Glossary of Terms
In the manufacturing of float glass, it is the process of controlled cooling, which is done in a lehr to prevent residual stresses in the glass.
An apparatus used as a controlled heating/cooling instrument.
American Society for Testing and Materials
A vessel that employs high pressure heat used to produce a bond between glass and PVB or urethane sheet, creating a laminated glass product.
Flat glass that is curved into shapes while still hot.
The process of edge finishing glass to a beveled angle.
A noticable impefection in glass.
Bubbles in a coating film that forms during the heat treating process.
Bow (or Warp)
A curve, bend or other deviation from flatness in glass.
The resulting pattern formed by the cracks in glass when broken. Also called the fracture pattern.
Breather (Tube) Units
An insulating glass unit with a tube in the unit's spacer to accommodate pressure differences in shipping, due to the change in elevation. These tubes are sealed at the jobsite prior to unit installation.
A gas pocket in the interlayer material or between the glass. In float glass, a inclusion greater than 1/32" in diameter.
The extreme lateral edge of the ribbon, as drawn in the float glass manufacturing process.
Bullet Resistant Glass
The multiple lamination of glass. Glass and plastic that are designed to resist penetration from small fire arms.
The installation of glass where the vertical glass edges are without structural supporting mullions.
Capillary Tube Units
(See Breather Tubes)
A term sometimes used for tempered glass.
Tension stresses within the center portion of heat-treated glass.
An inorganic and non-metallic coating used to be fused to a substrate.
Very small cracks in flat glass usually at the edge.
Chemically Strengthened Glass
Glass that has been heat treated from ion-exchange to produce a compressive stress layer at the treated surface area.
An imperfection due to breakage.
Moisture on the surface of an object caused by warm moist air coming into contact with a colder surface.
A method of making flat glass. Blowing a large bulb, opening it up, and spinning it flat.
A lightly pitted area on the glass surface, resulting in a dull gray appearance.
Broken glass, extra glass from a previous melt or the edges that are trimmed off glass to size. Cullet is one of the essential ingredients in the raw batch in glass-making, it facilitates the melting process.
Glass cut to a specified width and length.
Scoring glass with a diamond, steel wheel or other alloy wheel and breaking it along the score.
A manufacturing process of flat glass. Molten glass is blown and drawn into the form of a cylinder, which is subsequently split longitudinally, reheated, and flattened.
Deflection (Framing Member)
The amount of bending movement of any part of a structural member perpendicular to the axis of the member under an applied load.
Deflection of Glass
The amount of bending of the center of glass.
Specific pressure a product is designed to withstand.
The cubical pattern of a fracture in fully tempered glass.
The scattering and dispersing and the tendency to eliminate a direct beam of light.
Deep, short scratches.
A small particle of foreign material imbedded in the surface of flat glass.
Alteration of viewed images, caused by the variations in the flatness of glass.
Two lites of glass, separated by an air space, to improve insulation against heat transfer and sound transmission. Insulating glass units contain air between the glass which is thoroughly dried and sealed, eliminating condensation and providing superior insulation.
Double Glazing Unit
Two panes of glass separated by a permanently sealed air or gas cavity.
Double Strength Glass
Float glass, approximately 1/8" (3mm) thick.
Glass produced by a continuous drawing operation.
Compressive stresses at the edge of heat-treated glass.
A specified finish to the edges of glass. Sometimes called Edgework.
Grinding the edge of flat glass to the desired shape or finish.
The measurement of a surface's ability to emit long-wave infrared radiation.
To alter the surface of glass. Usually by hydrofluoric acid or other caustic sources. Permanent etching of glass can occur from long term, high alkali contact.
Any debris resulting from the processing and fabricating of glass prior to the tempering process.
Any glass panel, window, door or skylight on a building.
A term that describes float glass, sheet glass, plate glass, cylinder and rolled glass.
A pool of molten metal, usually tin, in which molten glass is drawn into a flat sheet.
Glass formed on a bath of molten tin. The surface in contact with the tin is known as the tin surface. The top surface is known as the air surface.
An ingredient that reduces batch melting temperature.
Glass in particulate form.
Surface treated to simulate frost.
Fully tempered glass
Flat or bent glass that has been heat-treated to a high surface and edge compression to meet ASTM C 1048 Standards. Fully tempered glass, if broken, will fracture into many small cubical pieces, known as diceing. Fully tempered glass is approximately four times stronger than annealed glass of the same thickness.
Glass Association of North America.
Gas-Filled Insulated Glass Units
Insulating glass units with a gas in the air space to increase the unit's sound and insulating valve.
A round or elongated bubble in glass.
A hard brittle substance, usually transparent, made by fusing silicates, soda ash and lime stone, under high temperatures.
A general term used to describe glass, panels, etc. Also the process of installing glass or panels into a prepared opening in windows, door panels, partitions, etc.
Glazing Select Quality
This represents the float glass supplied when quality is not otherwise specified. (Typically q^3 from ATSM C 1036 Standard.)
The degree of shine or luster on the surface of glass, ceramic enamel or ink.
Glass that absorbs a significant amount of solar energy.
Glass able to withstand high thermal shock, usually because of its low coefficient of expansion.
Flat or bent glass that has been heat-treated to a specific surface and edge compression to meet the requirements of ASTM C 1048. Heat-strengthened glass is approximately two times as strong as annealed glass of the same thickness. Heat-strengthened glass is not considered safety glass, because it will not dice like fully tempered glass.
Term used for both fully tempered glass and heat-strengthened glass.
