fólií

Fólií, or foil, refers to a thin sheet of material, typically metal, but also plastic or composite, used to wrap, shield, or insulate objects. Foils are chosen for their thinness, pliability, and barrier properties.

Metal foils include aluminium, copper, tin, and gold. The most common household foil is aluminium. Plastic foils or films—such as those made from PET, PVC, or polyethylene—are widely used for packaging and technical applications. Foil thickness ranges from roughly 6 to several hundred micrometers, with typical consumer aluminium foil around 8–25 µm.

Production methods include rolling for metal foils, cold rolling to reach thinness, followed by annealing to restore ductility. Plastic foils are produced by extrusion or casting. Foils may be metallized (a thin metal layer on a polymer film) or laminated with other layers to improve properties such as barrier resistance.

Applications are broad. In packaging, foils protect foods against moisture, gases, and light. In insulation, foil-faced materials reduce heat transfer. In electronics, copper foil serves as conductive layers in printed circuit boards. Foils are also used in solar reflectors, insulation products, and decorative arts.

Historically, tin foil was used in the 18th and 19th centuries for wrapping, but modern packaging relies on aluminium foil and advanced laminates developed in the 20th century. Aluminium foil is widely recyclable, though recycling streams vary; plastic foils require separate handling and can pose environmental challenges.