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PROSTARS Home > Repair & Replacement Guide >Auto Glass Glossary

Auto Glass Glossary

The PROSTARS Auto Glass Glossary covers general terms that may assist you in reading and understanding about auto glass and making informed decisions about how to best handle your auto glass damage needs.

Don't see a term you're looking for? Contact your local PROSTARS glass specialist and they'll put their knowledge and skills to work for you.

The following are general terms that may be helpful to you in understanding the automotive glass repair/replacement process. The content provided is for informational purposes only. Information is subject to change without prior notice.

Last Updated: 12/03/2008

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A Back to top
A-Pillar:Roof support member adjacent to the windshield.
Acetic Acid:An acid that can be corrosive to zinc, steel, and other types of aluminized panels.
Acetone:A colorless, volatile, water-soluble, flammable liquid made from either alcohol or by bacterial fermentation of carbohydrates; used in paints and varnishes, as a general solvent, and in chemical manufacturing.
Adhesion:The clinging or sticking together of two surfaces. The state in which two surfaces are held together by forces at the interface.
Adhesive:Any subtance -- inorganic, natural, or synthetic -- that is capable of bonding other substances together by surface attachment.
Airbag:A passive restraint system that uses an explosive device to inflate a bag at a high rate of speed. The bag inflates with a gas and then quickly deflates when a vehicle occupant is thrown into it. Airbags are typically mounted in the steering wheel on the driver's side of the vehicle and in the dashboard on the passenger's side. Some vehicles are also equipped with airbags for side impact collisions as well.
Allen Wrench:A six-sided wrench.
Anneal:A controlled process for making glass stronger and less brittle in which the glass is heated and then cooled.
ANSI Standards:Health and safety standards set by the American National Standards Institute.
Antenna:A conductor by which electromagnetic waves are sent out or received, consisting commonly of a wire or set of wires.
Antenna Windshield:Windshield with a radio antenna built in. Older antennae were constructed with wires embedded in the glass, but the current technology of using a thin metal coating as the antenna circuit delivers improved radio reception. Although these windshield antennae can be difficult to see, they can usually be found on vehicles that have no other visible antenna mounted on the outside.
ARG/AGR:An abbreviation of the aftermarket auto glass industry. Automotive Replacement Glass/Aftermarket Glass Replacement.
Auto Glass Repair:The act of repairing a break in a windshield or other laminated auto glass part, rather than replacing it. Auto glass repair is a process that removes the air from the break and fills it with a curable, optically matched resin. Same as windshield repair.
Auto Glass Technician (AGT):Level of certification designated by the National Glass Association (NGA). Designated by a minimum of six months work experience in the auto glass industry serving in the position of auto glass installer.
Autoclave:A large pressurized oven used in the glass industry to heat layers of polyvinyl plastics and glass to form laminated glass.
B Back to top
B-Pillar:Roof support member immediately behind drive door lite.
Back-Lite:The rear window of a vehicle.
Batch:The raw materials mixed and ready to be fused into glass.
Bead:A sealant or adhesive compound after application in a joint, irrespective of the method of application, such as a urethane bead applied to a pinchweld. A bead looks like a ribbon of adhesive rather than a round drop of adhesive.
Belt Molding:A rubber molding between the inner and outer panels of a vehicle door through which the door glass is raised and lowered.
Bit Brace:A hand tool that is used to drill holes.
Bite:Amount of adhesive overlap between the pinchweld and windshield.
Block (setting):A small piece of neoprene or other suitable material used to position the glass in the frame or opening.
Bond:The attachment at an interface between substrate and adhesive or sealant.
Bond Strength:The force, per unit area, necessary to rupture a bond.
Bull's Eye:Impact damage to laminated glass that is marked by a clean, separated cone in the outer layer of the glass
Buttering:The application of sealant to the surface of substrate before placing another substrate in position.
Butyl:An adhesive used in earlier model vehicles for glass retention. It is a petroleum product that requires no curing or hardening.
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Cap Bead:A finished bead applied at the top of an installation.
