Bullet-Resistant Glass: How Does It Work?

Let me tell you something right off the bat, you’ve been fooled for many years when it comes to this topic.

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 don’t act under the impression that terrorists can’t touch you if you were to lock yourself in a “bulletproof” cubicle.  Bullet-resistant glass just delays the impact of the bullets, i.e., it will take more than one bullet to shatter it completely. Therefore, from this point forward, I will refer to it as ‘bullet-resistant’ glass.

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 this Miraculous Glass Made?

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

This material is basically made by inserting a layer of polycarbonate material between layers of ordinary glass. The process is commonly called lamination. 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.

normalvsbulletproofglass1

Normal glass vs. bullet-resistant glass

The Science Behind its Protective Ability?

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

When a bullet is fired at bullet-resistant glass, its outside layer is pierced, but the polycarbonate layer present inside absorbs the bullet’s energy and distributes its impact considerably. Thus, the bullet is unable to exit the final layer, i.e., break through the glass to strike a target.

Some companies have developed “one-way” bullet-resistant glass, which is designed to stop incoming bullets, while simultaneously allowing the person at the receiving end to shoot back.

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 the polymer layer easily before breaking the glass, only slowing the bullet slightly.

hdr_glass

How one-way glass works

When all said and done, 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.

Here is a video demonstrating how bullet-resistant glasses of various thickness work.

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

References:

  1. Wikipedia
  2. Bulletproof Glass – Explain That Stuff
  3. How Stuff Works
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About the Author:

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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