Everything to know about Window Film

Window Film Glossary

Window Film Glossary


The immediate surroundings or encompassing atmosphere.


Annealed Glass

Annealed glass, manufactured by pouring molten glass onto a bed of molten tin which is then cooled, is the product most people think of as “plate” glass. This flat glass product has little residual surface compression and must be handled carefully to minimize thermal stress. When shattered, annealed glass breaks into sharp shards.


Art/Opalescent/Cathedral Glass

Often called art glass, opalescent glass, cathedral glass, or stained glass, colored translucent glass is also produced by the rolling process, but generally in small batches. Usually, there are variegated colors within each sheet produced and no two sheets will match for hue. Thickness will vary within a sheet, as well as from sheet to sheet. The maximum thickness produced is usually 1/8-inch. When used as a glazing material, art glass should be glazed in the same manner as tinted/heat absorbing glass. Art glass cannot be tempered.


Attachment Systems

Chemical or mechanical restraint systems that improve the performance of safety & security window film during powerful winds, blasts, and smash-and-grab break-ins.



A temporary change in the gas density, pressure, and velocity of the air surrounding an explosion point. If the initial change is in intervals, it is known as a shock wave. If the initial change is gradual, it is referred to as a pressure wave.


Blast Overpressure

The violent rise in air pressure, also known as a shock wave, over and above normal atmospheric pressure (14.786 pounds per square inch).


BTU (British Thermal Unit)

A traditional unit of heat, the British Thermal Unit (BTU) is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit (1 BTU = 252 Calories).


Clear Glass

Clear glass is made of silica sand with added alkaline salts such as lime potash and soda. It is colorless, has a visible light transmittance ranging from 75% to 92%, depending upon thickness, and constitutes the bulk of the flat glass that is used.


Clear Dry Adhesive (CDA)

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


Daylight Installation

The process of applying window film to a piece of glass from edge-to-edge. The small untreated area of glass that remains is referred to as a “daylight gap”.


Dual Reflective

Dual reflective window films offer reduced interior reflectance, allowing you to maintain your view though the glazing system.


Dyed Film

Window film that uses either a submersion process or a dyed adhesive process to deposit dye onto its surface in order to achieve the qualities and look of tinted film.


Emissivity (E)

The ability of the surface to reflect infrared energy. For window film, this means how much heat it will re-radiate back into a room. Low E glass and films have low emissivity, which means they reflect a lot of heat back into the room and is the desired effect in cold climates.


Figured/Patterned Glass

Figured or patterned glass is produced domestically by the continuous pour process in thicknesses of 1/8-inch to 7/32-inch. A pattern etched on one or both of the rollers is reproduced on the glass. Colors, while available, are extremely limited. Figured glass is often called “obscure” or “decorative” glass. It has powerful light-diffusing properties, but it is not transparent. The degree of diffusion achieved depends on the pattern and whether the pattern is on one or both sides. Some patterns cannot be tempered for safety glazing use because of their depth.


Float Glass

The float glass process accounts for more than 90% of the flat glass currently produced in the United States. Molten glass is poured continuously from a furnace onto a large bed of molten tin. The molten glass literally floats on the tin, spreading and seeking a controlled level in the same manner as water poured onto a smooth, flat surface. In the controlled level-seeking process, the molten glass is allowed to spread to a width of 90-inches to 140-inches, depending on the furnace size and glass thickness being produced. The glass slowly solidifies as it travels over the molten tin. Then, it is cooled under controlled conditions and afterwards, emerges as a continuous ribbon of glass at essentially room temperature. The product is now flat, fire-finished, and with virtually parallel surfaces.


Glare Reduction

The percentage by which visible light is reduced by the addition of window film.


Glass Edge Strength

Glass is made to withstand from between 3000 to 5000 psi (210 to 350 kg/cm) of edge stress. When edge stress exceeds edge strength, breakage occurs. Edge strength is dependent on glass size, thickness, how it is cut, and a glazier’s treatment of the edge. A straight clean edge is the strongest. If edges are damaged, they can reduce edge strength by up to 50%.


Heat Strengthened Glass

Heat strengthened glass is produced by a process similar to that of tempered glass. Some equipment can fabricate both. The glass is heated to approximately 1100 degrees Fahrenheit and the cooling process is slower than for tempered glass. The strength developed for this type of glass is about twice that of annealed glass.


Hot Spots

These are areas particularly affected by solar radiation and the imbalance of solar energy.


Hybrid Film

Window film that is comprised of a combination of metallic film and dyed film to achieve the qualities and look of tinted film.


Infrared Light

A form of electromagnetic radiation with wavelengths between 0.7 micrometers (0.0007 millimeters) and 1 millimeter. These wavelengths are longer than those of visible light, but shorter than those of microwaves. (The prefix “infra” means “below”; infrared refers to radiation below the frequency of red light). Infrared light is primarily thermal radiation, and we can think of this as being heat.


