Common Window Film Technical Terms Explained

Attachment Systems:  Mechanical & Wet Glazed

Attachment systems are used with safety film installations for added fragment retention, anchoring the glazing system to the window frame. Safety film is installed on the interior room surface of glass and then secured to the window frame by either the mechanical or “wet glazed” method. The level of protection desired dictates whether or not an attachment system is required, as well as the type of method used.

Blast Mitigation Film

Another term  for safety & security shatter resistant window film referring to the product’s ability to help hold glass intact during an explosion, minimizing deadly airborne shards.

Dry Adhesive (DA)

A mounting adhesive that uses water to activate and form a chemical bond between the glass and film, adhering the film to the glass during installation. This adhesive offers a strong bond, film clarity and longevity.

Daylight Installation

A common method for installing solar and safety window film. Window film is precut slightly larger than the framed glass pane, then trimmed up to 1/8 inch of the glass edge.

Emissivity (E)

A measurement of a surface’s ability to absorb or reflect radiant energy. The lower the emissivity rating (E), the better the insulation characteristic of the glazing system in regard to heat loss. For windows with film, emissivity refers to the heat reflected back into the room. When using film performance data, lower emissivity ratings are preferred to minimize interior heat loss. 

Fragment Retention Film

A common name for shatter resistant safety & security window film, referring to the primary benefit of safety film: helping to hold glass intact in the event of it being broken.

Glare Reduction (GR)

Glare reduction is the percentage of reduction in visible light transmission through a glazing system without film to that with film.

Infrared (IR) Rejection

Infrared light form the sun is only a portion of the solar spectrum which provides heat through a window. It is important not to confuse IR Rejection with TSER (total solar energy rejection) which is the true indicator of how much energy will be blocked from entering your building.  Many instruments measure IR at 1200

Low-Emissivity

Low-Emissivity, or Low-E, refers to a coating on glass or window film that reduces heat loss through the window film. The lower the emissivity rating, the better the insulation characteristic of the glazing system in regard to heat loss. Emissivity ratings are used mostly in the north where heating days are calculated.  “Low E” for glass windows in southern climates (cooling day climates) are not considered an effective energy conservation product.

Metallized

A process where metals are applied onto a clear, polyester film as an even layer. Different metals produce different hues and performance capabilities to meet the varying consumer needs.

Mechanical Attachment System

This method is used for enhanced glass retention, anchoring 8 Mil or thicker safety film to the window frame with a metal batten system. The safety film is installed to the glass, overlapping the window frame by approximately 1 inch. A metal batten system is placed over the overlapped film and screwed into the existing window frame, securely attaching the window film to the frame. Depending on the type of glass retention needed, the mechanical system can be attached as a one-sided (top / “doggie door type”), two-sided or four-sided installation.

MIL

Unit of length for 1/1000 of an inch (.001”). Used in expressing thickness of films. 1 MIL = 25 microns.

Mylar

A trademark name for polyester film produced by DuPont. Mylar, glass retention, anti-shatter, shatter resistant, fragment retention and blast mitigation are common references to safety and security window film.

P.E.T.

Polyetheylene Terephthalate

Ply

Ply is used to display the number of separate layers of polyester film that are used in the manufacturing process to make a particular window film (tint) product.  Example:  A 1-ply product would consist of one single layer of polyester film where a 3-ply product would be made with three separate layers of various types of polyester film.

Pressure Sensitive Adhesive (PS)

A film mounting adhesive that uses pressure to form a mechanical bond between the film and glass, adhering the film to the glass during installation. Pressure sensitive adhesive is tacky to the touch. All automotive window films and safety window films incorporate PS adhesive.

Safety Film

Safety film is composed of incredibly strong, optical-quality clear or metallized polyester, high-grade ultraviolet inhibitors, special laminating and mounting adhesives, and scratch-resistant coating. The product is retrofit to interior glass surfaces for glass breakage protection. When events such as natural disasters, vandalism or bomb blasts cause glass to break, the film’s flexible construction and pressure-sensitive mounting adhesive help hold the shards on the film. This reduces the potential for personal injury and property damage. Safety film is also referred to as anti-shatter film, glass fragment retention film, blast mitigation film and Mylar.

Shading Coefficient (SC)

Shading Coefficient, SC, is the ratio of solar heat gain passing through a glazing system to the solar heat gain that occurs under the same conditions if the window was made of clear, unshaded double strength glass. The lower the SC number, the better the solar control efficiency of the glazing system.

