You’ve probably heard the term “bullet proof glass” before. If you design or construct buildings, you’ve maybe even considered purchasing bullet proof glass solutions to provide extra protection for those structures; however, there are some misconceptions about what exactly bullet proof glass is and how it works. In fact, the term itself can be a bit misleading. Here’s what you should know about bullet resistant glass and what type of protection it provides.
Why No Glass Is Actually Bullet Proof
The term “bullet proof” suggests that glass or other materials are completely impervious or unaffected by ballistic impact. In reality, there is no glass currently available on the market that does not show any signs of impact after being struck by a bullet. Even the strongest windows and doors on the market will break down eventually under a continual barrage of bullets.
A more accurate term for the type of bullet proof glass that’s currently available is bullet resistant.
Bullet resistant glass does provide protection against ballistic attacks, helping to safeguard people and property in public buildings, government facilities, financial institutions, commercial enterprises, and other structures.
Insulgard is a leading manufacturer of bullet resistant glass and other architectural security products. Our experts can help you understand the advantages of different kinds of materials so you can choose the Insulgard security products that are right for your project’s needs.
What Is Bullet Resistant Glass?
To learn how bullet resistant glass works, you should first understand a bit about the science behind impact. When a bullet strikes an object, that object either absorbs the blow by catching that moving force gradually to spread out the energy from the impact, or it cracks under the stress of that force.
Glass doesn’t have any give that would allow it to absorb an impact, so it falls into the latter category. This means that when a bullet strikes a normal pane of glass, the pane simply shatters and allows the bullet to pass through—providing no meaningful resistance at all—and, in fact, adding an additional hazard in the form of scattering glass shards.
Bullet resistant glass, on the other hand, is composed of multiple layers of glass laminated together, or the combination of glass and polycarbonate laminated together. Bonding inner layers make sure the layers hold together, even when there’s an impact that causes fracturing, like that from a bullet.
So the glass can still crack, but it doesn’t break apart fully. This means that the bullet cannot penetrate the surface as effectively.
This distinction saves lives, and is why architects, glazing contractors, and other construction professionals turn to bullet resistant glass and other architectural security products when they need to plan and build secure environments.
How Bullet Resistant Glass Works
Scientifically, bullet resistant glass that is made up of multiple layers is able to absorb the energy from a ballistic impact. The energy spreads out sideways through the different layers rather than shattering the entire pane upon impact.
The bullet can still technically get through some layers of the laminate, but the make up is designed so that all the energy is absorbed and the bullet is stopped from penetrating the glass.
Ballistic Ratings
There are also different types of ballistic impact ratings. So certain types of bullet resistant glass are made to absorb the amount of energy from specific bullets or firearms. This allows the material to work as effectively as possible at slowing down those ballistic rounds that are most likely to threaten the building or structure.
In the bullet resistant glass industry, the most widely respected measure of a material’s ability to withstand ballistic assaults is the UL 752 rating by Underwriters Laboratories.
This designation is divided into 8 levels of bullet resistance. The lowest levels provide protection against smaller handguns, while the highest levels protect against repeated shots from high-powered assault rifles. The variety of levels enable construction professionals to select the product that is best suited for a given structure or project.
Ballistic Testing
When you purchase bullet resistant glass from Insulgard, you can be sure that your products have been thoroughly tested to meet the rigorous UL 752 testing requirements. Key aspects of ballistic testing include:
- Ballistic firing: Testers fire specific calibers of bullets at the glass from a controlled distance, following standard velocities. The number of shots and their spacing are predetermined. Multiple impact points: The glass is tested at different points, including edges and center, to evaluate its overall resistance.
- Spall testing: The test determines whether fragments of glass shatter and spread, also known as spalling, a dangerous secondary effect of ballistic attacks.
- Pass/fail criteria: The glass passes if it prevents penetration of the round and any glass spall from coming to the interior/safe side of the specimen.
These tests help manufacturers rate bullet resistant glass into levels, allowing buyers to select the appropriate protection for their needs.
Types of Bullet Resistant Glass
There are several varieties of bullet resistant glass, each designed for different levels of protection, durability, and applications. The most common types include:
Acrylic Glazing
A strong, single-layer plastic designed to absorb and distribute the impact of lower-level ballistic threats (UL 752 Levels 1-3), preventing bullet penetration and interior spall.
Laminated Polycarbonate Glazing
These bullet resistant sheets provide a secure yet lightweight solution, making them ideal for interior use. This glazing is easy to work with and can be customized to a wide array of shapes and sizes.
Glass-Clad Polycarbonate Glazing
A hybrid of laminated glass and polycarbonate, offering enhanced scratch resistance and higher levels of UL protection. It is often used in high-security settings like government buildings and military installations.
All-Glass Laminate Glazing
The all-glass option provides exceptional optical clarity and easy maintenance, along with thermal and acoustic insulation. While suitable for both interior and exterior use, it excels in outdoor conditions due to its weather and UV resistance.
Wide Range of Applications for Bullet-Resistant Glass
Bullet-resistant glass enhances security across various industries by providing protection, visibility, and deterrence against threats.
Where It’s Used:
- Financial Institutions & Retail Stores – Protects employees and assets while maintaining clear visibility.
- Security Checkpoints & Government Buildings – Withstands ballistic assaults and forced entry attempts.
- Military Facilities – Establishes security in high-risk environments.
- Schools & Public Buildings – Reinforces doors, windows, and entry points to improve safety during active shooter incidents and emergencies.
Beyond protection, bullet-resistant glass also acts as a strong deterrent, signaling to potential criminals that they’ve chosen the wrong target.
What “Bullet Proof” Glass Is Right for Your Project?
Selecting the right bullet-resistant glass depends upon a number of factors, including:
- The threat level facing the structure
- The type and function of the business or organization
- Environmental factors such as rain and wind
- Non-ballistic threats such as severe weather events and forced entry
If you’re interested in learning more about bullet proof or bullet resistant glass products, contact us or request a quote today. Insulgard offers a wide array of security solutions, including bullet resistant windows, doors, frames and other ballistic protection systems. Our team of experts can help you find the custom solution that works best for your building project or business.
