How Does Bulletproof Glass Work

How Does Bulletproof Glass Work

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how does bulletproof glass work

The need for bulletproof glass in the United States is at an all-time high. In 2022, the FBI categorized 50 shootings as active shooter incidents — with additional types of gun-based crime, such as armed robberies, also plaguing the country. With such a need for the technology, many property-owners have begun to wonder: how does bulletproof glass actually work? Is it even really “bulletproof?”

We’ve got all of your questions answered. Dive into this comprehensive guide for a brief history of bulletproof glass, an explanation on how it works, and other important explanations when purchasing a solution.

A Brief History of Bulletproof Glass

Like many great inventions, bulletproof glass was discovered by accident. In 1903, French painter, writer, and chemist Edouard Benedictus dropped a glass flask. Although the flask shattered upon impact, the glass shards remained together rather than spreading across the floor.

Upon examination, he discovered the flask was held together by a film, spurred by an alcohol solution of collodion. After a night of attempts to replicate the film, Benedictius created the first ever sheet of “safety glass” — sandwiching a film of cellulose nitrate between two sheets of untreated glass.

Through the years, Benedictus’s initial discovery has gone through continuous innovation and improvement, becoming widely accepted in diverse fields. From incorporation into warfare during both World Wars to its implementation on the PopeMobile, bulletproof glass is used across the world to protect those at risk from threats of active shooters.

Bulletproof or Bullet Resistant?

Don’t let the name fool you; no “bulletproof” glass solution is truly bulletproof. All bulletproof glass solutions are actually bullet resistant — designed to minimize the impact of bullets but not necessarily impenetrable. Bullets are incredibly high-impact, and can often be fired in rapid succession. In turn, even the strongest “bulletproof” solutions may break after enough rounds from a powerful enough firearm.

How Does Bulletproof Glass Work?

Bulletproof glass slows the impact of bullets by dispersing the kinetic energy of projectiles upon impact. When any surface is struck with a fast moving object, one of two things happens: the object shatters under the stress of force, or absorbs the impact as it spreads across the material. Glass, for example, has no means to absorb impact, thus shattering.

Bullet resistant glass solutions leverage several layers of protection to slow, then eventually stop, bullets upon impact. Take, for example, bulletproof glass made from laminated polycarbonate. With several layers of protection, bullets often get through multiple layers of protection, slowing to a point of stoppage before it fully penetrates the glass. Thanks to lamination, even penetrated layers stay together rather than falling into debris — both stopping bullets and protecting patrons from shatter.

history of bulletproof glass

What is Bullet Proof (Bullet Resistant) Glass Made Out Of?

There is no one thing that bullet resistant glass is made of; most types of “bulletproof glass” are composed of several materials, with multiple different variations of materials within the market as well. Some common & widely used types of bullet resistant glass include solid acrylic and laminated polycarbonate.

Solid Acrylic vs. Laminated Polycarbonate

Two of the most typical materials for bullet resistant glass are solid acrylic and laminated polycarbonate. Both are polymers — materials made from long lines of molecules chained together.

Polycarbonates refer to a group of thermoplastic polymers containing carbonate groups in their chemical structures. Installed as panels over existing glass or occasionally from scratch, polycarbonate solutions offer flexible installation for properties — alongside strength varying from UL 752 Level 1 through 8 per unique safety concerns. Polycarbonate powers several industry-leading bullet resistant glass solutions, including DefenseLite and BulletShield.

Acrylic, also known under brand names such as Plexiglas®, Perspex®, and Lucite®. Ranging in thickness from 1 ¼” to 1 ⅜”, acrylic comes in flexible sizes and is malleable to diverse installation needs. It resembles glass (with a transparency rate of 93%) while weighing 50% less than glass of equal thickness. Acrylic is less expensive than polycarbonate, and in turn is also less durable; even at maximum thickness, acrylic only meets UL 752 Level 1 requirements.

Ballistic Glass vs. Security Window Film

Often confused, ballistic glass and security window film are two different types of glass solutions. Although both provide impact resistance, ballistic glass and traditional security window film are made from different materials, both useful in separate situations. While security window film is excellent against most security threats, properties with specific concerns about bullet protection should opt for ballistic, bullet resistant glass.

Typically made from micro-layered, tear-resistant polyester film, security window film is designed to prevent break-ins, shatter protection, and smash & grab crime. The film absorbs the blunt impact of assailants, rather than shattering and allowing for easy access to a store. Meant to absorb blunt force, window film is not designed for the level of ballistic impact from a firearm. While window film may absorb some impact from bullets, UL-rated ballistic glass solutions are a better option for active shooter protection.

what is bullet proof glass made of

Common FAQs About Bulletproof Glass

With different materials and thicknesses to choose from, buyers of bulletproof glass have several key decisions to make before purchasing a solution for their property. Here are a few questions to consider, and our advice for purchasing.

How Thick Does Bulletproof Glass Need to Be?

The necessary thickness of bulletproof glass changes based on the unique security concerns of a residence or business; a store in a bustling city, for example, requires a different type of protection than an apartment building in the suburbs. Most bullet resistant glass solutions, such as BulletShield, are available in multiple thicknesses, customized based on the unique needs of a given property.

Additionally, thickness needs to change based on the type of material being used; because they’re different materials, one thickness of acrylic will have different protection than the same thickness in laminated polycarbonate. We recommend consulting a bulletproof glass installation professional to determine the exact thickness required for your security concerns.

How Does Angle of Impact Affect Bulletproof Glass?

Angle of impact greatly affects the damage done by a bullet; the smaller the angle, the more material a bullet has to pass through before reaching the other side. For example, a bullet approaching a vertical window at 90° has far less material to penetrate than one approaching at a 30° angle.

In turn, angled windows may need less thick glass to deliver the same level of protection from active shooters. To determine how angle of impact will affect the bullet resistance of your glass, contact a security window installation expert.

Install Bulletproof Glass With the Expert Team at Window Film Depot

With knowledge of how bulletproof glass actually works, property-owners can do a better job assessing the bullet resistance needs of their business or residence. However, even knowing the science, it’s impossible to maximize the effectiveness of bullet resistant glass without the help of an expert.

Here at Window Film Depot, we leverage a knowledgeable team of experts for seamless, comprehensive bullet resistant glass installation. Our network encompasses caring, compassionate window film professionals that will listen to your needs and figure out the ideal solution to protect your property from diverse threats, including active shooters. For more information, contact us today.