“Bullet proof” and “security” are so tightly intertwined for most of us that it’s often surprising to learn about modern facilities where security doesn’t hinge on ballistic glass. Prisons, for example–despite their reputation as modern-day fortresses–are almost devoid of ballistic glass. It simply doesn’t suit their setting.
BRITTLE, BUT STOPS BULLETS
Total Security Solutions vice president Jim Richards is an expert in ballistic systems design, and he points out that although it’s counter-intuitive, much ballistic glass is actually fairly brittle. This brittleness is vital to how the glass stops bullets: The extremely hard surface deforms the projectile upon impact, then cracks and chips–which saps the bullet of energy and deflects its forward momentum. The bullet, no longer streamlined or flying efficiently, grinds into the ballistic glass, chewing itself up in the process.
This is great for stopping bullets, but also means that these materials are relatively easy to scratch, and might be rendered foggy by a careless janitor (or sly inmate) “cleaning” the ballistic glass improperly.
LITTLE CALL FOR STOPPING BULLETS
Ballistic glass isn’t really what a prison needs. There are few guns behind bars, and all are tightly monitored. What is much more important than a ballistic barrier is having clear barriers–making it easy to monitor inmates–without having to worry about those barriers being damaged by either malice or carelessness.
As Jim explains, “Imagine you’re building a new prison; that’s a $20 million facility. There might be maybe $20,000 in new ballistic glazing and frames in the whole scope of the project, but you need lots and lots of durable windows.” To put that in perspective, a $20 million prison complex–which might comprise several buildings on dozens of acres of land, and ultimately hold thousands of inmates–only includes a gas-station’s worth of work for a ballistic glass expert.
DETENTION GLAZING vs. BALLISTIC GLASS
What prisons and jails really need is “detention glazing.” This is half-inch thick polycarbonate, very similar to the polycarbonate used in some ballistic glazing. Polycarbonate is perfect for prisons because, unlike other ballistic glass, polycarbonate flexes and rebounds when struck. Detention glazing won’t stop a bullet, but the springy polycarbonate will deflect a rock or chair or hammer almost indefinitely.
