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Glossary: Industry Terms and Definitions

The easiest way to learn about window film terminology

Window Film Glossary & Terms

This glossary defines common terms that you might see in the window film industry, or throughout our Help Center. 🔍

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According to Google, the definition of ambient means the immediate surroundings or encompassing atmosphere. In terms of window film, ambient can be used to describe the temperature of a room when window film is installed. For example, installing solar film to your home windows can help reduce the ambient temperature making you feel more comfortable.

Annealed Glass

Annealed glass is what most typical windows are made of. Annealed glass is typically softer than other types of glass and has been thermally treated and then slowly cooled to relieve internal stress. It is important to note that if broken, annealed glass typically breaks in longer pieces which could be a safety hazard.

Art/Opalescent/Cathedral Glass

Art glass typically includes cathedral glass, stained glass, opalescent glass and colored translucent glass. It is created by the rolling process and is usually 1/8-inch thick. It is important to note that art glass cannot be tempered.

Attachment Systems

When it comes to window film, attachment systems are used mainly with security window film. The purpose of attachment systems is to hold the window film and the window frame together to create the maximum amount of strength. When installed with security window film, attachment systems will make the window even stronger and help prolong forced entry time even more than security window film alone.



In terms of window film, the term "blast" typically refers to the energy of an explosion point by which glass is shattered into a million pieces. Installing blast mitigation window film or security window film helps hold glass together in case of a blast, significantly increasing safety.

Blast Overpressure

Blast overpressure is the rise of negative air pressure after a blast. Blast mitigation window film and security window film have specific performance requirements to mediate this overpressure.

BTU (British Thermal Unit)

A unit of measure which is one way to compare the performance of different window films.



Ceramic is color stable, non-conductive, non-corroding metal component that gets deposited onto polyester window film to increase the performance and heat rejection for the film.

Clear Glass

Clear glass is a type of glass that has no metals or dyes added to it. It is colorless and is the majority of flat glass that is used is clear glass.

Clear Dry Adhesive (CDA)

Clear dry adhesive is a water activated adhesive used to form the chemical bond between window film and glass. When bound to the pane, clear dry adhesive will dry clear and not be noticeably apparent. 


Daylight Installation

Daylight installation means you installed window film from edge-to-edge of a piece of glass with a small daylight gap between the film and frame.

Dual Reflective

Dual reflective window film means the outside surface is more reflective than the inside surface. If you are outside looking in, it will look similar to a mirror. If you are inside looking out, your view isn't hindered.

Dyed Film

Dyed film is exactly what it sounds like, a dye based product. The dye absorbs the sun's heat and come in various shades. The darker the film, the more heat is absorbed and reduced.


Emissivity (E)

Emissivity is the measure of the thermal energy a surface is emitting. The lower the emissivity number the more energy that gets radiated back into the room.


Figured/Patterned Glass

Figured or patterned glass is created by a pattern that is etched on one or both rollers and have limited color options. Typically, figured or patterned glass is called decorative glass and is not transparent.


Glare Reduction

Glare reduction refers to the amount of glare or visible light that is reduced when window film is installed.

Glass Edge Strength

Glass edge strength is essentially how strong the glass is. Glass edge strength depends on a variety of different factors including the size, thickness, how the glass is cut and the glazier's treatment. If edge stress is greater than edge strength, glass breakage occurs.


Heat Strengthened Glass

Heat strengthened glass is made similar to tempered glass in the sense that the glass is heated and then cooled. Heat strengthened glass is about twice that of annealed glass.

Hot Spots

Hot spots are areas of a space that get really hot because of solar radiation and solar energy. We often will install window film to the hot spots in houses to regulate the temperature and make it comfortable and balanced.

Hybrid Film

Hybrid window film is a combination of dyed film and metalized film. Hybrid film blocks light and has a darker appearance. Hybrid film does not have a reflective appearance and is very affordable.


Infrared Light

Infrared light is a form of light that is invisible to the human eye. When you think of infrared light, you can think of it as heat.

Infrared Rejection

Infrared rejection is the amount of infrared light that is blocked by window film, either by reflecting or absorbing it. When we are talking about infrared rejection, we are generally talking about the amount of infrared energy that is being blocked from a space.

Insulated Glass

Insulated glass is another term for double pane glass. It essentially is two panes of glass that are sealed together by vacuum glass to reduce heat in a space. In terms of window film, double pane or insulated glass is generally brought up when discussing what type of film is appropriate for your glass. There is some window film that is not appropriate for double pane glass because the high heat absorption will actually crack the glass.


