Window Film Technical Terms Explained
Attachment Systems: Mechanical & Wet
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.
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
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, 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
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
Unit of length for 1/1000 of an inch (.001”). Used in expressing thickness
of films. 1 MIL = 25 microns.
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
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.
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 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
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.
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.
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.
The amount of solar energy (visible, infrared and ultraviolet) that passes through a glazing system, expressed
as a percent.
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
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.
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)
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 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
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