What is Bulletproof Glass and How Does it Work?

Bulletproof glass is a durable alternative to glass for structures and vehicles that need an additional level of protection. By using strong, sturdy plastics, bulletproof glass stopping a frenzy of bullets dead in its tracks, it is not fully impenetrable. In fact, no bulletproof glass is guaranteed to protect against all projectiles. Instead, bulletproof glass is meant to absorb energy from bullets upon impact. This means that “bulletproof glass” is a misnomer, leading industry experts to refer to this form of glass as “bullet resistant glass.” Despite this, it is very common to use “bullet resistant glass” and “bulletproof glass” interchangeably. As a result, when we refer to “bullet resistant glass” in this post, we are truly referring to bullet resistant plastic.

Bullet resistant glass has become a staple of high security efforts. It has been trusted as a barrier for many different uses, from protecting the storefront of a jewelry store from improvised projectiles, to protecting military and private vehicles from bullets. Bullet resistant glass does this by dispersing the projectile’s kinetic energy upon impact. Bullets will almost always pierce at least the first layer of material, anything—or anyone—on the other side. To learn more about what bullet resistant glass is and how it works, keep reading.


What is Bulletproof Glass Made Of?

Bullet resistant glass (commonly known as bulletproof glass) can be composed of several different materials, all offering a different level of protection. These levels of protection range from Level 1, which can sustain three 9mm bullets, all the way to Level 10 which can protect against a 50 BMG bullet. While a few different kinds of resins may be used for bullet resistant glass, acrylic, and polycarbonate plastic are extremely popular choices. This is because both polycarbonate and acrylic are extremely structurally sound with a high level of optical clarity. Polycarbonate in particular has become very easy to procure with better technology in plastics manufacturing.

Acrylic bullet resistant glass is one form of bullet resistant glass designed for conventional use. This type of acrylic bullet resistant glass is a single 1.25 inch thick sheet of acrylic that provides basic Level 1 protection. This type of bullet resistant glass is more than appropriate for situations where projectiles are breaking glass windows and can provide protection from a few 9mm bullets as well.

Another commonly used form of bullet resistant glass is bullet resistant polycarbonate. This bullet resistant glass is made by layering polycarbonate with polyurethane layers in between. A sheet of polycarbonate-based bullet resistant glass can provide three levels of protection from few 9mm bullets as well.

Another commonly used form of bullet resistant glass is bullet resistant polycarbonate. This bullet resistant glass is made by layering polycarbonate with polyurethane layers in between. A sheet of polycarbonate-based bullet resistant glass can provide three levels of protection: Level 1, Level 2, and Level 3. Here are the specifications of these three levels:

Level 1: This variety is .75 inches thick. Like the acrylic variety of Level 1 glass, this form of bullet resistant glass can protect against three 9mm bullets, while being half of the thickness of its acrylic equivalent.

Level 2: Polycarbonate with this protection level is just over an inch thick. This bullet resistant glass is able to protect again three .357 Magnum rifle bullets, giving significant protection for its thickness and weight.

Level 3: This is often the strongest variety of bullet resistant polycarbonate offered. It is about 1.25 inches thick, and can protect against three shots from a .44 magnum, an extremely powerful revolver.

To achieve greater levels of protection, it is typically necessary to layer glass with polycarbonate plastic. This creates a very thick, heavy, and durable glass. However, as the glass becomes more thick and durable, its ability to transmit light decreases. The weight and light transmission are important to note for design and practical reason—for example, a vehicle being used to protect its passengers must meet local requirements for window tinting, and should be light enough to not impede the movement of the vehicle. For these reasons, it is very common to select bullet resistant glass that provides the most practical level of protection possible, instead of the maximum level of protection.

How Does Bulletproof Glass Work?

As previously mentioned, bulletproof resistant glass usually uses alternating layers of plastic to absorb the force of an impact. First, the bullet will typically pierce the first layer of material. However, the next layer of polycarbonate plastic will provide much more resistance, and the bullet’s energy will be dissipated upon impact. If there is still enough force being applied by the bullet, the bullet will pierce the next layer of material. This process continues until either a layer of plastic stops the bullet, or until the bullet emerges through the barrier—with far, far less energy propelling it forward. At this point, even if the bullet pierces the bullet resistant glass its velocity will be decreased significantly, protecting those on the other side.

This functionality is why “bulletproof” glass is a misnomer-bullet resistant is engineered to minimize the kinetic energy of these bullets, even if they pierce the plastic. Unfortunately, bullet resistant glass is only effective against a few bullets at a time. Eventually, the protective qualities will wear off. However, bullet resistant glass is certainly more effective than simple, unlaminated glass. It will be almost completely ineffective at reducing the momentum of the bullet, and shards of glass can burst forward, potentially causing injury. While laminating the glass will provide some resistance, proper bullet resistant glass should certainly utilize acrylic or polycarbonate plastic.

The History of Bulletproof Glass

The concept of bulletproof or bullet resistant glass was first patented 1909 French chemist Edouard Benedictus. This initial concept used celluloids, an early precursor to plastic. The celluloid would be placed between two sheets of glass. Over time, this idea has evolved into several different methods with varying effectiveness. Years ago, it was very common to use several layers of glass layered with polyvinyl butryal (PVB) only. Due to plastics becoming much more affordable, bullet resistant glass now commonly utilizes sheets of acrylic or polycarbonate sheets.

When circumstances call for a high level of security, acquiring and installing bullet resistant glass should be a high priority. For best result, it is important to use sheets of polycarbonate. If basic protection from projectiles and bullets from weapons like handguns is needed, polycarbonate bullet resistant sheets can provide a sufficient level of protection. For more information on how polycarbonate can be utilized for protection, contact us.