Infrared Rejection

The amount of infrared (IR) energy that is blocked by the film, either by reflecting or absorbing. This value is for the whole IR region of the solar spectrum, roughly 780nm up to 2500nm.


Insulated Glass

Double insulated glass consists of two panes of glass that enclose a hermetically sealed air space. The panes are held apart by a spacer around the entire perimeter. The spacer contains a desiccant, which is a moisture absorbent material that serves to keep the enclosed air free of visible moisture.


Laminated Glass

Laminated glass is a type of safety glass consisting of two or more layers of glass held in place by an interlayer of clear or tinted polyvinyl butyl (PVB). The application of heat and pressure bonds the glass and plastic interlayer into one unit. When laminated glass is fractured, the particles of glass tend to adhere to the plastic, offering protection against flying or falling particles. Some combinations of glass and plastic thicknesses do qualify as safety glazing materials under the criteria of the American National Standards Institute (ANSI) Z97.1-1984 and Federal Standard 16 CFR 1201.



A sheet or pane of glass.


Low-Emissivity (Low-E)

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.


Luminous Efficacy

The ratio of visible light transmission (VLT) to solar heat transmission for a window. A higher luminous efficacy means the film has high heat rejection given its VLT.


Mechanical Attachment System

This method is used for enhanced glass retention, anchoring 8 Mil or thicker safety & security film to the window frame with a metal batten system. The safety & security 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), two-sided, or four-sided installation.


Metallic Film

Window film that uses either a sputtering or deposition process to deposit metals onto its surface to achieve the qualities and look of tinted film.



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



The Unit of length for 1/1000 of an inch (.001-inch). It is used in expressing thickness of films, i.e., 1 MIL = 25 microns.



Ceramics are tough, stable materials used in space shuttles, integrated circuit components, and industrial cutting tools. Nano-Ceramics are atomic-fine, equivalent to 0.000000001m discrete optical coatings, which are deposited through reactive plasma processes.


Negative Phase

Also referred to as “the suction wave”, negative phase is the portion of a blast wave in which pressure is below ambient.


Positive Phase

The portion of a blast wave during which pressure rises sharply and is above ambient.


Pressure Sensitive Adhesive (PSA)

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 & security window films incorporate PSA.


Reflected Pressure

Amount of pressure felt by an object that is standing directly in the path of an expanding blast wave.


Reflective Glass

Reflective glass is clear or tinted glass coated with a very thin layer of metal or metallic oxide.


Rolled Glass

The rolled glass process started with the pouring of molten glass from a furnace, then feeding it through rollers to produce the desired thickness. The glass ribbon is then cooled under controlled conditions. There are three general types of rolled glass: figured/patterned, wired, and art/opalescent/cathedral glass.


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 together, keeping them from shattering. 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)

The ratio of heat passing through a filmed window to heat passing through clear unfilmed glass. The lower the shading coefficient number, the better the shading qualities of the installed window film.


Sheet Glass

The sheet glass process accounts for a very small portion of U.S. glass production. Some imported sheet glass will continue to be used, mainly in thickness of 1/8-inch and less.



The pressure felt on the top and sides of an object as a blast pressure wave surrounds and passes over and around it.



Roll slitting, also known as log slitting or rewind slitting, is a shearing operation that cuts a large roll of material into narrower rolls. The log slitting terminology refers back to the olden days of saw mills when they would cut logs into smaller sections. They would also use these saw mills to cut iron rods into smaller sections.


The multiple narrower strips of material are known as mults (short for multiple). By today’s definition, slitting is a process in which a coil of material is cut down into a number of smaller coils of narrower measure.


Slitting is considered a practical alternative to other methods due to its high productivity and the versatility of materials it can manage. Rewind slitting involves rewinding the material through a number of knives to form narrower rolls of materials. The machine used is called a slitter rewinder, a slitter or a slitting machine – these names are used interchangeably for the same machines.


Spandrel Glass

Spandrel glass panels are heat strengthened or tempered glasses with a ceramic frit color permanently fused to one of the surfaces. Glass in spandrel areas is not subject to corrosion as are some other spandrel materials. Decorative aesthetics and economies can be obtained using a single framing system for an entire wall. Glass spandrel panels can also save energy when insulation is placed behind them.


Solar Energy

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


Solar Heat Gain Coefficient (SHGC)

Similar to the shading coefficient, except this value also takes into account energy that is re-radiated back into the room from the glass heating up due to increased absorption. The lower the SHGC, the better the solar control properties of the film.


Spectrally Selective

Spectrally selective window films block only select wavelengths of radiation while maintaining a high amount of visible light transmittance. These premium films reject the heat you don’t while letting in the natural light you love.


