Car Windshields – Glossary

If you want to be sure that the repair or replacement of your car windshield is done properly, you will come across some terms that you are not familiar with. This glossary is designed to help you, defining the words in a way most helpful to someone new to car windshield repair/replacement.

A Pillar: The part of the car body on the sides of the windshield, that helps support the roof.

After Market: See Aftermarket.

Aftermarket: A term that refers to any car parts that were not made by the original manufacturer of the part.These may or may not meet the exact specifications of the manufacturer (in the case of windshields, the exact specs are often not available to the creators of aftermarket parts). See also OEM. To learn more, see Windshield Replacement: OEM or Aftermarket – or something else?

Anneal: A process of heating glass and then slowly cooling it, which helps relieve internal stress, making the lass less likely to break. Tempered glass is creating using annealing. See also Tempered Glass.

ARG: See Auto Replacement Glass.

Auto Replacement Glass: Abbreviated ARG. This is the industry term for aftermarket glass.

B Pillar: The part of the car body that supports the roof, that appears behind the A Piller. In most cars, this is the between the front and rear doors.

Bull’s Eye: Damage to glass caused by a rock (or other object) that is circular, typically with a cone in the outer layer of the glass.

C Pillar: This term normally refers to the part of the car body on the sides of the rear windshield, which help support the roof of the car. However, some vehicles have more than 3 pillars on each side, in which case this would refer to the third set.

Chip: Damage to glass caused by a rock (or other object) that causes a small piece of glass to come off the windshield. Read more about Windshield Chip Repair.

Combination Break: When there are multiple types of breaks in a windshield, such as a chip with cracks coming off of it.

Comprehensive: The type of insurance that covers most windshield damage in the United States, such as rocks being thrown up from the street.

Cure: The process where an adhesive dries and becomes as strong as it is supposed to be. See also Safe Drive Away Time.

Cure Time: See Safe Drive Away Time.

Deductible: The amount of money that you have to pay when insurance covers part, but not all, of the cost of a repair or replacement. For example, if you have a $250 deductible, and the cost to replace a windshield is $400, you would pay $250 and the insurance company would pay $150. Note that many insurance companies will waive the deductible if you repair a windshield rather than replace it (so the insurance company would pay the entire cost); if you have that option, and your windshield has never been replaced before, you should take it. Read more about Insurance Coverage and Deductibles for Windshields.

Department of Transportation: See DOT.

DOT: Short for Department of Transportation. This is the U.S. Government agency that handles transportation of all types. See our DOT Number Database. See also NHTSA.

Drive Away Time: See Safe Drive Away Time.

Edge Crack: A crack that starts within 2″ (5cm) of the edge of the windshield, or reaches the edge of the windshield. It normally forms immediately, and starts at 10-12″ (25-30cm) long.

Estimate: The sheet of paper that the repair shop or insurance company gives you that shows the estimated cost of repair. This should be given to you before the work is done. In many states, if non-OEM parts are used, the estimate must state this.

Fast Cure Urethane: An adhesive that can be used on windshields that cures quickly, allowing the car to be driven safely sooner. One brand has a safe drive away time of 4 hours if a passenger side airbag is present (45 minutes without one), under ideal conditions. See also Safe Drive Away Time.

Federal Motor Vehicle Safety Standards: See FMVSS.

Floater Crack: A crack that starts in the middle of the windshield (anywhere that is not within about 2″ (5cm) of the edge of the windshield).

FMVSS: Short for Federal Motor Vehicle Safety Standards. These are laws in the United States that cover vehicle safety, including windshields. See also FMVSS 205, FMVSS 212.

FMVSS 205: This is the law in the United States that covers the material that needs to be used for windshields, and requires them to have a marking. See also FMVSS.

FMVSS 212: This is the law in the United States that covers the mounting of windshields. See also FMVSS.

Frit: This is the painted black band around the perimeter of the windshield. The adhesive is underneath this band, so the band is able to help protect the adhesive from damage from the sun.

Glazing: Another term for glass. Can also refer to installing glass in a frame.

Half Moon: Damage to glass caused by a rock (or other object) that is similar to a bull’s eye crack, but not completely circular. Also called Partial Bulls-Eye.

Hardened: Glass that undergoes a process to make it more resistant to breaking that regular glass. See also Tempered Glass.

Impact Point: The location on the windshield where an object hit it that caused damage. Usually a small piece of glass chips off in this location.

Laminated Glass: This is actually two (or more) pieces of glass that are held together with a piece of plastic. If the glass breaks, it usually sticks to the plastic, making it less likely to injure people. The plastic can also help prevent occupants of the vehicle from being thrown out of the car.

Legs: A term for short cracks that extend from a pit.

