Understanding Your Damage
Bullseye, Star Break, Combination Break, and Crack: Windshield Damage Types Explained
When a rock or piece of road debris strikes your windshield, the resulting damage takes a specific shape determined by the speed of impact, the size and shape of the object, and the angle at which it hit. These shapes have names, and those names matter. Different break types behave differently under stress, accept resin differently during repair, and produce different visual outcomes after service. Understanding what you are looking at helps you know what to expect from the repair process and what questions to ask your technician.
How Windshield Glass Breaks: A Brief Foundation
A modern windshield is not a single piece of glass. It is a laminated assembly: two layers of annealed glass bonded to a plastic interlayer called polyvinyl butyral, or PVB. When an object strikes the outer glass layer with enough force to break it, the energy radiates outward from the impact point in patterns determined by the physics of the strike. The inner glass layer and the PVB absorb the remaining energy, which is why laminated windshields do not shatter on impact the way a side window does.
The break pattern left in the outer glass is what technicians classify and assess. Most chips are confined to the outer layer. When the inner layer is involved, the repair options narrow significantly.
Bullseye
A bullseye is the most straightforward and most successfully repaired type of windshield damage. It results from a direct, roughly perpendicular impact by a rounded object, typically a stone or gravel. The impact creates a cone-shaped void in the outer glass that radiates evenly from a central impact point, producing a circular shape when viewed from the front. The name comes from the resemblance to the center ring of a target.
Bullseyes repair well for several reasons. The circular geometry creates a self-contained void with no radiating cracks to complicate resin flow. The resin fills the cone cleanly, bonds to the surrounding glass, and cures with minimal visual artifact. A well-executed bullseye repair on a chip smaller than one inch is often difficult to notice in normal lighting conditions.
Bullseyes can also occur in a partial form, sometimes called a half-moon or partial bullseye, where the cone is incomplete because the impact was slightly off-angle. These repair with similar reliability to full bullseyes.
Star Break
A star break occurs when an impact point sends cracks radiating outward in multiple directions, resembling the spokes of a wheel or the points of a star. The central impact point may or may not have a distinct cone void depending on how the object struck the glass.
Star breaks are generally repairable when the overall diameter of the damage, measured from the tip of one crack leg to the tip of the opposite leg, is under one inch. The resin is injected into the central void and wicks outward into the crack legs under pressure, sealing the entire break.
The repair outcome for a star break is typically less visually clean than a bullseye repair. The crack legs remain visible as fine lines even after successful resin injection, particularly in direct or raking light. This is not a failure of the repair; it is a characteristic of the break geometry. The structural integrity is fully restored even when the cosmetic result is not perfect.
Star breaks with many long crack legs, or with legs that approach the edge of the repairable zone, carry a higher risk of one or more legs continuing to grow after repair. A technician will assess this risk and may recommend replacement if the star pattern is aggressive.
Combination Break
A combination break is exactly what it sounds like: a break that combines features of multiple types. The most common form is a bullseye or partial bullseye with additional radiating cracks or secondary impact points nearby. High-speed impacts from sharp or irregular objects often produce combination breaks.
Repairability for combination breaks depends on the total diameter of the damage area and whether any of the radiating cracks approach the edge of the glass or the driver's sightline. Within size limits, combination breaks can be repaired, but the visual outcome is more variable than with simpler break types. The more complex the break pattern, the more likely that some visual trace remains after repair.
When a combination break involves multiple closely spaced impact points, the intervening glass between them can become structurally weak. A technician will assess whether the glass between the damage sites can hold effectively after repair or whether the damage has compromised too much surface area.
Floater Crack
A floater crack is a crack that originates in the interior of the windshield, away from any edge. It may or may not have a visible impact point. Floater cracks are often the result of a small, fast impact (a sand grain or tiny gravel chip at highway speed) that creates a crack without leaving a noticeable chip.
Short floater cracks, generally under three inches, may be repairable depending on their location. Longer ones typically require replacement. Because floater cracks often lack a distinct void to inject resin into, the repair process is more technique-dependent than bullseye or star break repairs, and visual outcomes are less predictable.
Edge Crack
An edge crack originates at or within two inches of the windshield border. It may result from an impact near the edge, from stress caused by improper installation, or from temperature cycling that concentrates stress where the glass meets the frame.
Edge cracks are almost universally unrepairable and require windshield replacement. The reason is structural: the edge of the windshield is where the glass is bonded to the vehicle frame. A crack at this location is under constant stress from vehicle flex, vibration, and thermal expansion and contraction. Even a successfully injected repair in this zone will typically continue to propagate because the underlying stress that caused the crack has not been addressed. More importantly, edge cracks compromise the structural contribution the windshield makes to the vehicle's roof crush resistance and airbag deployment support.
Stress Crack
A stress crack is a crack that appears without any visible impact point. Drivers often discover these overnight, after a cold night or a hot afternoon, and are puzzled about the cause. Stress cracks result from temperature differentials across the glass surface. The most common scenario is running a hot defroster on a very cold windshield: the center of the glass expands while the edges remain cold, and the tension creates a crack.
Stress cracks almost always start at the edge of the windshield, where thermal and structural stress concentrates. They often run straight across the glass for a significant distance. Because they originate at the edge and extend well into the glass, stress cracks virtually always require replacement. Repair injection cannot address the root cause, and the crack will typically continue to grow.
Stress cracks are more likely to occur in windshields that already have some existing damage or micro-fractures. A chip near the edge acts as a stress concentration point, and a cold morning may be enough to turn it into a full crack. This is one of the reasons addressing even minor edge chips quickly matters.
Pit or Surface Chip
A pit is a very shallow chip that has not fully penetrated the outer glass layer. Pits are often caused by fine debris like sand or small gravel at highway speed. They appear as tiny craters or pockmarks in the glass surface.
Pits below a certain depth may not be injectable: if the void is too shallow to accept the resin delivery system, the repair cannot be completed. However, many surface pits are repairable and, because they are shallow, respond well to resin with clean visual results. A technician will probe the pit to determine whether injection is feasible.
Over time, accumulated pitting across the windshield surface creates a haze that scatters light, particularly at night and when driving toward a low sun or oncoming headlights. Individual pits may be too small to repair, but the cumulative effect can reach a point where replacement is justified on visibility grounds alone.
Long Crack
A long crack is any linear crack longer than three to six inches, regardless of origin. Long cracks require replacement in virtually all cases. The resin injection process can seal a crack structurally, but as crack length increases, the forces that caused the crack to propagate remain, and the likelihood of continued growth after repair rises proportionally. Beyond six inches, resin cannot reliably restore the structural integrity the windshield requires.
Why Break Type Affects Your Repair Outcome
Understanding break types matters because repair is not a uniform process. Each break geometry interacts with the resin and delivery system differently. A technician who can accurately classify your damage can predict the likely structural and cosmetic outcome of a repair before beginning work. That transparency lets you make an informed decision rather than discovering the result after the fact.
At Keystone Auto Glass, we assess break type as part of every damage evaluation. If a repair is viable, we explain what outcome to expect. If it is not, we explain why and walk you through replacement options.