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On a weekly basis, we see lives and property lost, not just to bombs and bullets, but also to raging wildfires, super-storms, and civil unrest. Good security doesn’t mean reacting to the last terrible event in the news and preparing to stop that specific threat. Total security focuses on training staff and reinforcing facilities so that they can stand up to any disaster, natural or man-made.
The right ballistic glass is an important element of such a security strategy. Despite the name “bulletproof glass,” ballistic windows aren’t just for stopping bullets – and they’re not always made of actual glass. The technology behind ballistic polycarbonate has come a long way over the years and there are more options available than even 5 or 10 years ago.
How is Ballistic Polycarbonate Different from Acrylic Safety Glass?
The most modern ballistic glass includes at least one of the following thermoplastics:
- Acrylic (often sold as “plexiglass” or “perspex”) or
- Polycarbonate (familiar to many under the trade names Lexan, Cyrolon, or Merlon)
Both these materials are lighter than glass, weighing roughly half as much at equivalent dimensions. Both are forms of bullet proof plastic that are stronger than actual glass. Acrylic offers about 17 times greater impact resistance compared to glass. Polycarbonate is even better, measuring an astounding 250 times more resilient than glass.
In most cases, deciding between acrylic and polycarbonate options comes down to what features matter the most in a situation, and how the material will be applied.
Polycarbonate is more resilient to impacts but it is softer and thus scratches more easily. Nonetheless, softness has its advantages. In this case, that softness lends it resilience. By flexing upon impact, polycarbonate can absorb tremendous impacts and pressure waves without cracking or spalling. When shot, polycarbonate usually “swallows up” bullets, rather than sending them ricocheting at high speed.
Meanwhile, acrylic plexiglass is harder—and less likely to scratch. Manufacturers can even buff it out to a high-gloss finish, like glass. And, similar to glass, that hardness makes it more likely to crack or chip. If it repels a bullet, that bullet ricochets unpredictably, and can injure bystanders on the “threat side” of a barrier.
In equal thicknesses, acrylic is more transparent than polycarbonate. That said, given polycarbonate’s greater strength, a thinner piece may work just as well in a given application. That will at least somewhat reduce the impact of its poor light transfer characteristics.
As you shift your focus specifically to ballistically rated materials, the “Acrylic vs. Polycarbonate” debate becomes much more one-sided. You’ll generally find that bullet-resistant windows built around polycarbonate thermoplastic have much broader applications in building safety and security.
Lamination Unlocks the Benefits of Ballistic Polycarbonate
Polycarbonate is more resilient than any other glazing material because it can flex. But that lack of rigidity makes it tricky to work with and maintain. To take full advantage of polycarbonate’s flexible resilience, manufacturers with other materials, such as acrylic or tempered glass.
This combination of laminated materials is the key to creating ultra-resilient glass-clad polycarbonate windows that go beyond just stopping bullets.
Because they laminate bulletproof plexiglass windows in layers, manufacturers have the option of including other materials to improve performance, aesthetics, or both. For example, they can be made to add window frosting or tints, or be reinforced with wire mesh.
Owing to its inherent resilience, even a thin sheet of polycarbonate has built-in “forced entry” qualities. This can deter smash-and-grab burglars and angry mobs, deflect bomb blasts, and even protect against earthquake damage and tornado-tossed bricks. Specially formulated and layered polycarbonate ballistic windows can possess even more exotic properties, such as “one-way” ballistic characteristics and fire resistance.
The point is- there are more options than you might realize in working with ballistic polycarbonate.
The Biggest Benefit of Ballistic Polycarbonate: Stopping Bigger Bullets
When considering the best options, you might start by considering the stopping power your bullet-resistant glass or glass-like material needs.
Take a moment. Consider the powerful and accurate .223 cartridge. This is the consumer version of the military’s 5.56 ammunition, used in M16 assault rifles (which are themselves based on the Colt AR-15 semi-automatic tactical rifle—the basis for the popular “AR” platform for modern sporting rifles).
The .223 has a fairly small bullet, with similar dimensions to the .22 long rifle. But the .223 bullet is a little heavier, much more aerodynamic, and powered by much more gunpowder. The result is one of the fastest bullets available to the public—a projectile that strikes roughly ten times harder than a .22, despite being only about 30% heavier.
The combination of a small, aerodynamic projectile moving incredibly fast makes the .223 especially hard to stop with standard bulletproof windows, so understanding when and where to add extra reinforcement is crucial to your overall security plan.
How Polycarbonate Stops High-Powered Ammunition
As we explained above, defending a high-powered rifle calls for an entirely different approach than defense against pistols and handguns.