Carbide:A hard binary compound of carbon and a more electropositive element. Used to coat and reinforce the tips of tools to extend the life of the tool.
Catalyst:The substance added in small quantities to promote a reaction, while remaining unchanged itself.
Caulk (noun):A sealant with a relatively low movement capability.
Caulk (verb):To fill the joints with a sealant.
Caulking:A resilient mastic compound often having a silicone, bituminous, or rubber base; used to seal cracks, fill joints, prevent leakage, and/or provide waterproofing.
Cerium Oxide:A compound that is used to polish scratches out of windshields.
Channel Tape:A cork and rubber composition material used to secure door glass and to fill channels.
Channel:A piece of U-shaped metal lined with felt; used to reduce glass breakage and noise and to correct alignment of moveable glass parts.
Chip:Damage to the edge or surface of glass resulting in flake(s) or chunk(s) being removed.
Circle Cutters:Cutters that have a vacuum base that attaches directly to the glass. The adjustable arm holds a ruler set to the radius of the desired circle.
Clips:Devices which hold decorative chrome to the vehicle body or hold moldings to the vehicle body.
Cohesion:The ability of a sealant or adhesive to hold itself together. The internal strength of an adhesive or sealant.
Cohesive Failure:Adhesive failure indicated by hardened material on both substrate surfaces.
Combination Break:A break in a windshield involving more than two types of breaks.
Combustible:Any liquid that will ignite at or above 100 degrees Fahrenheit, but below 200 degrees Fahrenheit.
Compatibility:Refers to the reaction a sealant has on another sealant or on another material.
Compression Gasket:A system that uses a soft gasket on one side of the glass and a firm, dense gasket called a wedge on the other.
Contaminant:A substance, liquid or solid, which is present in a break. Contaminants must be removed from a break before a repair can begin.
Coolant:A liquid used to cool and lubricate glass while it is being cut or ground with a tool to prevent hot spots or fracturing of the glass.
Corrosion:The chemical reaction of air, moisture, or corrosive materials on a surface; also called oxidation. The process of wearing away the surface of a solid.
Cosmetic Blemish:A defect in the appearance of a vehicle. Includes torn upholstery, scratched paint and resin spills.
Cosmetic Surface:A surface that is finished or decorated to improve its appearance. Includes such things as paint, glass and upholstery.
(Stress) Crack:Any crack extending from an edge without an impact point.
Crazing:A phenomena that occurs to plastic when it is exposed to either harsh weatherization, U.V. light or force bending beyond the recommended minimum radius.
Creep:The deformation over time of a body under constant load.
Cullet:Uncontaminated (clean) broken glass that is recycled into the batch to make new glass.
Cure Time:The time required for a chemical or material to dry or set at a given temperature and humidity. Cure time varies with the type of material used and the thickness of the application.
Curing Agent:A chemical which is added to effect a cure in a polymer.
Curing:A process of drying and hardening over a given period.
Cutout:The process of cutting out and removing a windshield.
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Delamination:The failure of the bond between layers, as when windshield glass separates from the laminate, or when paint peels from the substrate beneath it.
Denatured Alcohol:Alcohol to which an unwholesome substance has been added to make it unfit for drinking. The denaturing substance does not affect the alcohol's usefulness for other purposes.
Density:The mass per unit volume of a substance under conditions of pressure and temperature.
Diamond Cutters:Specially shaped diamond to score glass.
Ding:A term often used by the public to refer to a stone damage to a windshield.
Double Seal Units:Insulating glass with two materials used to form the seal of the glass.
Drag Co-Efficient:The mathematical expression of the retarding force exerted by air upon a body.
Drilling:The use of a drill to gain access to a tight break.
Dry Glazing:A method of securing glass in a frame by use of a dry, preformed, resilient gasket without the use of a compound.
E Back to top
Edge Crack:Any crack on the windshield that that extends to an edge.
Elongation:A property of urethane adhesive: An increase in length expressed numerically as a fraction or percentage of initial length.
Emery:A granular mineral substance used for grinding and polishing glass.
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Fast Cure Urethane:A faster hardening adhesive. The term "fast" is relative to the surrounding temperature and humidity. Curing time is faster than for normal adhesives.
