Window Film Glossary
Absorptance: The amount that is taken into a medium.

Deposition Process:
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.