Window Film Glossary

The amount that is taken into a medium.

A form of physical vapor deposition (PVD) often used for deposition of metal films. Film is drawn through a tank containing metal ingots where a vacuum is created by reducing the pressure in the tank, which is then flooded with argon gas and the ingots are heated. The heat causes the metal to give up particles that migrate to the film's surface.

Dyed Film

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

Emissivity

The measure of surface's ability to absorb or reflect far-infrared radiation. The lower the emissivity rating, the better the insulating qualities of the window film/glass system.

Hybrid Film

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

Infrared Light

A form of electromagnetic radiation with wavelengths between 0. 7 micrometres (0.0007 millimetres) and 1 millimetre. 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.

Metallic Film

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

Polyester Film

Polyesters are made from chemical substances found mainly in petroluem and are manufactured in fibers, films, and plastics. Polyester film (PETF) is a semi-crystalline film used in many applications such as videotape, high quality packaging, professional photographic printing, X-ray film, floppy disks, etc.

Reflectance

The amount that is bent or sent back by a medium.

Shading Coefficient

The ratio of solar heat gain passing through window film to the solar heat gain that occurs under the same conditions if the window were made of clear, unshaded double strength window glass. The lower the number, the better solar shading qualities of the window film/glass system.

Solar Absorptance

The percent of incident solar radiation that is absorbed by the window film/glass system. The lower the number, the less solar radiation absorbed.

Solar Heat Gain Coefficient

The ratio of total solar heat passing through a given window product relative to the solar heat incident on the projected window surface at normal solar incidence (I.E. perpendicular to the glazing surface). The lower the coefficient number for a particular window film/glass system, the better it is able to reduce heat.

Solar Reflectance

The percent of incident solar radiation that is reflected by the window film/glass system. The lower the number, the less solar radiation reflected.

Solar Transmittance

The percent of incident solar radiation that is transmitted through the window film/glass system. The lower the number, the less the solar radiation transmitted.

Sputtering Process

A form of physical vapor deposition (PVD) often used for deposition of metal films.Sputtering involves knocking metal atoms off a disc of pure metal with charged, energetic, chemically inactive atoms called ions (from a plasma). The metal atoms will re-deposit and build on top of polyester film .

Total Solar Energy Rejected

The percent of total solar energy (heat) rejected by the window film/glass system. The higher the number, the more total solar energy (heat) rejected.

Transmittance

The amount that is allowed to pass through a medium.

U-Value

The ability for heat to transfer through 1 square foot of window film for each 1° fahrenheit difference in temperature. It is dependent upon the local climate or environment that the window is located in effects 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 window film/glass system.

Ultraviolet Light

Light having a shorter wavelength and higher energy than visible light. Ultraviolet light is potentially damaging to library, archive and museum objects. Removing UV light can reduce the rate of deterioration. Certain acrylic sheets have UV filtering chemicals built into them.

Ultraviolet Transmittance

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

Visible Light

electromagnetic radiation at wavelengths which the human eye can see. We perceive this radiation as colors ranging from red (longer wavelengths; ~ 700 nanometers) to violet (shorter wavelengths; ~400 nanometers).

Visible Light Absorptance

The percent of total visible light that is absorbed by the window film/glass system. The lower the number the less visible light absorbed.

Visible Light Reflectance

The percent of total visible light that is reflected by the window film/glass system. The lower the number the less visible light reflected.

Visible Light Transmittance

The percent of total visible light that is transmitted through the window film/glass system. The lower the number the less visible light transmitted.