Window tinting

Window film is a generic term for film applied to glazing; for automotive applications it may be known as window tint. There are many types of window film available in the market for a wide variety of uses from energy savings and solar heat reduction to UV protection, privacy to safety and security, decorative applications to heat retention. Two broad categories of window film exist: polyester based products for all types of applications and vinyl products that are almostly exclusively used for aesthetics and / or manifestation purposes within buildings.

[edit] Primary properties

The colorful film on these windows gives the building a unique appearance while providing privacy and insulation from the sun.

Solar control films are normally applied to the interior of flat glass windows to reduce the amount of infrared, visible light, and ultraviolet (UV) radiation entering interior spaces through windows. Such films may be dyed, metallized, sputtered or a combination of these and are usually transparent to visible light. Solar control films reflect and absorb incoming solar radiation. Absorbed solar radiation is re-radiated by the filmed glazing to both interior and exterior spaces; the proportions radiated to these spaces depend upon the local environmental conditions. The total solar energy rejected to the exterior is thus the sum of the reflected solar energy plus the absorbed energy that is radiated externally. The most effective solar control window films are those with high solar energy reflection. More recently, exterior grade products have been developed to provide installation and performance options depending upon glazing type, access to interior glazed surfaces and end-use requirements. Solar control films, by rejecting solar energy to the exterior, reduce loading on air conditioning systems, hence reducing energy use and carbon emissions; savings of up to 10 % of a building's total energy use with payback times of less than 3 years are possible.

Insulation or Low E films have a low emissivity surface (hence Low E). This surface is a low emitter of radiation and reduces the emission of radiation through the glazing. In winter, the coating works by reducing heat loss to the exterior; in summer, the coating works by reducing transfer of energy by radiation from the hotter exterior environment to the interior. All current Low E films are also solar control films giving rise to the occasional use of the 'all season' term. Insulation films can reduce energy loss from interior spaces by as much as 30 percent."^[1] for single glazing; the reduction in energy loss for other glazing systems depends upon the construction of the glazing but may be as high as 17 %.

Safety and security films (also known as Anti-Shatter Film) are applied to glass with the primary benefit of reducing the risk of injury from cutting and piercing; reducing damage to property is a secondary but important benefit. These films are made of heavy-gauge plastic and are intended to retain broken glass fragments when subject to impact. Safety and security films are capable of preventing fragmentation and the production of hazardous glass shards from forces such as bomb blasts; in the 1990's 100 micron (0.004 inch or 0.100 mm) thick film was extensively used for blast protection but the higher performance offerred by thicker films has reduced their use; typical blast protection films used in the late 1990's and since are 175-200 microns, with thicker products being used for special applications. These films can be up to 400 micrometers (µm) thick, compared to less than 50 µm for ordinary tint films. Some companies have even experimented with bullet ballistics of multiple layers of security film.^[2]. Safety and security films can also provide protection for vehicles.^[3] and may also be solar control films with tints, metallic coatings, etc. as for standard solar control products.

Normally, window films are applied with a small visible gap between the film edge and frame margin. In certain circumstances, especially for blast protectiona and overhead tempered glass, anchoring systems may be used to enhance the performance of safety and security films^[3]. The objective of these systems is to secure the film perimeter to the frame. This may be achieved by a flexible tape that adheres to the film and to the frame; the tape may have semi-rigid sections that adhere to the film and frame with a flexible section joininng the rigid sections. Mechanically fixed systems in effect both secure the film with an additional frame as well as increasing the bite depth of the glazing in the frame. Safety and security film (of 100 µm thickness or greater) can also prevent the ejection of spall, for example from laminated glass; spalling typically occurs when a projectile impacts on a glass surface, creating small dagger-like shards of glass that can cause injury.

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.

Other benefits include protection for passengers in the rear, protection from UV rays (which have some harmful effects), cooling for pets, greater privacy, reduced chance of theft (because valuables are less visible), reduced glare and reflection on liquid crystal display (LCD) screens, and protection for those who have conditions involving photosensitivity or skin sensitivity, such as lupus (SLE). Window film is also considered more effective and practical than stick-on blinds.

Frosted window film, stained glass window film, and privacy window film can now be purchased online for residential or commercial applications at Glass Decor and More.Glass Decor and More

[edit] Unintended Features

Under certain conditions, window film will exhibit iridescence. This phenomenon usually occurs at night, when the source of illumination within a building is fluorescent lighting.

The amount of iridescence may vary from almost imperceptible, to very visible and most frequently occurs when the film is constructed using one or more layers of sputtered metal. It can however occur in non-reflective films as well.

When iridescence does occur in window film, the only way to stop it is to prevent the fluorescent light from illuminating the film.

[edit] Certification and standards

The thicker window films known as safety and security window film are designed to perform under extreme conditions, and as such there are specific 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). CEN, the Committée Européenne de Normalisation has developed the EN 12600 standard "Glass in building - Pendulum - Impact test method and classification for flat glass"; most European countries have ratified this European Norm as a national standard to replace local impact test methods.. Often, building codes and regulations dictate that a film must have a test report verifying that it has met at least one of these standards.

Solar control 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

Window tint on a convertible in America. Tint on the front window is lighter than on the back window because of window tint laws.

Automobile window tinting reduces the visible light transmission (VLT) through car 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 also may 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:

Tint Limits by U.S. state:

^{[citation needed]}

(Lower number is less light transmittance, thus darker tint)

• In the United States, the Federal Motor Carrier Safety Administration, an administration within the federal Department of Transportation (DOT), specifies a minimum of 70 percent VLT for window tinting on the windshield and the windows to the immediate left and right of the driver for commercial vehicles (the DOT does not regulate private vehicles). The DOT does not specify any VLT requirements for rear windows.^[4] State law may regulate laws for private vehicles and may go further than the requirements those set forth by the DOT; private vehicles may have tint on the windows to the immediate left and right of the driver as dark as 20 percent VLT, depending on the state.^[5]
• In Canada, automobile tinting laws are set at the provincial level.^[6]
• In the United Kingdom, regulations set forth by the Vehicle and Operator Services Agency under the Road Vehicles (Construction and Use) Regulations 1986 provide that all front windows in front of the B post can have no less than 70 percent VLT. Windscreens are only allowed tinting outside the sweep of the windscreen wipers to a maximum of six inches from the top of the windscreen.^[7] British police are increasingly cracking down on illegal tinting on vehicles.^[8]

[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 thoroughly 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. Most manufacturers will only warranty their window films when installed by a certified, trained installer.

[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 during tint installation for a perfect finish, making removal of the film very difficult for the novice. As a side note, IGU ( insulated glass units)should not have hair dryers put to them to remove film.

This technique is for the rear window, with the defroster. One way to remove the film is to create humidity inside the vehicle. This is done by using soapy water, a black trash bag, and the sun. 1. Cut open a black leaf trash bag, along the bottom and one side. 2. Lay the bag on the outside of the rear window.3 Trim to the size of the rear window glass.4 Remove to the inside of the car, 5 Spray the inside of the back window with soapy water (water and a few drops of dish soap). 6 Lay the trash bag inside the window, as flat as possible against the glass, also as wet. 7 Shut all doors and make sure the windows are shut. 8 Try to aim the rear window to the sun. 9 Let sit for about 15 minutes, check to see if you can see a difference in the way the adhesive looks. Grab a corner of the film and try to peel it, if this has worked the film will almost fall off. If it is still hard to get off, try again, with the soap. If this doesn't work, take your car to a professional to remove the film.

[edit] References