Laminated Glass

Laminated glass is similar to insulated glass in the sense that is it comprised of two layers of glass, but is held together by a layer of plastic. Laminated glass is also a safety glass so in the event of breaking, the glass is held together by the layer of plastic that holds the two pieces of glass together.

Light to Solar Heat Gain Ratio (LSG)

Light to solar heat gain ration is the ratio of visible light transmittance of the energy radiated back into the space.


Lite is a single pane of glass.

Low-Emissivity (Low-E)

Low-Emissivity or Low-E is a coating on glass or even window film that will reduce even more heat loss and will have better insulation than standard glass and window film alone.

Luminous Efficacy

Luminous efficacy is the amount of light you are able to see for a given amount of power used.


Mechanical Attachment System

Mechanical attachment system is another type of attachment system that is used primarily for 8Mil thickness and higher. It is a metal system that is installed over the film and screwed directly into the window frame, securing the window film to the frame.

Metallic Film

Metallic window film is made with the use of sputtering or deposition processes to deposit metal onto the surface. Metallic window films look highly reflective and will reduce a large amount of heat and glare.


We just talked about how metallic film is comprised of metal. Metalized is the process where metal is applied in an even layer onto the film, actually creating the metallic film. Different metals will produce different colors and will block different amounts of heat and glare.


MIL is the unit of length used to describe the thickness of window film. A MIL is .001 of one inch. In terms of window film, security window film and anti graffiti film come in different thicknesses like 4mil, 6mil, 8mil, 14mil and more. The higher the number, the thicker the window film is and more difficult to get through.



Similar to ceramics, Nano-Ceramics are smaller particles allowing you to have better visibility through the film. Nano ceramics make the window film less reflective and gives the film better IR rejection.

Negative Phase

Negative phase is commonly referred to as the "suction wave", and is the part of a blast wave where pressure is lower than the surrounding pressure.


Positive Phase

As you can imagine, positive phase is the opposite of negative phase. It refers to the part of the blast wave where pressure is above the surrounding pressure.

Pressure Sensitive Adhesive (PSA)

Pressure sensitive adhesive uses pressure to bond to the glass and becomes increasingly stronger during the drying process and has immediate adhesion.


Reflected Pressure

Reflected pressure is the pressure felt by something standing in the path of a blast wave. In terms of window film, this could be any object in an office space or home that would be impacted by a bomb blast.

Reflective Glass

Reflective glass is coated with a layer of metal or metallic oxide that will make the glass look like a mirror and make it difficult for anyone to see inside.

Rolled Glass

Rolled glass is the process of producing a desired glass thickness by passing a roller over molten glass between thickness strips.


Safety Film

Safety film is a layer of window film that is applied directly to glass surfaces for glass breakage protection. Safety and security window film strengthens glass by 2-3 times and helps prolong forced entry time. Safety window film helps protect in the event of a natural disaster, intruder or bomb blast.

Shading Coefficient (SC)

Shading coefficient is the ratio of the amount of heat that is passed through a window with window film to a window with no window film. The lower the shading coefficient number, the better the shading quality of the window film.

Sheet Glass

Sheet glass is a type of glass commonly used to make windows and glass doors. Sheet glass typically has a thickness of 1/8-inch or less.


Side-on-pressure is the pressure felt to the top and sides of an object when a blast surrounds it or passes over it.


Roll slitting refers to cutting a large roll of film into narrower rolls. We see this a lot when we are ordering the film. If we don't need a full roll of film, the manufacturer can cut the roll down as to not have a lot of waste.

Spandrel Glass

Spandrel glass is opaque glass that will hide features between floors or prevent people from seeing things like vents and wires. You can think of it like a frosted window film or blackout window film that will prevent people from seeing whats on the other side.

Solar Energy

Solar energy is visible light, heat, and ultraviolet radiation that is produced by the sun.

Solar Heat Gain Coefficient (SHGC)

This value is similar to the shading coefficient but it also takes into account the energy that is radiated back into the room from the window's increased heat absorption. Solar heat gain coefficient is represented by a number from 0 to 1. The lower the number means a low coefficient, which means low heat gain. The higher the number means a high coefficient, which means high heat gain. The lower the solar heat gain coefficient, the better performing the window film is.

Spectrally Selective

Spectrally selective window film blocks certain wavelengths of radiation while still allowing a lot of visible light transmittance. In layman's terms, spectrally selective window film will reject the heat, while still allowing in natural light leaving your view unaffected.


There are different way to manufacture and create window film. Sputtering is one of those ways and is a process that takes metal alloys and combines them in a vacuum chamber with different gasses and then applied to the window. Like we have said before, some metals are heavier and some are lighter so they will have different hues of color.


