Window film technology
Metallised Film
Metallised film uses a thin layer of aluminium or other metals to reflect heat; it performs well but can interfere with mobile, GPS and ERP signals.
Metallised window films contain a vapour-deposited or sputtered metallic layer (commonly aluminium, sometimes nickel or titanium) bonded between PET layers. Metals reflect a broad band of solar energy, giving good Total Solar Energy Rejection — historically the best performance available before ceramics matured.
The trade-off is signal attenuation. Aluminium-based films create a Faraday-cage effect that weakens mobile signal, GPS lock and ERP transponder reads. On a Singapore vehicle with In-Vehicle Unit (IU) on the windshield, that interference can cause failed ERP deductions.
Modern installations almost always favour ceramic or nano-ceramic over metallised film for cars. Metallised films still have a niche in architectural applications where signal interference is not a concern.