Those manufacturing operations dealing with hot glass, which are melting, forming, and annealing.
A foreign solid or gas within the glass matrix.
Insulating Glass Unit
Two or more pieces of glass spaced apart and hermetically sealed to form a single-glazed unit, with an air space between each lite. Commonly called IG units.
Any material used to bond two lites of glass together to form a laminate.
A display of rainbow-like colors in glass.
International Window Cleaning Association.
An abrupt deviation on flat glass most commonly found near the edge of heat-treated glass.
An imperfection in the form of a vitreous lump.
Two or more pieces of glass permanently bonded together with interlayers.
Pieces of glass bonded together at their edges. Usual with soldered lead.
A long, tunnel-shaped oven for annealing glass, usually by a continuous process for slow cooling.
Calcium oxide or a mixture of calcium oxide and magnesium oxide.
Calcitic limestone or dolomitic limestone.
Another term for a pane of glass.
Low-emissivity or Low-e
A low rate of emitting absorbed radiant energy.
The glass melting assembly, including the melter, regenerators, flues, refiners, forehearths, channels, throats, etc.
Spreading or creeping of a compound into adjacent surfaces.
Horizontal or vertical bars that divide the glass area into smaller lites of glass.
National Glass Association.
A surface cavity formed by a gaseous inclusion.
Roughness or waviness on the surface of glass which resembles the skin of an orange in texture.
Rolled glass with a pattern imprinted on one or both sides. Usually used for light control on bath enclosures or decorative glazing.
Pilkington Float Glass Process
The process of making flat glass with a continuous pour of glass onto a molten tin bath.
Pittsburgh Sheet Process
The method of making sheet glass by drawing it vertically upward from a bath.
Flat glass formed by the rolling process, then ground and polished on both sides.
A device for examining the amount of strain in a glass sample.
A thin Low-e coating applied to the hot surface of glass when manufactured.
A relative term describing the degree of excellence with regards to a product, process or service.
To rapidly cool.
A pattern of dark shadows commonly refered to as the Quench Pattern.
The thermal resistance of a glazing system.
A glass batch without cullet.
A glass batch made of only cullet.
Glass with a metallic coating to reduce solar heat gain.
A continuous length of glass in process.
Roller Distortion or Roller Wave
A waviness resulting in horizontal heat-treated glass, as a result of glass being transported through the furnace on rollers.
The opening in a wall in which a door or window is installed.
Small scratches in glass, generally caused during shipping.
Flat or bent glass that is heat treated or laminated, and if broken would not cause serious injury.
To penetrate the surface of glass with a cutting device, such as a glass cutter.
Coating applied to glass surfaces to reduce scratching effects.
Any marking or tearing of the glass surface.
Sealed Insulating Glass Units
(Same as "Insulating Glass Unit")
To grind or sand the sharp edges of a piece of glass, usually with a belt or wheel.
Small bubbles in float glass, less than 1/32" in diameter.
A devise used for inspecting glass for distortion or other defects.
A term used to identify the appearance of the cut edge of glass.
Flat glass made by continuous drawing in the vertical direction.
Shore "A" Hardness
Measurement of hardness by means of a Durometer Hardness Gauge.
The process of appling silver to the back of mirrors.
To cut a piece of glass to a specific size.
A glass or plastic window, usually installed on a roof of a building.
Streaked areas in glass appearing with slight discoloration.
Sodium oxide. A carbonate of sodium.
Soda Lime Glass
An abbreviation for soda-lime-silicate glass.
Glass compositions in the most common flat glass made today.
Solar Control Glass
Tinted or coated glass that reduces solar heat gain through a glazed product.
Panel of a wall located between vision areas which conceal structural columns, floors and walls.
Discoloratin of glass.
Crystalline inclusion imbedded in the glass.
A glass panel placed on the outside of an existing window as an extra protection from the elements.
A specific iridscent pattern or darkish shadow that appears under certain polarized lighting conditions, also known quench marks. The stress pattern is caused by localized stresses from the rapid air cooling on a tempering operation, such as heat-treated glass.
A term to indicate relative thickness in flat glass.
Flat glass between 0.115 and 0.134 in. thick.
Flat glass between 0.085 and 0.101 in. thick.
Any tension or compression existing in the glass, usually as a result of incomplete annealing.
An imperfection in glass resulting from a large grain of sand or foreign material.
A process in which glass is transported or installed by vacuum.
Surface stresses in heat-treated glass, resulting from rapid cooling of glass surface to produce compresssive stresses at the surface.
An small imperfection in the surface of glass.
The amount of residual stress in annealed glass.
A term for glass subjected to heat treatment, followed by rapid cooling, to produce a compressive surface layer.
The inner layer of heat treated glass.
The ability of glass to withstand thermal shock.
The change in temperature, sometimes caused by a shadow, imposed on a glass surface.
The stress produced by the change in temperature within a glass body.
Small, surface indentations along one edge of vertically-tempered or heat-strengthened glass, resulting from the tongs used to transport the glass through the heat treating process.
A term sometimes used by foriegn manufactures to identify heat-treated or fully tempered glass.
A furnance door that opens vertically.
The measurement of heat transmission due to the thermal conductance.
Windows holding glass in place with extruded vinyl.
Sodium silicate glass that is soluable in water.
Weeps or Weep Holes
Drain holes or slots in the framing of windows to prevent accumulation of condensation or water.
An opening constructed in a wall to admit light or air, usually framed with glass and sometimes mounted to permit opening and closing.
Flat glass with wire mesh embedded in the glass.