Metallized films (or metallised 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 decorative purposes and food packaging, and also for speciality applications including insulation and electronics.
Metallised films were first used for decorative purposes as Christmas tinsel, and continue to be used for items such as wrappers and ribbons. The metallic helium filled novelty balloons given as gifts are made of metallised BoPET and often called Mylar balloons commercially.
Metallised films are used as a susceptor for cooking in microwave ovens. An example is a microwave popcorn bag. Many food items are also packaged using metallised films for appearance only, as these produce a package with greater sparkle when compared to competing products that use printed paper or polymer films.