Federal Motor Vehicle Safety Standards (FMVSS):A series of standards required of the automobile manufacturers by the Federal Government. All new vehicle models must meet these standards before they are allowed to be sold in the United States.
Frit:The painted band around the perimeter of auto glass parts.
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Gasket:A channel or frame, usually made of rubber, which holds glass parts in place.
Glass Composition:Refers to the chemical and physical makeup of glass type.
Gravity Bending:A means of curving glass by heating and draping over a mold to achieve the desired curvature.
H Back to top
Half Moon:Damage to a windshield that has a half-circle separation around the impact point. It is similar to a bull's eye.
Headliner:The fabric which lines the roof of a vehicle's passenger compartment.
Heated Backlite:A backlite with defroster grid lines printed on the glass to defrost or defog the backlite.
Heated Windshield:Windshield with an invisible heater circuit on the full surface of the windshield for defrosting the glass. Vehicles equipped a heated windshield will not require noisy air vents on the dash to blow defrosting air on the windshield surface.
Heated Wiper Park:Heated area across the bottom of some windshields. In vehicles equipped with this feature, the heated wiper park can be turned on to melt ice that has accumulated at the bottom of the windshield where the windshield wipers sit while idle.
Hot Melt Butyl:An insulating glass edge sealant used during manufacturing.
I Back to top
I-CAR:An international, not-for-profit training organization formed by the collision industry in 1979.  All I-CAR activities and resources focus on helping the industry achieve a high level of technical training.
Impact Resistance:The measurement by which it is determined how much impact is required for breakage.
Impact Site:The actual location on the outside layer of glass, where it was struck by an object (usually a stone). Typically a small piece of glass is missing.
Impact:This is the most common break. It occurs when an object hits the windshield.
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Laminate:Vinyl inner layer of laminated glass.
Laminated Glass:A type of safety glass that has a layer of plastic bonded between layers of glass. Laminated glass is used mainly for windshields.
Long Crack:A crack on the windshield of more than 6 inches (15.24 cm). See also: Crack
M Back to top
Master Auto Glass Technician (MAGT):Level of certification designated by the National Glass Association (NGA). Designated by a minimum of five years work experience in the auto glass industry serving in the position of auto glass installer and prior achievement of Senior Auto Glass Technician Level certification.
Mobile Unit:A vehicle, usually a van or light truck, properly equipped with repair and safety equipment and tools, driven to an auto glass repair customer's home or place of business. Glass repairs are made from the vehicle.
Molding or Chrome Release Tool:Tool used to remove molding clips from a windshield or back lite.
N Back to top
NGA:National Glass Association, the largest trade association specifically for the North American glass industry. NGA represents the architectural, automotive and specialty glass segments of the industry. Its mission is to provide information and education and to promote quality workmanship, ethics and safety in the glass industry.
NGA-Certified:Installation specialists who have met the certification requirements of the National Glass Association. The two levels of certification are:
Nitrile Gloves:Surgical-grade, latex-free synthetic rubber gloves used to prevent oils and dirt from the hands contaminating glass surfaces. Nitrile gloves protect hands from harmful primer, prep and adhesive chemicals.
O Back to top
OEM:Abbreviation for "original equipment manufacturer." Refers to original and new parts.
One-Part Sealants:Sealants that require no premixing.
One-Part Urethane:An adhesive used in auto glass replacement that has only one component.
Open Time :The time interval between the application of an adhesive and when it becomes no longer workable.
P Back to top
Passive Restraint System:A system of protection that requires no effort on the part of the occupants of a vehicle, i.e., self-retracting seat belts, airbags.
Perimeter:The outside edge of the windshield where the urethane is applied.
Pinchweld (aperture):The metal surface in an automobile opening.
Pinchweld:The ledge surrounding the opening of the vehicle that supports the windshield. The urethane adhesive attaches to the glass on the pinchweld.
Pit:The impact point from which, typically, a small piece of glass is missing.
