Industry Terms & Definitions

Annealed Glass:
The typical type of a sheet of plate glass; the most common window glass, also known as Annealed Float Glass, produced with relatively low heat levels.

Alarm Glass:
Is a special laminated glass designed and manufactured for security purposes. The interlayer is embedded with a very thin wire and then "sandwiched" between two or more sheets of glass.

Acid Polishing:
This process is used to remove obscurities from etched surfaces.

Anti-Reflective Glass:
Anti-reflective glass is float glass with a specially designed coating that reflects a very low percentage of light. It offers maximum transparency and optical clarity, allowing optimum viewing through the glass at all times.

Bent Glass:
Bent glass is normal glass, which is curved with a special process.

Bending:
A process used to produce bent glass in which a plate of glass is placed in a horizontal mold and then slowly heated at approximately 600°C, at which the glass softens sufficiently and takes the shape of the mold. The glass is then slowly cooled to avoid any internal stress.

Bulletproof Glass:
Designed and produced to resist penetration by bullets.

Blast-Resistant Glass:
The ability of glass to stand blast pressure from an explosion.

Double Glazing:
Two panes of glass enclosing a hermetically sealed air space.

Distortion:
An optical effect obtained on the glazing surface.

Double Glazed Units:
Two panes of glass enclosing a hermetically sealed air space.

Enameled Glass:
Enameled glass is tempered or heat-strengthened glass, one face of which is covered, either partially or totally, with mineral pigments. Beside its decorative function, enameled glass is also a solar ray controller.

Fenestration:
The placement of window openings in a building.

Fire Resistant Glass:
Special type of glass designed to contains flames and inflammable gas for a longer period.

Fire Resistant Glass - Heat Transmission:
Contain flames and inflammable gas for a short period of time, but does not prevent the transmission of heat to the other side of the glazing (example: wired glass, reinforced laminated glass).

Fire Resistant Glass - Fire-Insulating:
Contains flames and inflammable gas for a longer period of time and prevents not only the transmission of flames and smoke but also of heat to the other side of glazing.

Frame:
The fixed frame of a window that holds the sash or casement as well as the hardware.

Gas Fill:
A process in which argon or krypton is filled into the cavity of insulating glass to improve thermal performance.

Gaskets:
Pre-formed glazing materials used for bedding or securing glass and for separating glass from the frame.

Glass:
An inorganic and transparent material composed of silica (sand), soda (sodium carbonate), and lime (calcium carbonate) with small quantities of alumina, boric, or magnesia oxides. Glass is most often placed in categories based on the amount of heat used in its manufacturing process. Annealed (Float) Glass is made with the least amount of heat, followed by Heat Treated (or Strengthened) Glass, and then by Tempered Glass. "Common" glass may also be referred to as "flat", "window" or "plate" glass and are the types most commonly used for building windows, tabletops, and the manufacture of mirrors. The modern method of glass production can be credited to the Pilkington famiy with the advent of the float glass process; approximately 90% of today's glass is manufactured using the float process.

Glazing:
Glass used as a covering.

Glazing Bead:
A strip of wood, metal or other suitable material attached to the glazing surround to fix the position of glass.

Glazing Compound:
Soft material used for the glazing of glass.

Glazing System:
A glazing system is comprised of the frame/framing system, the glazing materials (such as gaskets, sealant, tapes), and the glass itself.

Insulating Glass:
Insulating glass is a multi-glass combination consisting of two or more panes enclosing a hermetically sealed air space.

Insulating Strip:
A material used to protect the edges of the glass from rigid contact with non-resilient material.

Interior Glazes:
Glass used inside buildings.

Interlayer:
The term applied to the material used in laminated glass to bond the glass leaves together.

Inner Pane:
The pane of a double-glazed unit which faces the interior of a building.

Laminated Glass:
Laminated glass is a combination of two or more glass sheets with one or more interlayers of plastic (PVB) or resin. In case of breakage, the interlayer holds the fragments together and continues to provide resistance to the passage of persons or objects.

Light or Lite:
A window, or a term for a pane of glass within a window.

Mil:
One thousandth of an inch; 0.0254 millimeter.

Pane:
A sheet of glass, or a compartment of a door or window consisting of one sheet of glass in a frame.

Reflectance:
Measures the percentage of solar energy and visible light that are being reflected by the window film. The ratio of reflected radiant energy to incident radiant energy. Highly reflective films offer high heat rejection capability.

Refraction:
The deflection of a ray of light from a straight path as it passes an oblique angle from one medium to another, such as from the air to glass.

R-Value:
A measure of the resistance of a glazing material or fenestration assembly to heat flow. The inverse of the U-Factor (R=1/U), it's expressed in units of hr-sq ft-degrees F (Fahrenheit) / Btu (British Thermal Unit). The higher the R-Value, the greater the window's resistance to heat flow and higher the insulating value.

