Buyers new to reflective materials often ask for “aluminium foil” when they mean metallised film, or the other way round. The two look alike on a roll and both reflect light and heat, but they are different materials with different strengths. Here is how to tell which one your product needs.
What each one is
Metallised PET is polyester film with an extremely thin layer of aluminium deposited on it in a vacuum chamber. The aluminium layer is a small fraction of a micron thick; the film is what you are actually handling. It is often called mylar film after an old trade name.
Aluminium foil laminate is solid rolled aluminium foil, typically several microns thick, bonded to a carrier such as polyethylene, polyester, woven scrim or kraft paper. The foil is a real metal layer; the carrier stops it tearing.
Where metallised film wins
- Cost and weight. Far less aluminium, so cheaper and lighter per square metre.
- Flexibility. Folds and creases without cracking, which suits tents, liners and anything that is packed flat.
- Appearance. Can be made mirror-bright or matte, embossed with a pattern, and metallised on both sides.
- Printability. The polyester back accepts printing and adhesives cleanly.
Where foil laminate wins
- Emissivity. Solid foil has a lower emissivity than a metallised surface, which means it reflects a higher share of radiant heat. For insulation that is the number that matters.
- Durability of the reflective layer. A metallised layer can abrade or oxidise over years; solid foil is more robust, especially outdoors or on a roof.
- Barrier. Foil is a near-perfect barrier to water vapour and oxygen. Metallised film is good, foil is better, which is why food and pharmaceutical packaging uses foil.
- Temperature. Foil on a polyester or scrim carrier tolerates heat that would damage a metallised film’s coating.
How to choose
If the material’s job is to reflect light evenly, be folded and look good, choose metallised film. If its job is to reflect heat for years, block moisture or survive high temperature, choose a foil laminate. Many finished products use both: a metallised film face for appearance and a foil layer inside for barrier or emissivity.
We supply both and can laminate either to scrim, foam, bubble or paper. Describe the end use and we will recommend the construction and send swatches of each.