers and trays are used to bake pies and to pack takeaway meals, ready snacks and long life pet foods.

Aluminium foil is widely sold into the consumer market, often in rolls of 500 mm (20 in) width and several metres in length. It is used for wrapping food in order to preserve it, for example, when storing leftover food in a refrigerator (where it serves the additional purpose of preventing odour exchange), when taking sandwiches on a journey, or when selling some kinds of take-away or fast food. Tex-Mex restaurants in the United States, for example, typically provide take-away burritos wrapped in aluminium foil.

Aluminum foil is widely used for radiation shield (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.

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).

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 electric field is attenuated by more than 80 decibels (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.[13] For effective shielding from a magnetic field, the shield should be several skin depths thick. Aluminum foil is about 1 mil (25 µm); a thickness of 10 mils (250 µm) (ten times thicker) offers less than 1 dB of shielding at 1 kHz, about 8 dB at 10 kHz, and about 25 dB at 100 kHz.

Aluminium foil is also used for barbecuing more delicate foods, such as mushrooms and vegetables. Using this method, sometimes called a hobo pack, food is wrapped in foil, then placed on the grill, preventing loss of moisture that may result in a less appealing texture.

As is the case 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 potentials at the sharp points of the foil sheet; if the potential is sufficiently high, it will cause electric arcing 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.

Heavier foils made of aluminium are used for art, decoration, and crafts, especially in bright metallic colours. Metallic aluminium, normally silvery in colour, can be made to take on other colours through anodisation. Anodising creates an oxide layer on the aluminium surface that can accept coloured dyes or metallic salts, depending on the process used. In this way, aluminium is used to create an inexpensive gold foil that actually contains no gold, and many other bright metallic colours. These foils are sometimes used in distinctive packaging.

Foil is used by organic/petroleum geochemists for protecting rock samples taken from the fields and in the labs where the sample is subject to biomarker analysis. While plastic or cloth bags are normally used for a geological sampling exercise, cloth bags are permeable and may allow organic solvents or oils (such as oils imparted from the skin) to taint the sample, and traces of the plastics from plastic bags may also taint the sample. Foil provides a seal to the ingress of organic solvents and does not taint the sample. Foil is also used extensively in geochemical laboratories to provide a barrier for the geochemist, and for sample storage.

The material used in many ribbon microphones is aluminium leaf, or “imitation silver leaf”, as it is sometimes called. This is pure aluminium and is around 0.6 to 2.0 micrometres thick. It is virtually the same material that the BBC used on Coles ribbons, with the exception that they also hand beat the leaf even thinner. They did this by sandwiching the ribbon between toilet paper and beating with a ball-peen hammer. This “cold forges” the leaf. The aluminium leaf was then annealed for an hour in an oven to restore flexibility. Corrugations must also be imparted into the ribbon: Coles used 25 per inch (1 mm cycle). RCA 44BX has 19 corrugations per inch (0.7 mm cycle) and is around 50 mm (2.0 in) long; RCA 77 has 13 corrugations per inch (0.5 mm cycle). RCA ribbon material is around 1 to 1.5 micrometres (0.00005 inch) thick. The new Nady ribbon plus AEA both state that they use 2 micrometre aluminium ribbon in their microphones