Layman’s Terms:
StoneBreak: Commonly called a Chip, is a sub-surfaced break on the outer layer of windshield glass, typically coin size and containing small radiating or extending cracks. Stone breaks are commonly referred to as star breaks, bullseyes, combination breaks, partial bullseyes or radiating cracks.
Crack: A surfaced single line separation in the outer layer of glass. Impact point: The location on the outside layer of glass which was struck, usually by a stone. Typically, a small piece of glass is missing. The impact point is the location for the chemical’s passage into the break. It is the size of this area of missing or pulverized glass that generally determines the visibility of the resulting repair.
Bullseye of a Stone-Break: The dark circle under the impact point (as seen before repair). Typically any small radiating cracks will converge into the bullseye. This is an open air space. The darkness is caused by light refraction in this open area.
Refraction: The bending of light rays in passing from one medium to another; the mirroring (shiny) image seen along the profile of a crack. Refraction should be significantly reduced or eliminated when the completed repair is viewed from its profile.
Head-on Angle: The view of the crack which is perpendicular to the profile of the crack. The head-on angle is a ”seam” and is always visible at the conclusion of a repair. This angle is not used by the technicians when repairing damage and is not a valid angle from which to determine the quality of a repair for inspection purposes.
Profile of crack: The angle which allows view of the entire thickness of the crack, from the outer surface of the glass to the lamination. The profile of the crack appears as light refraction and is the angle a technician observes when performing a repair. This is also the angle from which the repair MUST be inspected to accurately evaluate the quality of the repair.
Cosmetic Blemish: Small voids or air bubbles in the interior of any repair which appears as light refraction or dark spots. This specifically excludes the impact point.
Tip of Crack: The ends of the small cracks (“legs”) radiating from a stone break. After repair, should be invisible when viewed from the profile.
Deterioration: A tensile or adhesion failure of the resin which appears as an area not repaired or exhibiting refraction.
How to Inspect the Break
- Place the vehicle in the shade and go on the inside of the vehicle. Unfilled portions will appear black in color and will refract sunlight.
- Move around the break to check each leg/crack from its profile. Each leg of a star break can have a different profile and head-on angle. Each should be filled from the profile all the way to the tip. If the tip is not filled it can still crack.
- There should not be any black voids or refraction from the tip of the cracks or perimeter of the break. These defects can still spread or crack out. Small voids in the interior will not crack out and are considered cosmetic blemishes. A good repair will have no cosmetic blemishes.
- To confirm if a leg or crack is not filled, from the outside of the windshield carefully apply light pressure to the leg with your fingertip, a small screwdriver or an awl. If it refracts, turns black or moves, it is not filled and can still crack out.