Not only must the ballistic glass be thicker–at least 1.625-inches thick, if not 1.75–it also needs to be of an entirely different composition. You need to combine the hardness and rigidity of something like acrylic or glass with the inherent impact resistance of polycarbonate. Without polycarbonate layers, it’s nearly impossible (and certainly not cost-effective) to make bullet-resistant windows capable of stopping rounds from high-powered rifles and submachine guns.
The only bullet-resistant glass that’s going to stop a .223, for example, is glass-clad polycarbonate. This laminated ballistic transparency is made by stacking layers of tempered glass and polycarbonate interleaved with thin layers of urethane epoxy.
When a .223 strikes a window made of glass-clad polycarbonate, the outer surface of tempered glass forces the projectile to partially pancake, spoiling its aerodynamic design. That tempered glass then shatters, and the inner layers of epoxy and polycarbonate flex like a backstop. Because this material is softer and denser than bullet-resistant glass or acrylic, it often swallows the bullet up and holds it. While an acrylic-based bullet-resistant window is unlikely to stop even a single .223, a rated UL-Level 7 system using glass-clad polycarbonate ballistic glass will easily catch a tight burst of these bullets.
Three Options for Ballistic Polycarbonate, and How They Compare to Ballistic Insulated Glass Windows
In general, polycarbonate sheets find their way into ballistic windows in one of three ways:
All Polycarbonate Windows (LP 750, LP 1000, LP 1250)
All-polycarbonate bulletproof plexiglass windows are made of multiple sheets of polycarbonate laminated together. They usually have a pair of thicker standard polycarbonate sheets in the middle—to give the window strength—with thinner mar-proof layers of polycarbonate on the outermost surface to minimize scratching and scuffing.
This material is very easy for experienced bulletproofing companies (like Total Security Solutions) to work with. With all-polycarbonate windows, your design can be very intricate. Ballistic barrier system manufacturers can cut and fabricate these windows to blend in with any building aesthetic. You’ll have many options for talk-thrus, slots, fasteners, and so on. These windows can be framed, or sport exposed polished edges.
All-polycarbonate windows are thinner and lighter than a ballistic acrylic window with the same protection levels. Most suppliers can furnish polycarbonate windows in UL Levels 1 through 3. (These provide protection from a wide range of easily concealed handguns.) All-polycarbonate ballistic windows also carry a UL-tested forced-entry rating. In other words, third-party labs have tested the windows and confirm that they will completely withstand breaching, even after an hour or more of constant battering with sledgehammers and other tools.
But there is a trade-off: an all-polycarbonate bulletproof window has relatively poor light transmission (around 70%, compared to acrylics +90%), despite being one-third thinner and lighter than its acrylic counterpart.
Acrylic/Polycarbonate Windows (LP 1250 BR)
These bullet-resistant polycarbonate windows combine the aesthetic advantages of acrylic (glossy finish, extremely clear, easily fabricated into complex systems with polished exposed edges and intricate cuts) with the strength of polycarbonate. Usually, they have a 1″ acrylic core laminated to a set of 1/8th inch mar-resistant polycarbonate outer layers. Adding those polycarbonate caps doesn’t just strengthen the acrylic (bringing it up to Level 3 stopping power)—it also adds some measure of forced-entry and blast resistance to the material (although it does not carry an official UL rating for forced entry at this time).
Glass-Clad Polycarbonate Windows (GCP)
Glass-clad polycarbonate ballistic windows are made of laminated layers of tempered glass and polycarbonate. These windows are available in Levels 1 through 8 (with those higher levels able to stop multiple bursts from high-powered assault weapons and tactical rifles). There are many different options when layering glass and polycarbonate in a GCP window, depending on the application. These can tune the windows aesthetically (e.g., adding tint, mirroring, frosting, etc.) or increase energy efficiency (with “low E” interlayers). GCP windows may have polycarbonate or glass outer layers, depending on the security and design needs of the building owner.
Because of the many layers of glass, polycarbonate, and urethane, these are extremely difficult to cut, form, and fabricate. They perform best as solid frame-mounted sheets, often for exterior windows.
Insulated Glass Windows
Technology is always evolving, and improvements have been made in the use of (actual) glass in ballistic usage. For example, our Defender glass offers customizable options that can meet many of the needs that were previously better met by bulletproof plastics, including both acrylic and polycarbonate options.
Whichever type of material you end up choosing for your windows, the framing is just as important to ensure overall safety.
Appropriate Framing for Ballistic Polycarbonate Windows
A bullet-resistant window isn’t just a hunk of ballistic polycarbonate. To keep people safe, these windows need to be mounted in true ballistic framings, not just plain steel. (The .223 round, for example, was designed to penetrate 14-gauge steel and will also penetrate the untested fiberglass “packed” frames some bulletproof companies use to hold down costs.)
