Window film
From Wikipedia, the free encyclopedia
Window film, also called window tint, is transparent plastic film or metallic laminate which is applied to glass windows. It is available in many different compositions with varying effects on the optical and mechanical properties of the underlying glass. Because window film is applied to finished glass it is easier to install and less costly than chemically altered specialty glass.
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[edit] Primary properties
Heat rejection films are normally applied to the interior of flat glass windows to reduce the amount of infrared, visible, and UV radiation entering windows. Such films are either dyed or metalized (which can be transparent to visible light) to convert incoming solar radiation to infrared radiation, which is then rejected back through the glass to the exterior. They usually cost 10-15% more than regular windows but can reduce energy loss by as much as 30-50%.[1] [2] To keep the sun's heat out of the house, the Low-E coating should be applied to the outside pane of glazed windows. If the windows are designed to provide heat energy in the winter and keep heat inside the house (typical of cold climates), the Low-E coating should be applied to the inside pane of glazed windows.[3] Such films also reduce the amount of visible and ultraviolet light entering a window, and are often applied to reduce fading of the contents of a room. Silvered film may also be employed to the same end.
Security films are applied to prevent glass from shattering. Typically 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. The most robust security films are capable of preventing fragmentation and the production of hazardous glass shards from forces up to and including bomb blasts.[4] These security films ( if applied properly) can also provide protection for vehicles [5] video available at [6] . These security films are often tinted and can be up to 400 microns thick, compared to less than 50 microns for ordinary tint films. If anchored correctly they can also provide protection for buildings against bomb blast [7] Laminated glass also benefits from being fitted with security film as laminated glass ' spalls ' on impact creating small dagger-like shards of glass that can cause injury [8]
Graphic design films are generally colored vinyl or frosted. Frosted finish films closely resemble sandblasted or acid-etched glass, while vinyl films are available in a range of colors. Both types of films are commonly used in commercial applications.
Privacy films reduce visibility through the glass. Privacy film for flat-glass commercial and residential applications may be silvered, offering an unimpeded view from the low-light side but virtually no view from the high-light side. It may also be frosted, rendering the window translucent but not transparent. Privacy films for automobiles are available in gradients of darkness, with the darker tints commonly known as "limo tint".
Correctly applied mirror film can create one way mirrors as seen on the UK reality program ' Big Brother ' [9]
Other benefits includes protection for passengers in the rear, protection from harmful Ultra Violet (UV) rays, more effective and practical than stick-on blinds, essential cooling for pets, greater privacy, reduces visibility of valuables, reduces glare and reflection on LCDscreens and can offer protection for those suffering from extreme photo-sensitive conditions or skin sensitivity such as lupus .
Films are available with almost any conceivable combination of the above properties.
[edit] Certification & Standards
The thicker window films known as safety and security window film are designed to perform under extreme conditions, and as such there are soecific standard criteria these films should meet, such as American standards ANSI Z.97, CPSC 16 CFR 1201, Cat II (400 ft-lb), and the British Standards BS 6206 (Class A, B & C). The European Committee for Standardization offer the EN12600 standard Classification of Resistance of Glazing to Impact. Often, building codes dictate that a film must have a report verifiying that it has met at least one of these standards.
Solar window film is usually subject to less critical testing. However, standards are in place to maintain a level of quality in the industry. The ANSI Standards ASTM E903 and ASTM D1044-93 relate to the Solar/UV transmission properties, and abrasion resistance respectively. The larger window film manufacturers use these standards to guarantee the quality of their raw materials and finished products.
[edit] Regulations for automotive use
Automobile window tinting, by its nature, reduces the visible light transmittance through a car's windows. This can be problematic at night, when motorists must be able to see through the windows of other vehicles in order to spot hazards which would otherwise be obstructed. Police officers also want to be able to identify the passengers in a vehicle.
In many jurisdictions, there are laws to ensure darkness of films do not present a danger to motorists.
In the United States, the federal Department of Transportation specifies a minimum of 70% visible light transmission (VLT) for window tinting on the windshield and the windows to the immediate left and right of the driver. The DoT does not specify any VLT requirements for any other windows [10]. Individual states can pass laws that go further than the requirements set forth by the DoT. The DoT regulates commercial vehicles, not private vehicles. Links to state laws that govern tinting on private vehicles can be found in the external links section. Private vehicles may have tint on the windows to the immediate left and right of the driver as dark as 20% VLT, depending on the state.
In Canada, automobile tinting laws are set at the province level.
In the UK regulations dictate that all front windows in front of the B post can have no less than 70% light transmission [11] and windscreens are only allowed tinting outside the sweep of the windscreen wipers to a maximum of 6 inches from the top of the windscreen downwards of the drivers vision is in no way obscured, sometimes known as a ' top tint '
[edit] Installation
Window films are usually professionally installed; however, most films require few specialized tools to install and may be installed by consumers. Incorrectly installed films may bubble or peel.
It is especially difficult to install tint film on auto glass with curvature, for example, in the case of rear windows of cars, because of the care required in cutting and sizing the film. Auto tint is best installed by professionals; without the proper tools and techniques, amateur filming is prone to bubbling and separation from the glass.
Window film is typically installed after surfaces are throughly cleaned and wiped, typically using a commercial cleaner and a scraper blade, and then a simple soap solution is squirted on the glass before the film layer is mounted.
[edit] Removal
Window tint and the adhesive that adheres it to the glass is difficult to remove. While it is generally best done by experts, the consumer can remove it with appropriate materials and care. The process involves heating the film with a hair dryer or a steamer to soften the adhesive, pulling the film off in small sections, and dissolving the glue with a strong ammonia solution which may then be wiped off. Some professional tinting companies remove the glass for a perfect finish making removal of the film very difficult for the novice once it has been re installed.
[edit] External links
- Canadian auto tinting laws by Province
- European auto tinting laws by Country (PDF)
- U.S. auto tinting laws by State
- International Window Film Association
- Window Film Association of Australia and New Zealand
- Installation instructions, American tinting laws and tinter's forum
- Performance specs and color samples for Window Film Brands
- US Department Of Energy Consumer Guide
- Window Tinting Guide