Sputter (Deposition)

Sputter deposition is a physical vapor deposition (PVD) method of depositing thin films by sputtering. This involves ejecting material from a “target” that is a source onto a “substrate” such as a silicon wafer.


Resputtering is re-emission of the deposited material during the deposition process by ion or atom bombardment. Sputtered atoms ejected from the target have a wide energy distribution, typically up to tens of eV (100,000 K). The sputtered ions (typically only a small fraction — order 1% — of the ejected particles are ionized) can ballistically fly from the target in straight lines and impact energetically on the substrates or vacuum chamber (causing resputtering).


Alternatively, at higher gas pressures, the ions collide with the gas atoms that act as a moderator and move diffusively, reaching the substrates or vacuum chamber wall and condensing after undergoing a random walk. The entire range from high-energy ballistic impact to low-energy thermalized motion is accessible by changing the background gas pressure. The sputtering gas is often an inert gas such as argon. For efficient momentum transfer, the atomic weight of the sputtering gas should be close to the atomic weight of the target, so for sputtering light elements neon is preferable, while for heavy elements krypton or xenon are used. Reactive gases can also be used to sputter compounds. The compound can be formed on the target surface, in-flight or on the substrate depending on the process parameters.

The availability of many parameters that control sputter deposition make it a complex process, but also allow experts a large degree of control over the growth and microstructure of the film.



Sputtering is 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 enduring color and excellent solar performance.


Tempered Glass

Tempered glass is produced by subjecting annealed glass to a special heat-treating process. The most commonly used process is to heat the glass uniformly to approximately 1150 degrees Fahrenheit and then cool it swiftly by blowing air uniformly onto both surfaces at the same time. The cooling process locks the outer surfaces of the glass in a state of high compression and the central portion, or core, in compensating tension.


The color, clarity, chemical composition, and light transmission characteristics remain unchanged. Likewise, compression strength, hardness, specific gravity, expansion coefficient, softening point, thermal conductivity, thermal transmittance, and stiffness are the same. The only physical property that changes is tensile or bending strength.


Under uniform loading, tempered glass is about four times stronger than annealed glass of the same size and thickness, and is therefore more resistant to thermally induced stresses, cyclic wind loading, and hail stone impacts. When broken, tempered glass splits into a multitude of small fragments of more-or-less cubical shape. Therefore, it qualifies as a safety glazing material under the criteria of Federal Standard 16 CFR 1201 and the American National Standards Institute (ANSI) Z97.1-1984 when so labeled and certified.


At times, spots or blotches may be visible on tempered glass, especially when viewed through polarizing lenses or in certain types of reflected light. The intensity will vary with lighting conditions and viewing angles. This is caused by the strain pattern induced during the cooling stage and is not intrinsically a cause for rejection.


Thermal Stress

When exposed to solar radiation all glass absorbs energy. Tinted glass absorbs more energy than clear glass. This occurs when there is a temperature differential between the center of the glass and its shaded edges. The ability of the glass to not break is determined by its edge strength.


Tinted/Heat Absorbing Glass

Tinted or heat absorbing glass is produced by adding various colorants to the normal, clear glass batch to create a desired color. The four colors available by the float process are bronze, gray, green, and blue. Visible light transmittance will vary from 14% to 83%, depending upon color and thickness. The color density is a function of thickness and increases as the thickness increases. Visible light transmittance will also decrease as thickness increases.


Tinting reduces the solar transmittance of glass, has little effect upon solar reflectance, and thus increases solar absorption (heat). This explains why heat strengthening or tempering is sometimes required for the thicker tinted glasses. Adding a metallic coating also has the same effect on thinner glasses.


Total Solar Energy Absorptance

The amount of total solar energy that is absorbed into the glass. This heats up the glass, making it hotter to the touch, and re-radiates a small amount of heat back into the building or automobile. The majority of absorbed energy is kept out of the car though.


Total Solar Energy

All the energy in the solar spectrum that reaches us on the earth’s surface. This includes UVA and B, visible light, and infrared energy up to roughly 2500nm. Heat often refers to the total solar energy.


Total Solar Energy Rejected (TSER)

The total amount of solar energy that is kept out of the building or automobile. Commonly referred to as heat rejection.


Total Solar Reflectance

The amount of total solar energy that is reflected off of the glass and directed back outside. This energy does not come into the building or automobile.


Total Solar Transmittance

The amount of total solar energy that passes through the glass into the building or automobile. The lower the number, the less solar radiation transmitted.



The amount of radiant energy (energy of electromagnetic waves) transmitted from a radiating object through the atmosphere to a target after reduction by atmospheric absorption and scattering.



