Ballistic threats unfold without warning and do not allow for recovery. When bulletproof glass is struck, it must perform immediately, even if it breaks. In high-risk facilities, glazing typically represents both the first defensive surface and the most vulnerable portion of the envelope. Stopping a bullet addresses only part of the threat. The greater concern is how the energy disperses as the glass and polymer layers fracture. Poorly managed failure can turn broken glass into high-velocity projectiles aimed toward the occupants behind the barrier. This is where modern bulletproof glass proves its value, not by remaining intact, but by controlling fracture, capturing fragments, and preventing high-velocity spall whether or not the glass itself fails.
What is bulletproof glass?
Bulletproof glass is a layered composite engineered to control a projectile’s kinetic energy in stages, using materials that respond differently under extreme stress. Brittle materials dissipate energy by breaking and elastic materials dissipate energy by stretching. Effective ballistic glazing combines both types of behavior into a single system, protecting occupants by managing energy transfer and maintaining barrier integrity.
On the strike side, sacrificial glass layers are designed to fail first. If a projectile impacts the surface, these layers fracture in a controlled pattern that deforms the bullet and spreads its kinetic energy across a wider area. This initial damage is intentional. Through breaking early, the outer glass reduces the projectile’s velocity and moderates the peak force transmitted deeper into the panel. As the fractured energy moves inward, the role of the laminate changes. Rather than continuing to break, the system begins to absorb and restrain. Polymer interlayers embedded within the glass stack take over the load-bearing function once cracking begins. Materials such as polyvinyl butyral (PVB) and urethane remain elastic under extreme loading, despite the surrounding glass having fractured. While cracks propagate through the glass plies, the interlayers stretch instead of tearing. That elasticity binds broken fragments together, preserves panel continuity, and prevents the formation of openings. Instead of shedding shards or allowing debris to eject inward, the glazing continues to behave as a single barrier, containing fragments and keeping the threat on the outside.
Understanding high-velocity spall
High-velocity spall refers to fragments of the ballistic glazing that eject from the protected side of the barrier during impact. It accounts for why glass can successfully stop a bullet yet still pose a serious danger to the people behind it. When a projectile strikes glazing, the impact generates a compressive shockwave that travels through the material. In conventional glass, the wave reflects off the interior surface and converts into tensile stress. Because glass performs poorly in tension, the safe-side surface can rupture, flaking, bursting, or shedding sharp fragments inward.
Once released, those fragments can reach hazardous velocities. The risk of injury from high-velocity spall escalates in environments where occupants stand close to the glazing, which is common in teller lines, security counters, pharmacy windows, and guard booths. Within such tight geometries, spall becomes a significant injury mechanism, capable of causing harm even if the projectile itself never penetrates the barrier. This dynamic is what makes penetration resistance an incomplete measure of protection. A glazing system may technically stop a round and still fail its real purpose by forming secondary projectiles made of glass. That outcome undermines the intent of ballistic protection in operational settings. The goal is not merely to block a bullet, but to prevent the barrier from becoming a source of injury to the people it is meant to protect.
Engineering the catch: how it works despite failure
True no-spall protection begins by designing the safe side of the glazing to behave differently to the strike side. Advanced bulletproof glass achieves this through incorporating a polycarbonate back layer within a glass-polymer laminate engineered for fragment capture. Unlike glass, polycarbonate does not shatter. It flexes under load, absorbs energy through deformation, and retains embedded debris rather than ejecting it inward.
Safe failure depends on how the ballistic glazing system responds once fracture begins. As the outer glass layers break, the glazing consumes the projectile’s kinetic energy instead of reflecting it back toward the protected space. Sacrificial plies disperse force, polymer interlayers stretch to keep fragments bonded, and the polycarbonate layer acts as a final catch. Even when the strike face is heavily damaged and appears whitened, crazed, or spiderwebbed, the safe side can remain intact as a continuous membrane that prevents spall.
Once fracture begins, ballistic performance becomes a managed sequence instead of a single pass-or-fail moment. Impact energy is first dispersed by the breaking strike layers, then absorbed and restrained as it travels through the laminate in the direction of the safe side. Industry standards for ballistic glazing reflect this layered behavior. UL 752 classifies glazing by threat level, but spall control is treated as a separate, safety-critical consideration. No-spall systems are engineered to satisfy both criteria by stopping the projectile and retaining fragments on the safe side.
Preventing hazardous fragment ejection depends on controlled deformation rather than rigidity. The ballistic glazing is engineered to break, stretch, and flex in a specific order while preserving barrier continuity. Should the outer glass layers be heavily damaged or pulverized, the interior layers can remain intact enough to contain fragments and protect the space behind the glass.
Delivering total protection with Armortex
Armortex designs ballistic glazing to address the full ballistic impact, from stopping the projectile to controlling fragment release and preserving safe-side performance. Our UL 752 rated glass solutions span Levels 1 – 8 and support applications ranging across retail, commercial, and government environments. For enhanced spall control, our Glass-Clad Polycarbonate systems pair hard strike layers with a resilient catch layer. Moreover, our blast-resistant doors manage overpressure and retain fragments in blast-exposed conditions. Consult our experts now to locate a bulletproof solution that fits your risk profile, architectural requirements, and budget.