Light Transmittance: The amount of light that passes through glass. For most car windows, this is required to be 70% or more.

Like Kind and Quality: A term used in many state laws to determine the type of replacement part that is acceptable for an insurance company to use. This means that if a part is not a new OEM part, it must be of the same quality. However, not all states use this term.

Lite: Regarding a windshield, this refers to a single layer of glass (as opposed to the whole windshield, which consists of two pieces of glass separated by a layer of plastic).

Long Crack: A crack that is over about 6″ (15cm) long, which many windshield repair methods are unable to fix.

National Glass Association: See NGA.

National Highway Traffic Safety Administration: See NHTSA.

NGA: National Glass Association. It is an association of companies involved in glass (automotive and otherwise).

NHTSA: Short for National Highway Traffic Safety Administration. This is a subsidiary of the U.S. Department of Transportation, that is responsible for the safety of cars. Among other things, they are responsible for the FMVSS series of laws that cover the safety of vehicles, including windshields.

Nitrile Gloves: Special gloves that are able to protect against solvents, urethanes, acids and resins. Installers of car windshields normally wear this type of glove.

OEM: Short for Original Equipment Manufacturer. This is a car part that either was made by the manufacturer of the car, or was ordered by the manufacturer of the car. Note that insurance companies in some U.S. states are allowed to use used parts, which should of course not be confused with new OEM parts. See also Aftermarket.

Original Equipment Manufacturer: See OEM.

Partial Bulls-Eye: See Half Moon.

Pinchweld: The part of the frame of the car that the windshield attaches to.

Pit: The area where glass is missing, after a rock or other item impacts the car.

Plastic Interlayer: The term for the piece of plastic that is between the inner and outer layers of glass on a windshield.

Polyvinyl Butyrate: See PVB.

PVB: Short for Polyvinyl Butyrate. This is the material that is normally used in the middle of two pieces of glass to form a windshield (or other laminated glass). It is a type of plastic. See also Laminated Glass.

Quarter Glass: A term used for triangular passenger or driver windows in a car, that typically cannot be opened, that are usually adjacent to the rectangular part of the window that can be opened.

Resin: A clear material that is used to fill in cracks and breaks in a windshield.

Safe Drive Away Time: The amount of time that you need to wait after a windshield is replaced before it can safely be driven. This time depends on the adhesive used, and other factors such as humidity. You may also be given two times; one where it is safe to drive the car (meaning that the adhesive is strong enough that the windshield won’t come off while driving), and another when it is safe to be in an accident (meaning that the windshield won’t come off as the result of the adhesive not having full strength yet). It is best, of course, not to drive the car until the adhesive has fully cured. See also Cure.

Safety Glass: Glass that is manufactured in a way to make it safer than normal glass. This usually involves either making the glass harder (making it more difficult to break, and when broken, the pieces are less sharp), or by laminating it. See also Laminated Glass, Tempered Glass.

Salvage Part: A used part that is obtained from a vehicle that is no longer functional (such as one that has been in an accident, flood, or otherwise would cost too much to fix). In many states, it is legal for insurance companies to use used parts.

Shaded Glass: Glass where only part of it is tinted. For example, the top of most windshields is tinted to help improve visibility.

Short Crack: This term typically refers to a crack that is short enough to be repaired by the more common windshield repair methods, which is about 6 inches (15cm) or less.

Star Break: Multiple small cracks coming out from the point where a rock or other item hit the windshield.

Stone Break: A small chip that occurs when a stone (or other hard item) hits the windshield. It can then become a large crack over time.

Stress CrackA crack that occurs without anything hitting the windshield, typically due to a large variation in the temperature (such as when the car is sitting in the sun, and then you start it and use the air conditioning). It almost always starts at the edge of the windshield. Stress cracks will normally be a straight (or slightly bending) line, and will not have any sign of impact. A “pen test” is often used to determine if there is a stress crack — a ballpoint pen is run along the crack, and if it dips anywhere, it is not a stress crack. That is because with a stress crack, no glass actually comes off the windshield.

Tempered Glass: A type of glass that is stronger than normal, and designed to shatter into small pieces (rather than large, sharp pieces) if broken. Tempered glass is made by heating it and then quickly cooling it.

Tinted Glass: Glass that blocks a noticeable amount of light. This reduces glare, and helps absorb heat. However, federal U.S. and many local laws require a certain amount of visibility. See also Light Transmittance.

Urethane: An adhesive material that is used to bond a windshield to the car.

Windshield: The glass that is used on the front of a car. It is made of laminated glass, and helps support the weight of the car in the event of an accident.

Wiper Sweep: The area of the windshield that windshield wipers clean.