Safety Glass:
A generic term for glass that is less subject to breakage or sharding, having been strengthened or reinforced.

Sandblasting:
A special glass treatment in which sand is sprayed at high velocities over the surface of the glass.

Sealant:
A flexible material for sealing.

Sealed Double Glazed Unit:
A combination consisting of two glass panes enclosing a hermetically sealed air space.

Sealed Multiple Glazing Unit:
A combination consisting of several glass panes enclosing hermetically sealed air spaces.

Shading Coefficient:
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 were made of clear, non-shaded double strength window glass. The lower the shading coefficient number, the better the solar shading qualities of the glazing system. Shading coefficient defines efficiency of the glazing system and is expressed as a number between 0 and 1.

Single Glazing:
Window or door with a single glass lite.

Single-Strength Glass:
A term used to describe glass with a defined thickness (2.16-2.57 mm).

Spalling:
The spray of window glass fragments and razor sharp large shards of glass that occurs after a blast impact that cause a great deal of human casualties and property damage. Small fragments of glass that are ejected from the surface of a laminated glass sheet when the opposite surface is impacted.

Spectrally Selective Glazing:
A special coated glass that is transparent to some energy wavelengths and reflective to others.

Tempered Glass:
A type of glass that is approximately four to five times stronger than common annealed glass that breaks into small pieces or fragments instead of large shards when broken. Tempered glass is strengthened by re-heating it to just below the melting point, then suddenly cooling it. Is resistant to the effects of temperature changes and cannot be re-cut after completion of the tempering process.

Tinted Interlayer:
A colored plastic or resin sheet between two or more panes of glass.

Total Solar Energy Rejected:
Measures a window film’s ability to reject solar heat in the form of visible light and invisible infrared radiation.

Total Solar Reflectance :
The ratio of total solar energy that is reflected outward by the glazing system to the amount of total solar energy falling on the glazing system. On filmed windows this reflectance is a function of the side of the film facing the window surface. This value is usually expressed as a percent.

Total Solar Transmittance:
The ratio of the amount of total solar energy in the full solar wavelength range (300-2,100 nanometers) that is allowed to pass through a glazing system to the amount of total solar energy falling on that glazing system. Value is usually expressed as a percent.

Transmittance:
Measures the percentage of solar energy and visible light (daylight) that passes through a glazing system or the percentage of radiation that can pass through glazing. All solar control films reduce visible light transmission in order to provide solar heat control. Lighter films tend to transmit higher levels of solar energy and visible light while darker and more reflective films have lower transmittance levels.

Transom:
A window, usually small, located above a door or above another window.

U-Value or U-Factor: (Insulating Value)
A measurement of heat transfer due to outdoor/indoor temperature differences; a measure of the rate of non-solar heat loss or gain through a material or assembly; describing the dealt loss (or gain) through a material. The lower the U-Value, the less heat transfers. The overall heat transfer coefficient of a glazing system, the U-Factor, is a measure of the heat transfer that occurs through the glazing system, and its outer and inner surfaces. This value is a function of temperature, and is expressed in BTU per square foot per hour per degree Fahrenheit (BTU/sq.ft./hr.degrees F). The lower the U-Factor, the better the insulation qualities of the glazing system.

Ultraviolet Light (UV):
The invisible rays of the electromagnetic spectrum that are outside of the visible spectrum at its short-violet wavelength end. UV rays are contained in sunlight and have been found to cause fading to carpets, fabrics, and paint finishes.

Ultraviolet (UV) Transmittance:

The ratio of the amount of total UV solar energy (300-380 nanometers) that is allowed to pass through a glazing system to the amount of total UV solar energy falling on the glazing system. Ultra-violet is one portion of the total solar energy spectrum that greatly contributes to fading and deterioration of fabric and furnishings.

Visible Light:
That portion of the electromagnetic spectrum that produces light that can be seen, with wavelengths ranging from 380 to 720 nanometers.

Visible Light Reflectance:
The percentage of the total visible light that is reflected by a glazing system.

Visible Light Transmittance:
The ratio of the amount of total visible solar energy (380-780 nanometers) that is allowed to pass through a glazing system to the amount of total visible solar energy falling on the glazing system. Value is usually expressed as a percent. Glare is influenced by visible light transmittance through a glazing system.

Window:
A glazed opening in an external wall of a building; an entire unit consisting of a frame sash and glazing along with any operable elements or hardware.

Wired Glass:
A product in which a wire mesh has been inserted during production. It has an impact resistance similar to that of normal glass, but in case of breakage, the mesh retains the pieces of glass.


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