Ballistic glass is commonly assumed to fully protect occupants once a projectile is stopped. In reality, that perception can be flawed. Many ballistic incidents result in injuries even when the bullet is successfully intercepted, because the interior surface of the glass breaks apart under impact. Low-spall bulletproof glass was developed to reduce the release of hazardous glass fragments into occupied spaces. Instead of simply stopping a bullet, it manages impact energy so the interior side of the glass remains intact.
What Is Spall and Why Does It Occur
Spall results from the way glass responds to extreme ballistic stress. A high-velocity round striking ballistic glass causes the exterior layers to compress and slow the projectile while a shockwave travels through the laminate. As this energy reaches the interior surface, the protected side is subjected to intense tensile stress, a condition standard glass cannot accommodate. Without the ability to flex, the rear surface fractures outward, and even if the bullet is stopped within the glazing, sharp fragments can be expelled into the occupied space. These fragments, known as spall, act as secondary projectiles capable of causing serious lacerations, facial trauma, or permanent eye injuries.
Defining Low-Spall Bulletproof Glass
Low-spall bulletproof glass is a ballistic-rated glazing engineered to reduce or prevent glass fragments from being released on the protected side of the glass during a ballistic impact. Its purpose goes beyond stopping a bullet since it can control what happens to the glass after impact. Instead of allowing the interior surface to fracture and eject debris, low-spall bulletproof glass systems contain glass fragments and prevent them from entering the occupied space.
With occupant protection as the defining criterion, bullet-resistant glass systems are typically classified into three levels:
- Standard ballistic glass- stops the projectile but allows significant interior fragmentation, which can eject glass shards into the protected space.
- Low-spall ballistic glass- limits rear-surface debris to levels unlikely to cause injury, reducing the risk of secondary harm to occupants.
- No-spall ballistic glass- prevents interior fragmentation entirely, keeping the interior side of the glass assembly free of hazardous debris.
Together, these classifications reflect how well a bullet-resistant glass system protects occupants after a ballistic impact, not just whether it stops a projectile. Although all three levels may prevent penetration, only low-spall and no-spall systems actively manage interior fragmentation. Low-spall designs reduce the risk of secondary injuries that often occur with standard ballistic glass by controlling how the glass breaks and containing debris on the interior side of the assembly. This level of fragment control is especially important in environments where people are positioned close to the glazing.
The Anatomy of a Low-Spall Bulletproof Glass Barrier
Early ballistic glass systems relied on thick, all-glass laminates that used mass alone to slow and capture a projectile. While effective at stopping penetration, these assemblies were heavy and often allowed significant fragmentation on the interior side. Modern low-spall bulletproof glass systems take a more controlled approach. Most combine glass with polycarbonate or similar composite materials and include a dedicated spall shield bonded to the interior surface. This flexible layer acts as a containment barrier, absorbing impact energy and capturing fragments as the glass fractures. By allowing controlled deformation rather than brittle failure, the spall shield prevents debris from being expelled into the occupied space. The outcome is a lighter, more consistent barrier that protects occupants and meets stringent ballistic resistance requirements.
Key Benefits of Low-Spall Bulletproof Glass
Improved occupant safety
Low-spall bulletproof glass is designed to contain glass fragments on the interior side of the assembly, reducing the risk of secondary injuries such as lacerations and eye trauma.
Reduced risk of secondary projectiles
Effective control of interior fragmentation reduces the risk of dangerous glass fragments being projected into the occupied space after impact.
Maintained visibility and situational awareness
When the interior surface of low-spall bulletproof glass remains intact and visually clear, security personnel can continue to observe their surroundings and respond appropriately during an incident.
Lower weight and structural demands
Modern low-spall bulletproof glass achieves high levels of protection without excessive thickness or mass, reducing loads on frames and supporting structures.
Long-term durability
Integrated spall-control layers are engineered to retain optical clarity and adhesion over time, ensuring consistent performance throughout the service life of the glass.
Critical Applications Where Low-Spall Bulletproof Glass Is Required
Close-proximity installations
Any location where occupants stand within arm’s reach of the ballistic glass typically calls for a low-spall or no-spall solution. Typical examples include teller windows, transaction counters, reception desks, guard booths, and security checkpoints.
High-density public environments
Schools, hospitals, and government buildings present elevated risk because interior glass fragments can injure multiple people in crowded spaces.
Critical infrastructure and security posts
Guard shacks, control rooms, and similar facilities need low-spall performance to ensure personnel remain uninjured and capable of responding during an active security event.
Advanced Low-Spall Bulletproof Glass Solutions from Armortex
A ballistic barrier only fulfils its purpose if it protects the people behind it, not just stops a projectile at the perimeter. Low-spall bulletproof glass can control interior fragmentation and reduce the risk of secondary injuries after impact, shifting ballistic protection toward true life-safety performance. At Armortex, low-spall and no-spall capability is engineered into our solutions through careful material selection, precision manufacturing, and rigorous testing, ensuring protection that performs at the moment of impact, as well as throughout all the critical moments that follow. For more information about our low-spall bulletproof glass products, including our bulletproof windows, secure glazing systems, and integrated ballistic barriers, contact Armortex’s team of specialists.
