Article by Iowa Auto Glass
Acute Area
The area of the windshield directly in front of the driver’s eyes, beginning just above the steering wheel. It measures approximately 8 1/2 inches high by 11 inches wide. This area is used as the standard for the driver’s critical vision area by most auto glass shops and insurance companies in North America.
Adhesion
The clinging or sticking together of two surfaces. The ability of an adhesive to stick to a surface.
Adhesive Failure
Adhesive failure indicated by the material’s failing (pulling loose) at the surface of the substrate. Similar to “scotch” tape peeling off a plastic substrate.
Adhesive
Any substance that is capable of bonding other substances together by surface attachment. In an auto glass replacement context, it is a high-strength polyurethane material unless otherwise specified.
Aerodynamics
The branch of physics that deals with the motion of a solid body through air and other gases.
Aging
The progressive change in the chemical and physical properties of a sealant or adhesive over time.
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. It is mounted in the steering wheel on the driver’s side of the vehicle and in the dashboard on the passenger’s side. There are also airbags installed for side impact collisions. Some passenger-side airbags use the windshield to position the deploying bag.
Air Side
The upper surface of the glass, also referred to as the score side.
Annealing
The controlled process of cooling glass after manufacturing to strengthen glass and make it less brittle.
Anneal
The controlled process for making glass stronger and less brittle in which the glass is heated and then cooled.
A-Pillar/Post
The forward or windshield pillars on a car that support the windshield and the front portion of the roof.
Antenna Glass
In some late-model vehicles the radio antenna is incorporated into the windshield or the back-light (rear window).
Anti-Lacerative Glass
Glass that has a resilient layer (PVB) added to the inner surface. It prevents passengers from coming into contact with broken glass edges on the inner surface in the event of a collision.
ARG/AGR
An abbreviation of the after market auto glass industry. Automotive Replacement Glass/After market 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 permanent process that removes the air from the break and fills it with a curable, optically matched resin. Same as windshield repair.
Back-Light
Passenger car rear window made of tempered or laminated glass. Vehicles with convertible tops have windows made of plastic or tempered.
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.
Bite
Amount of adhesive overlap between the pinchweld and windshield.
Block (setting)
A small piece of neoprene or other suitable material used to position glass in the frame.
B-Pillar/Post
The side or doorposts connect the sills and the roof, providing the car’s roof support. On a true hardtop designed car-a term derived from hardtop convertible-these pillars are missing, leaving uninterrupted glass along the sides of the car.
Bullet-Resistant Glass
Glass that consists of multiple layers of laminated glass. It is designed to resist penetration from medium to super-power small arms and high-power rifles.
Bull’s Eye
Impact damage to laminated glass that is marked by a clean, separated cone in the outer layer of the glass.
Butyl
An adhesive used in earlier model vehicles for glass retention. It is a petroleum product that requires no curing or hardening. Butyl is available in rolls of approximately 15 feet.
Butyl Rubber
A copolymer of isobutene and isoprene. As a sealant, it has low recovery and slow cure, but good tensile strength and elongation.
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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 used in the replacement of commercial or residential glass.
Chemical Cure
Curing by chemical reaction. This usually involves the cross-linking of a polymer.
China Markers
A wax marker used to mark glass.
Chip
Impact damage to laminated glass that does not penetrate the outer light. Although glass is missing from the impact point, there is no trapped air in the damage.
Close-Cut Or Partial-Cut Installation
An installation method that leaves most of the existing adhesive bead/bed adhered to the metal frame and adds a small fresh bead of adhesive into which to set the glass. Some vehicle manufacturers do not recommend this procedure.
Coated Glass
Glass with a chemical film applied to one surface. The film can provide such enhanced performance characteristics as privacy, solar or mirror effects.
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 cured material on both substrate surfaces. The material itself failed (the body of the adhesive or sealant pulled apart).
Combination Break
A break in a windshield involving more than two types of breaks.
Compatibility
Refers to the reaction a sealant has on another sealant or on another material.
Compression
Pressure exerted on a sealant in a joint.
Compress
The act of pressing together or to force into a smaller space.
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.
Crack
An extended crack in a windshield from both sides of an impact point. There are several different kinds of cracks: Short crack: A crack on the windshield of 6 inches (15.24 cm) or less. Long crack: A crack on the windshield of more than 6 inches (15.24 cm). Edge crack: Any crack on the windshield that extends to an edge. Floating crack: Any crack on the windshield that does not extend to an edge. Stress crack: Any crack extending from an edge without an impact point.
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 that is added to affect a cure in a polymer.
Curing
A process of drying and hardening over a given period.
Dam
A product having several purposes: 1. A dam positions the glass in the opening while the adhesive cures. 2. A dam holds the liquid adhesive and prevents it from flowing into the interior of the vehicle. 3. A dam provides an esthetically pleasing site-line. 4. A dam acts as a sound barrier.
Damage
Same as break and crack.
Dauber
A disposable cotton applicator for applying primers and preps to the metal and glass bonding surfaces.
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.
Ding
A term often used by the public to refer to stone damage to a windshield.
Double Seal Units
Insulating glass with two separate seals used to form the seal of the glass.