Tempered Glass

Tempered glass is about four times stronger than annealed glass. When broken, tempered glass stays in small pieces, which is much safer than long, jagged pieces, like some other types of glass.

Thermal Stress

Thermal stress refers to the stress caused by different temperatures. If too much heat is absorbed or if there is rapid cooling from a high temperature, this causes thermal stress and could result in your glass cracking. Earlier, when we were talking about double pane glass, we had said that only certain films can be applied or too much heat is absorbed and the glass can crack. This is because of thermal stress and is exactly what we are talking about.

Tinted/Heat Absorbing Glass

Tinting and heat absorbing glass is made by adding different colors to the clear glass. These different colors will all block different amounts of heat and glare based off their color and thickness.

Total Solar Energy Absorptance

Total solar energy absorptance is the amount of solar energy that is absorbed into the glass.

Total Solar Energy

Total solar energy includes all of the energy in the solar spectrum including UVA and UVB rays, infrared energy and even heat.

Total Solar Energy Rejected (TSER)

Total solar energy rejected, or heat rejection, is the amount of heat that is blocked from a space. If you read our case studies or blogs, you will see us commonly say things like, "solar film can block up to 75% of heat." That 75% of heat is the total solar energy rejected.

Total Solar Reflectance

Total solar reflectance is the total solar energy that is reflected off of the glass. This energy stays outside and does not come back inside the home or building.

Total Solar Transmittance

Total solar transmittance is the amount of solar energy that makes its way through the glass and into the home or office space. The lower the solar transmittance number, the less amount of solar radiation is transmitted.


Transmissivity is the amount of radiant energy that passes through glass.



The U-Value is the capability of heat to get through one square foot of window film for each degree difference in temperature.

Ultraviolet Light (UV)

Ultraviolet light is the harmful part of the solar energy spectrum. Ultraviolet light is responsible for the sun fading furniture, artwork and floors. Again, if you have read our case studies or blogs or have read through our website, you will know that all window film blocks 99% of UVA and UVB rays. While window film won't prevent your belongings from fading, it will help prolong it.

Ultraviolet (UV) Inhibitors

Ultraviolet inhibitors are the chemical and material elements in window film that will block those harmful UVA and UVB rays.

Ultraviolet (UV) Transmittance

The ultraviolet transmittance is the amount of ultraviolet light that is still still transmitted. In this case of window film, the ultraviolet transmittance is 1% since all window film blocks 99% of UVA and UVB rays.

Ultraviolet (UV) Rejection

The ultraviolet rejection is the amount of UV energy that is blocked by window film. When it comes to window film, the ultraviolet rejection is 99%.


Visible Light

Where infrared light is invisible to the human eye, visible light are wavelengths the human eye can see. We perceive visible light as colors ranging from red, which are longer wavelengths, to violet, which are shorter wavelengths.

Visible Light Absorptance (VLA)

Visible light absorptance is the amount of visible light that is absorbed by the window film. The lower the number, the less light is absorbed and the lighter the window film will be. The darker the window film, the more amount of heat is absorbed.

Visible Light Reflectance (VLR)

Visible light reflectance is the amount of visible light that is reflected from the window film. The lower the number, the less visible light is reflected.

Visible Light – Reflected Interior

Visible light-reflected interior refers to the amount of visible light that is reflected off the interior of the window, or when you are inside looking outside. The more reflective the glass is, the more the window will look like a mirror from the inside looking out.

Visible Light – Reflected Exterior

Visible light-reflected exterior is the opposite of visible light-reflected interior. This is refers to the amount of visible light that is reflected off the exterior of the window, or when you are outside looking inside. The more reflective the glass is, the more the window will look like a mirror from the outside looking in.

Visible Light Transmittance (VLT)

Visible light transmittance refers to the amount of visible light that goes through the window film and is let into a home or business. This essentially is how light or dark the window film is. For example, if you are installing Ceramic 30 (C30), the VLT is 30%, meaning 30% of the light is passing through the film and being let into the space. If you install Ceramic 40 (C40), the VLT is 40%, meaning 40% of the light passing through the film is let into the space. What this is saying is C30 is slightly darker than C40 and will let a little less light pass through into the space.


Wet Glaze

Wet glaze refers to the silicone or sealant that is used for the attachment systems to secure the window film to the window frame.

Wired Glass

Wired glass is made by welding a wire into the molten glass just before entering the rolls. Wired glass has a pattern on one or both sides. Wired glass is used predominantly in institutional buildings and fire rated windows and doors.