Bulletproofing experts like Total Security Solutions CEO Jim Richards always advise that their high-level bullet-resistant windows be mounted in true Level 3 UL-rated bulletproof aluminum frames.
TSS offers a wide variety of ballistically rated window framing, including high-efficiency thermal break window framing systems, and consulting with one of our ballistic experts will help you ensure that you choose the right material for both your windows and frames.
Real-World Examples of Ballistic Polycarbonate Applications
How to Increase Airport Safety with Polycarbonate Ballistic Barriers
Every major public airport in the US was built prior to the September 11 attacks. As a result, most have been massively re-engineered to create new security bottlenecks and checkpoints. These, in turn, have themselves created new security concerns. First, if a would-be terrorist is caught at a bottleneck, they are likely to put up a fight, either firing bullets or causing TSA officers to shoot. Second, crowds at screening checkpoints are themselves attractive targets for violence. These threats necessitate renovation and innovation. For example, some airports have implemented bulletproof man traps around their metal and bomb-residue detectors, instantly quarantining anyone setting off an alert.
Historically, airports have used half-inch tempered glass partitions as barriers. These are clear–allowing for good sightlines–and can stop anyone from jumping a line or running off when challenged. But they offer no meaningful impact resistance. They won’t stop bullets or contain shrapnel and won’t provide a safe backstop.
Airport screening checkpoints should be designed to stop blasts and bullets while maintaining the bright aesthetics and good sightlines that travelers need. For airports, Jim favors walls of clear glass-clad polycarbonate, at least two inches thick, with true UL-rated bullet-resistant frames. These need not reach all the way to the high airport ceilings; six- or seven-foot-tall partitions will stop bullets, deter fleeing attackers, and focus a blast safely into the ceiling and away from travelers. Although it may be costly upfront, in contrast to the bulk of airport security, a ballistic glass installation is uncontroversial. It is unlikely to come with ongoing maintenance costs or create civil liberties and liability headaches.
How to Increase Security at Municipal and City Buildings
A decade ago, Jim Richards marveled at how often cost-cutting won out over safety in municipal facilities and city offices.
“I was always shocked,” he notes, “at the number of precincts in Detroit that didn’t have bullet-resistant glass. Most of Chicago didn’t have bullet-resistant glass. There were so many big cities in this country where the police precincts and municipal buildings, let alone airports and other public spaces, didn’t have what we would consider adequate protection.”
That has changed drastically over the intervening ten years. Today, Jim finds that most city offices are looking at Level 3 ballistic security. In doing so, they usually rely heavily on Level 3 acrylic-core polycarbonate windows (i.e., “LP 1250 BR.”)
A Level 3 piece of ballistic polycarbonate will stop at least three shots from a .44 Magnum. It’s not at all unusual for TSS’s Level 3 bulletproof windows and frames to stop more than a dozen shots.
(Their Level 3 ballistic steel doors regularly stop over 100 shots, including rounds from weapons well above their rating, such as tactical assault rifles.)
“LP 1250 BR is really good for municipalities,” Jim notes. “It offers all the stopping power you need, plus some forced entry protection. But more importantly, you retain all those aesthetic characteristics you get with acrylic. You can cut it, you can polish it, you can design those big ‘frameless’ systems that allow in so much light and give everyone great visibility, great communication. But at the same time, that’s a high-performance system. It’s going to keep people safe without getting in their way.”
Ballistic Polycarbonates in Corporate Offices
Similar to municipal buildings, corporate offices aim to maintain aesthetics while ensuring physical security. In corporate settings, however, there may be more options for how to best achieve this goal.
Government-owned buildings can ultimately be restricted in design, whereas corporate office buildings usually have more flexibility. It’s also worth noting that businesses looking to lease space from corporate office complexes are increasingly looking at overall building security when making those location-based decisions. That means that providing a secure space is in the best interest of any building owner and/or manager.
While most people are looking primarily at the overall look of a space, we want to make sure the design is still a priority. More so than others in the ballistic security field, Total Security Solutions is dedicated to aesthetics.
Building out safer spaces is becoming more of a priority, and we’re here to provide guidance on the best ways to do so.
So, which type of ballistic polycarbonate is best for you?
First, it’s important to note how the types work in different situations.
An appropriately designed and installed bullet-resistant window system is disaster-neutral. It is equally prepared to protect people from armed malcontents, extreme weather, industrial disasters, and other unforeseen cataclysms. Ballistic Polycarbonate can achieve all these goals and more, but which type is best for your project will depend on many different factors. Consulting with a ballistic expert can take the guesswork out of the process and ensure that you choose the right material for the job.
Reach out to us for support in customizing your next ballistic installation.