Drop-Jaw Glass Pliers
Pliers used for breaking glass. They have a flat upper jaw and humped lower jaw.
Dry Glazing
A method of securing glass in a frame by use of a dry, preformed, resilient gasket.
Durometer
A blunt probe used to penetrate sealant that measures the shore hardness from 0 to 100.
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Edge Crack
Any crack on the windshield that extends to an edge. See also: Crack.
Elasticity
The ability of a material to return to its original shape after it has been stretched.
Elongation
Is the stretchability or flexibility of cured urethane. Urethane must have the right flexibility to absorb body flex and the stiffness to support glass.
Emery
A granular mineral substance used for grinding and polishing glass.
Encapsulated glass
A type of auto glass fabrication. Pre-assembled parts that contain hardware: moldings, fasteners, clips, or gaskets. Glass with a decorative molding around all or part of the perimeter. The encapsulation can also act as a channel guide. The molding (encapsulation) is actually part of the glass and can be removed only by cutting it off the glass.
Extrusion Failure
The failure, which occurs when a sealant is forced too far out of the joint.
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.
Fatigue Failure
The failure of a material due to rapid cyclic deformation.
Federal Motor Vehicle Safety Standards (FMVSS)
A series of standards required of the automobile manufacturers by the U.S. Government. All new vehicle models must meet these standards before they are allowed to be sold in the United States.
Filler Strip
A strip inserted into a rubber gasket after the glass is installed, forcing the gasket against the glass to form a seal and improve the grip. It is sometimes called locking a bead or spline.
Filler
Finely ground material added to a sealant or adhesive to change or improve certain properties.
Flexing
A method of gaining access to a tight break by flexing the glass back and forth, either with a tool or by hand.
Floating Crack
Any crack on the windshield that does not extend to an edge. See also: Crack.
Flowering
A flower petal effect around the outer edge of a repair. This is caused by the laminate detaching from the outer layer of glass.
Frit
The painted band around the perimeter of auto glass parts. Protects the urethane bead from UV degeneration.
Full Strip Installation
An installation method whereby the technician removes the existing bed/bead of adhesive from the vehicle frame. Approximately 1-2 mm of old adhesive remains. The technician applies new/fresh adhesive on top, and then sets the glass into the fresh adhesive.
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Gasket
A seal, usually of rubber, that holds a piece of auto glass to the vehicle body. There are various sizes and shapes of glass part gaskets, depending on vehicle design.
Green Strength
A term used by some adhesive manufacturers to describe initial strength of an adhesive.
Gun-Grade (gunnable sealant)
Sealant that can be applied with a manual-caulking gun.
Half Moon
Damage to a windshield that has a half-circle separation around the impact point. It is similar to a bull’s eye.
Hand Seamer
A hand tool used to seam the edge of glass and plastic.
Headliner
The fabric that lines the roof of a vehicle’s passenger compartment.
Heat Strengthened Glass
Similar to tempered glass, it is made by heating annealed glass, then cooing it more slowly than tempered glass.
Heated Urethane
A type of adhesive that is heated to a prescribed temperature before application. The heat pre-cures the adhesive faster, so the car can be released sooner.
High Modulus
High modulus is a rigidity requirement of cured adhesive. It provides extra strength to resist torsional twisting.
Hot Melt Butyl
An insulating glass edge sealant used during manufacturing.
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Impact
This is the most common break. It occurs when an object hits the windshield.
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.
Lami
Another name for laminated glass (see laminated glass).
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.
Lap Joint
A joint in which the component parts overlap so that the sealant or adhesive is placed into shear action.
Lap Shear Strength
The strength demonstrated by the diagonal pull of two substrates until adhesive failure. The name comes from the lap joint created by the test samples and the shear action used to pull the samples apart.
Legs
Short cracks that emanate from a break.
Light Transmittance
The percentage of visible light able to pass through the glass.
Lite
A term for a pane or a finished piece of glass.
Load Distribution
The specific placement of a supported weight or mass in a given area.
Long Crack
A crack on the windshield of more than 6 inches (15.24 cm). See also: Crack.
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Mobile Unit
A vehicle, usually a van or light truck, properly equipped with repair, replacement and safety equipment and tools, driven to an auto glass repair customer’s home or place of business. Repairs are made from the vehicle.
Modulus
The ratio of strength to stress.
Neoprene
A synthetic rubber having physical properties closely resembling those of natural rubber but not requiring sulphur for vulcanization. Extremely good weather resistance (both heat and cold) with ultraviolet stability.
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OEM
Abbreviation for “original equipment manufacturer.”
One-Part Urethane
An adhesive used in auto glass replacement that has only one component.
Opacifier
A material, either film or liquid, that is applied to the back of a piece of glass to act as a light shield.
Open-Celled
As in “Open-celled foam.” Foam extrusions can have the body contain connecting open cells. This allows air to pass through the foam to promote adhesive cure.
Open Time
The time interval between the application of an adhesive and when it becomes no longer workable.
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.
Personal Protective Equipment (PPE)
The safety gear worn by an auto glass repair technician. It includes nitrile gloves, safety/U-V glasses, dust and mist mask (dual strap), first aid kit, and any additional equipment required by company policy.