Window film is a thin film or laminate that can be installed to the interior of glass surfaces in automobiles, boats, homes and buildings. It is usually made from polyesterdue to its clarity, tensile strength, dimensional stability; and ability to accept a variety of surface-applied or embedded treatments.
Window film can be generically described by the components it contains for performance and/or aesthetics; i.e. dyed, metallized, ceramic – or by its intended use. Uses can be divided into automotive/marine, where surfaces are often curved, and architectural where flat glass is usual. Window film is usually applied by professional service companies, but there are also kits widely available.
Security films are applied to glass, so when the glass is broken, it holds together, preventing dangerous shards from flying about, or to make it more difficult for an intruder to gain entry. Normally applied to commercial glass, these films are made of heavy-gauge plastic and are intended to maintain the integrity of glass when subject to heavy impact such as a crash. The most robust security films are capable of preventing fragmentation and the production of hazardous glass shards from forces such as bomb blasts. Some companies have even experimented with bullet ballistics and multiple layers of security film. Another key application for security window films (safety window films) is on large areas of “flat glass” such as storefront windows, sliding glass doors, and larger windows that are prone to hurricane damage. These security films, if applied properly, can also provide protection for vehicles. These security films are often tinted and can be up to 400 micrometers (µm) thick, compared to less than 50 µm for ordinary tint films. If anchored correctly, they can also provide protection for architectural glazing in the event of an explosion. A layer of film (of 100 µm thickness or greater) can prevent the ejection of spall when a projectile impacts on its surface, which otherwise creates small dagger-like shards of glass that can cause injury.
Protection from UV light can be accomplished by film that addresses only the UV spectrum. As UV is one of the main sources of fading, it can extend the life of fixtures and fittings. Basic colorless clear films reject (absorbs) some UV radiation up to 380 nm, and depending on the manufacturer, UV inhibitors are added to the polyester, with specialist films offering protection to 400 nm. Tinted films are needed for protection to 500 nm.
Window films filter out nearly all of UV rays to 380 nm, reducing the main factor in fading. However, more factors such as solar heat, visible light, humidity, and chemical vapors also play into fading. Therefore, the greatest protection from fading is offered by tinted or metaled window films that stop large levels of heat and visible light, in addition to UV.