The ability of heat to transfer through one square foot of window film for each degree Fahrenheit difference in temperature. The local climate or environment in which the window is located affects the level of heat transfer and the rate. In summer, heat transfers from the outdoor air to indoor air.


In winter, heat transfers from indoor air to outdoor air. The lower the U-value, the better insulating qualities of the installed window film so heat is kept inside in cold climates.


  • Median: refers to the part of the U-factor/U-value chart that applies to “mild winter” conditions.

  • Design: refers to the part of the U-factor/U-value chart that applies to “severe winter” conditions.

Ultraviolet Light (UV)

The damaging portion of the solar energy spectrum that causes fading and deterioration to fabrics, furniture, and furnishings. 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 age skin and cause skin cancer. Window films block nearly 100% of ultraviolet light from passing through glass.


Ultraviolet (UV) Inhibitors

Chemical and material elements added to products such as window film and lotions to block and/or filter out varying amounts of damaging UV rays.


Ultraviolet (UV) Transmittance

The percent of ultraviolet light (UV) that is transmitted by the installed window film. The lower the number, the less UV light is transmitted.


Ultraviolet (UV) Rejection

The amount of UV energy blocked by the film, either by reflecting or absorbing it. This energy does not enter the building or automobile. The higher the number, the more UV rays are blocked.


Vapor / Evaporation (Deposition)

Evaporation is a common method of thin film deposition. The source material is evaporated in a vacuum. The vacuum allows vapor particles to travel directly to the target object (substrate), where they condense back to a solid state. Evaporation is used in microfabrication, and to make macro-scale products such as metallized plastic film.

Evaporation involves two basic processes: a hot source material evaporates and condenses on the substrate. It resembles the familiar process by which liquid water appears on the lid of a boiling pot. However, the gaseous environment and heat source are different.

Evaporation takes place in a vacuum, i.e. vapors other than the source material are almost entirely removed before the process begins. In high vacuum (with a long mean free path), evaporated particles can travel directly to the deposition target without colliding with the background gas. (By contrast, in the boiling pot example, the water vapor pushes the air out of the pot before it can reach the lid.) At a typical pressure of 10-4 Pa, an 0.4-nm particle has a mean free path of 60 m. Hot objects in the evaporation chamber, such as heating filaments, produce unwanted vapors that limit the quality of the vacuum.


Evaporated atoms that collide with foreign particles may react with them; for instance, if aluminium is deposited in the presence of oxygen, it will form aluminium oxide.


Visible Light

Electromagnetic radiation at wavelengths that we can see. We perceive this visible light as colors ranging from red (longer wavelengths; ~700 nanometers) to violet (shorter wavelengths; ~400 nanometers).


Visible Light Absorptance (VLA)

The percent of total visible light absorbed by the installed window film. The lower the number, the less visible light is absorbed.


Visible Light Reflectance (VLR)

The percent of total visible light reflected by the installed window film. The lower the number, the less visible light is reflected. A higher VLR rating offers better glare control and films with higher ratings tend to be more reflective and/or darker.


Visible Light – Reflected Interior

The amount of visible light that is reflected off the interior surface of the window. This is seen when standing inside the building looking out. A higher reflectance value means the window looks more like a mirror from the inside.


Visible Light – Reflected Exterior

The amount of visible light that is reflected off the exterior surface of the window. This is seen when standing outside the building or automobile. A higher reflectance value means the window looks more like a mirror from the outside.


Visible Light Transmittance (VLT)

The amount of visible light that passes through the installed window film into a building or automobile. This is how light or dark the film is. As an example, limousines usually tint their windows with films that have a VLT of 5%.


Visual Acuity

Visual acuity refers to the clarity of your vision. Some people believe that the application of window film distorts their outdoor view when they are indoors. But due to visual acuity, eyes adjust to the amount of light they are receiving, so even when film reduces views from the outside looking in, the same is not true for the reverse.


Wet Glaze

The application of a silicone sealant or similar liquid-state material around the perimeter of the glass to secure the glass to a frame (e.g., a bead of silicone mastic used to bond the film to the glass to the window frame).


Wired Glass

Wired glass is fabricated on the same equipment as figured/pattered glass. A welded wire netting or parallel wires are introduced into the molten glass just before entering the rolls to embed the wire into the glass. Patterned wired glass has a pattern on one or both sides and is sometimes called “rough” wired glass. Polished wire glass is made by grinding and polishing rolled wired glass blanks.


Tinted/heat absorbing wired glass is only available as an import.


The heat absorbing characteristic combined with the typically poor cut edges and the wire netting can cause a high rate of breakage from thermal stress, especially in non-vertical applications. The major uses of wired glass are in institutional buildings and fire rated windows and doors. All wires must be completely embedded in the glass. Some misalignment of the wires may be noticeable, but this is not considered cause for rejection.


Wired glass cannot be tempered.