Solar Absorptance (A)

The amount of solar energy (visible, infrared and ultraviolet,) that is absorbed by the glazing system, expressed as percent.

When sunlight strikes glass, solar energy is either transmitted through the glass, absorbed by the glass or reflected away from the glass. The type of glass and window film applied causes varying absorptance results, expressed as a percent – this is the amount of solar energy that the glass and film retains. Always refer to a manufacturer’s film-to-glass installation recommendation.

Solar Energy

Energy from the sun that is represented by visible light (glare), infrared radiation (heat) and ultraviolet radiation (fading and health hazards). Each form of energy is differentiated by its wavelength.

Solar Heat Gain Coefficient (SHGC)

The percentage of solar energy directly transmitted or absorbed and re-radiated into a building. The lower the SHGC, the better the solar control properties of the film.

Solar Reflectance (R)

The amount of solar energy (visible, infrared and ultraviolet) that is reflected by the glazing system, expressed as a percent.

When sunlight strikes glass solar energy is either transmitted through the pane of glass, absorbed by the glass or reflected away from the glass. The type of glass and window film applied causes varying reflectance results, shown as a percent – this is the amount of solar energy that the glass and film rejects away.

For maximum heat rejection, look for films with a high solar energy reflectance rating. Always refer to a manufacturer’s film-to-glass installation recommendation.

Solar Transmittance (T)

The amount of solar energy (visible, infrared and ultraviolet) that passes through a glazing system, expressed as a percent.

When sunlight strikes glass, solar energy is either transmitted through the pane of glass, absorbed by the glass or reflected away from the glass. The type of glass and window film applied causes varying transmittance results, shown as a percent – this is the amount of solar energy that entered through the glass and film. Always refer to a manufacturer’s film-to-glass installation recommendation.

Sputtering

A process that imbeds metal particles such as silver, stainless steel, copper, gold, titanium and chromium onto polyester film. Rolls of film are unwound and passed over target materials, depositing atoms evenly on the surface of the film through ion bombardment. This ensures long-lasting color and excellent solar performance. Some claim DTI was the first in the industry to sputter-coat window film.

Total Solar Energy Rejected (TSER)

Measures the window film’s ability to reject solar energy in the form of visible light, infrared radiation and ultraviolet light. The higher the TSER number, the more solar energy is rejected way from the window.

U-Value

A measurement of heat transfer through film due to outdoor/indoor temperature differences. The lower the U-value, the less heat transfers. When using performance data, a lower U-value is desirable for heat management.

Ultraviolet Light (UV)

Invisible, powerful wavelengths (shorter than light but longer than X rays) emitted by the sun separated into three types, UV-A, UV-B and UV-C. UV-B causes sunburn, and prolonged exposure can cause skin cancer. Window films block nearly 100% of ultraviolet light from passing through glass. The SCF window films are approved products of the Skin Cancer Foundation.

Visible Light Absorptance (VLA)

The amount of visible light that is absorbed by the glazing system, expressed as a percent.

Visible Light Reflectance (VLR)

The amount of visible light that is reflected by the glazing system, expressed as a percent. A higher VLR rating offers better glare control. Films with higher ratings tend to be more reflective and/or darker.

Visible Light Transmittance (VLT)

The amount of visible light that passes through the glazing system, expressed as a percent. A lower VLT rating tends to be better for glare control, while a higher rating is preferred for maintaining natural light.

Ultraviolet Rejected (UVR)

Ultraviolet rejected is the ratio of ultraviolet (UV) solar energy (wavelength of 300-380nm) that is transmitted by a glazing system to the total solar ultraviolet, uv, energy falling on the glazing system.  Note:  UV energy is not visible to the human eye and is mainly responsible for the degradation and fading of organic matter, upholstery, colors, etc.

Vapor Coating
Vapor coating is another process of applying metal to clear polyester (PET) which uses mainly aluminum.  Speed times for vapor coating is faster than sputter coating.

Wet Glaze Attachment System

This method used for enhanced glass retention secures the safety film to the window frame with a structure sealant, silicone adhesive (similar to caulking). Dow Corning 995 is commonly used silicone adhesive in the industry.  The safety film is first installed to the glass as a daylight installation and then secured to the frame with a structural sealant - Dow 995 is one of the products commonly used. Sealant is applied around all four edges of the film, overlapping the film and touching the frame to create a bond between the film and frame. This method is sometimes referred to as a chemical attachment system.