In the wake of school shootings, public bombings, and bizarre street attacks here and abroad, it’s easy to become obsessed with stopping a specific threat scenario. Good security doesn’t address the specifics of any single event, but instead holistically increases safety and security.
Despite the name, “bullet proof glass” is not just for stopping bullets. An appropriately designed and installed bullet resistant window system is disaster-neutral, equally prepared to protect people from armed malcontents, extreme weather, industrial disasters, and other unforeseen cataclysms.
Broad security from bullet resistant windows
Monolithic acrylic is commonly used for lower-level bullet proof windows. This material is extremely hard (if somewhat brittle). In thick layers (over 1.25 inches) it will deflect most pistol-caliber bullets–even under sustained fire. Nonetheless, the pressure wave of a bomb blast or full-on impact of hurricane-flung debris will compromise these windows.
But bullet resistant windows built around polycarbonate thermoplastic (often sold under the trade name “Lexan”) have much broader applications. Polycarbonate is more resilient than any other glazing material. By flexing upon impact, polycarbonate can absorb tremendous impacts and pressure waves without cracking or spalling. Without polycarbonate layers, it’s currently impossible to make bullet resistant windows capable of stopping rounds from high powered rifles and submachine guns.
Beyond the standard bullet resistant window
But polycarbonate is also a soft material. While this has certain advantages–for example, polycarbonate usually “swallows up” bullets, rather than sending them ricocheting at high speed–this lack of rigidity can make it tricky to work with and maintain. In order to take full advantage of polycarbonates flexible resilience, it is laminated in layers with other materials, such as acrylic or tempered glass. This is the key to creating ultra-resilient glass-clad polycarbonate. These “bullet proof” windows go beyond just stopping bullets. “Forced entry-rated” polycarbonate windows will also foil smash-and-grab burglars and angry mobs, deflect bomb blasts, and even protect against earthquake damage and tornado-tossed bricks. Specially formulated and layered polycarbonate ballistic windows can possess even more exotic properties, such as “one-way” ballistic characteristics and even fire resistance.
On a weekly basis we see lives and property lost not just to bombs and bullets, but also to raging wildfires, super-storms, and civil unrest abroad. Good security doesn’t mean reacting to the last terrible event in the news and preparing to stop that specific threat, but instead training staff and reinforcing facilities so that they can stand up to any disaster, natural or man-made.