Bullet-Resistant Glass: How Does It Work?

Bullet-resistant glass is made by inserting a layer of polycarbonate (a tough transparent plastic) material between layers of ordinary glass. When a bullet is shot at a sheet of bullet-resistant glass, it penetrates the outer layer of the glass, but the polycarbonate-glass material absorbs most of the bullet’s energy and significantly distributes its impact, keeping the target safe.

To begin with, there’s no such thing as bulletproof glass. What is commonly referred to as ‘bulletproof’ is actually just ‘bullet-resistant’.

No glass is impenetrable, so please don’t act under the impression that a gun-wielding madman can’t harm you if you were to lock yourself in a “bulletproof” cubicle.

What is bulletproof glass?

As mentioned above, in relation to glasses, a more accurate term is bullet-resistant glass.

To the naked eye, it looks just like an ordinary glass pane, but this is no ordinary sheet of glass. It can withstand the impact of several rounds of bullets, depending on the thickness of the glass and the caliber of the bullets.

Bullet-resistant glass delays the impact of bullets, that is, a bullet won’t penetrate it straightaway; it will take more than one bullet to shatter it completely.

A politician in West Africa was attacked in a bulletproof car with AR-15s and an 18 wheel semi and survived.

A politician in West Africa was attacked in a bulletproof car with AR-15s and an 18-wheel semi and survived.

How is bullet-resistant (bulletproof) glass made?

Bullet-resistant glass is made by inserting a layer of polycarbonate (a tough transparent plastic) material between layers of ordinary glass. This process is commonly called lamination, and it creates a glass-like material, but it’s much thicker than ordinary glass. The polycarbonate material imparts a general toughness and flexibility to the glass.

Some of the materials sandwiched between the glass include Armormax, Makroclear, Cyrolon, Lexan and Tuffak. Usually, bullet-resistant glass is 7 to 75 mm in thickness.

Normal glass vs. bullet-resistant glass

Normal glass vs. bullet-resistant glass

How does bulletproof glass work?

Obviously, bullets fired from a gun don’t just bounce off a surface (unless you’re the Terminator, of course).

When a bullet is shot at a sheet of bullet-resistant glass, it penetrates the outer layer of the glass, but the polycarbonate-glass material absorbs most of the bullet’s energy and significantly distributes its impact. Now, the bullet’s kinetic energy is ‘sapped’, so it’s not able to exit the final layer of the glass.

This means that the ‘target’, whom the glass shields, remains protected.

One-way bulletproof glass

Some companies have developed “one-way” bulletproof glass, which is designed to stop incoming bullets, while simultaneously allowing the person at the receiving end to shoot back. Although this is commonly known as one-way bulletproof glass, as mentioned earlier, it’s actually one-way ‘bullet-resistant’ glass.

This glass works by reinforcing a brittle glass layer, and again, utilizes a tough polymer layer. The brittle layer faces outwards and shatters if a bullet is fired at it, thus spreading the force of the bullet over a large area, which is then absorbed by the tough (polycarbonate) layer behind it.

 

A bullet fired from the other side, however, can puncture t

bullet proof glass

How one-way glass works

he polymer layer easily before breaking the glass, so it only slows the bullet slightly.

When was bulletproof glass invented?

Bulletproof glass was first invented by a French scientist named Édouard Bénédictus in 1909. Of course, back then, the bulletproof glass he developed was vastly different from what we have today. His idea for bulletproof glass was based on laminated safety glass, which is the same concept upon which modern bullet-resistant glasses are based.

The idea of the French inventor revolved around using a celluloid sandwiched between two sheets of glass.  The idea of using polyvinyl plastics to make bullet resistant glass was brought forth by Earl Fix of the Pittsburgh Plate Glass Company in 1936.

Bullet-resistant glass is a necessity in war-torn countries like Syria, Iraq and Afghanistan, as well as for government officials and prominent leaders all over the world.

Bullet-resistant glass really gets less credit than it deserves. It’s a very important innovation that has saved the lives of countless people, from the military to the very highest echelons of church and state.

References:

  1. Nap.Edu
  2. NIJ Journal
  3. MIT News
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Ishan is a Mechanical Engineer from Mumbai University, India and is obsessed with science, food and all things football. He is a self proclaimed cyclist, runner and a professional procrastinator.

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