PPG:Formerly an acronym for Pittsburgh Plate Glass, now changed to PPG Industries, Inc., an automotive glass manufacturer.
Prep:A cleaner or a product that enhances an adhesive. A prep is usually applied to the glass prior to the primer.
Pressure Sensitive Adhesive:Adhesive which retains tack after release of the solvent, so that it can be bonded by simple hand pressure.
Primer:A material used to prepare metal bonding areas and ensure a strong bond between the glass part and the adhesive.
Primerless Urethane:A type of urethane adhesive that requires no primer on the glass surface. Metal primers may be necessary.
Pump Gun:A device used for pumping sealants and adhesives.
PVB:Acronym for Polyvinyl Butyrate, the vinyl interlayer of laminated glass.
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Quarter Glass:Glass part on the side of the vehicle, closest to the backglass. Named for its location above the vehicle's quarter panel.
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Rain Sensor:Sensor mounted on the inside surface of the windshield, typically under the rear view mirror. In vehicles equipped with a rain sensor, the windshield wipers can be set to automatically come on when this sensor detects rain on the windshield's outside surface.
Regulator:A manually- or power-operated device which rolls a vehicle's window up and down.
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Safety Glass:A general term used for either laminated or tempered glass. Only glass which has been laminated, however, can specifically be called laminated safety glass.
Salvage Part:A part, removed from a vehicle being scrapped, that is intended to be used as a replacement part.
Sealant:A substance used to seal between meeting surfaces to make weathertight. No to be confused with adhesive, which provides a structural bond. Typically, a material of low strength.
Shadeband:Darkened, translucent band across the top of some windshields for reducing glare from the sun. Typically blue, green or grey in color.
Shard:A sharp piece or fragment of glass.
Short Crack:A crack on the windshield of 6 inches (15.24 cm) or less.
Sidelite:Passenger car side windows.
Solar Coated Windshield:Windshield with a special coating to reflect solar energy and keep the vehicle interior cooler and more comfortable. These windshields typically have a pinkish hue to them.
Star Break:Damage to a windshield marked by various-sized cracks radiating from the central impact point.
Stone Break:A break on the outer layer of a laminated windshield. Typical stone breaks are star breaks, bulls eyes or combination breaks.
Straight edge:A piece of material with a straight edge for testing straight lines and surfaces or drawing straight lines.
Stress Cracks:Cracks resulting from unusual forces acting on the glass body. Generally forces created along edge of glass.
Structural Integrity:Your vehicle's ability to retain roof strength and structure during a rollover accident.
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Tempered Glass:A strong, break-resistant type of safety glass that, if broken, shatters into small granular pieces.
Tempering:Strengthening glass with heat.
Two-Part Adhesive/Urethane:A type of adhesive that has two component parts: Hardener and resin. In auto glass adhesives, there are two-part urethanes and two-part adhesives. Although they are different chemically, they do have similar performance characteristics.
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Uniform Bead:A consistent width and appearance of a substance (adhesive) applied to a surface.
Urethane Breakdown:Results when urethane is exposed to ultra-violet light. Urethane breakdown appears as a chalky black powder on the surface of the hardened adhesive.
Urethane Bed:The area along the pinchweld where the bead of urethane is applied.
Urethane:A colorless or white crystalline compound used to bond windshield to metal.
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Vaccuum Cup:A tool used for picking up glass.
VIN Plate:A permanently installed plate, displaying the vehicle identification number, which is viewable through the windshield from outside the vehicle.
VIN:Vehicle Identification Number. A 17-digit combination of letters and numbers unique to each vehicle. The VIN is embossed onto a small plate attached to the dashboard at the bottom left side of your windshield.
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Windshield Repair:The act of repairing a break in a windshield, or other laminated auto glass part, rather than replacing it. Windshield repair is a permanent process that removes the air from the break and fills it with a curable, optically matched resin. Same as auto glass repair.


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