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As Total Security Solutions CEO Jim Richards explains, “There are many different ballistic glass products out there, all of them are fit for different applications—and most people call all of them ‘bulletproof glass,‘ no matter what they are.” Specifically, there are five types of bulletproof glass commonly sold today. You see them everywhere: pharmacies, banks, shops, schools, government buildings, community centers, houses of worship, and so on.
The five most common types of bulletproof glass are:
- traditional laminated glass
- insulated ballistic glass
- glass-clad polycarbonate
1 Traditional Laminated Glass
Laminated glass is the original “bullet proof glass.” It’s crafted from layers of glass and resin, similar to a thick stack of modern car windshields. This old-fashioned glass is no longer very useful in most bullet resistant installations: It’s heavy, brittle, and cannot be readily cut, slotted, drilled, or otherwise smoothly incorporated into an integrated bullet resistant system. Experienced fabricators like TSS do have the equipment and know-how to build quality systems with laminated glass. But it still typically takes an additional 6 to 8 weeks to build such systems.
“These days,” Jim Richards explains, “this is an alternative product for people who aren’t facing a ballistic threat, but still need to keep people out and keep their window intact. It’s a more permanent and viable solution than aftermarket films, but it relies on a big thickness to build up to a ballistic security level. It also tends to have a distinct greenish tint. In most applications, there are just better solutions available.”
2 Insulated Ballistic Glass
Insulated ballistic glass is a whole new generation of bullet resistant security glazing. These are technically “secure IG (insulated glass) units,” and were first developed for schools and similar cost-conscious, non-traditional targets (like houses of worship and community centers), Secure IG units combine the best qualities of several different kinds of glazing. These are just 1-inch to 1.125-inch thick, but can carry both a forced-entry and UL Level 1 bullet-resistant rating. As a glass-based security glazing, it’s good for both interior and exterior applications, and easier to maintain. Because it’s an insulated glazing unit, it has excellent light transmission, a high r-value, and is even available in passive self-tinting varieties. These enhance occupant comfort and lower building cooling costs, but don’t carry the maintenance burden of a sensor-based or electronic window treatment.
“This is the only glass like this on the market,” Jim notes. “It’s not just bullet resistant, not just forced-entry rated, not just energy efficient. It’s all of these, a real ‘best of both worlds’ product. This is an upgrade and investment that makes everyone’s life better every day—not just during an extremely terrible event.”
By far, the most common type of “bulletproof glass” you’ll see is monolithic acrylic. This is a single piece of 1 1/4″ to 1 3/8″ solid plastic. Acrylic can be drilled, routed, cut, slotted—even formed into custom curved windows. Acrylic passes light almost perfectly. Its rough-cut edges can be flame-polished clear, making acrylic the go-to material for the attractive, unobtrusive installations favored in most public buildings.
Bullet resistant systems relying on monolithic acrylic can be fabricated to UL-rated Level 1 or 2 bullet resistance. A Level 1 system can stop three jacketed 9mm bullets, while a Level 2 system can stop three shots from a .357 Magnum. To beef up to Level 3 security—capable of withstanding at least three rounds from a .44 Magnum—Total Security Solutions sandwiches 1″ of acrylic bullet proof glass between two sheets of polycarbonate—making it into an LP (laminated polycarbonate) acrylic window. This keeps the excellent material qualities of the acrylic while adding some of the bullet-grabbing capacity of polycarbonate (described below).
While acrylic can be used for both interior and exterior windows, Jim tends to limit it to interior applications. “Acrylic—like all plastic-based transparencies—has issues with crazing and hazing and UV light. When you have an exterior window, you just really can’t control what chemicals it comes into contact with. And the sun eats everything over time. All that increases the chances of the glazing not looking great as it ages.”
Although they are both good for Level 1 through 3 bullet resistant barriers, polycarbonate and acrylic are very different beasts. Acrylic is hard, and polycarbonate comparatively soft. When used on its own in a bullet resistant system, polycarbonate is laminated in layers. Consequently, it has a noticeable tint, passing a bit less than 80 percent of available light. This can make for a gloomy interior.
But polycarbonate can offer Level 1 protection in just 0.75 inches of thickness, Level 2 at one inch, and Level 3 at 1.25 inches. In the past, it was popular for exterior windows because of its resistance to forced entry: a sheet of polycarbonate will take an hour of beating with a sledgehammer. While hard acrylic chips when hit by a bullet, sending the bullet (and acrylic spall) ricocheting, Jim points out that “polycarb looks beautiful when it stops a bullet: since it’s soft, it sucks the bullet in like a catcher’s mitt.”
That said, polycarbonate has its pitfalls. Like laminated glass, it’s challenging to fabricate into a smooth bullet resistant systems. And it has a noticeable tint. Like acrylic, it’s sensitive to UV and prone to crazing.
“We don’t make a lot of all-polycarbonate systems any more,” Jim explains. “There are just better solutions for facilities who are dealing with complex threats. This may be the material you want if you need just a straight forced-entry rating and like the darker tint. But if that’s not the case, you’ll probably be happier with a different material.”
5 Glass-Clad Polycarbonate
Glass-clad polycarbonate (GCP) is a high-tech spin on that old-school laminated bullet proof glass. For example, Level 3 glass-clad polycarbonate (capable of stopping three rounds from a .44 Magnum) is a 0.375-inch thick layer of glass, a thin coat of polyurethane, and another 0.375 inch sheet of glass. These are then sandwiched between two more coats of polyurethane and then outer caps of 0.125-inch polycarbonate. The total thickness is just over an inch.
Like traditional laminated glass, glass-clad polycarbonate is challenging to integrate into acrylic-style seamless systems. All pieces must be industrially water jet cut or hand-polished by the original manufacturer—a labor intensive process requiring special facilities. Like polycarbonate, it suffers from poor light-transmission and is susceptible to some crazing.
But glass-clad polycarbonate is a truly high-performance material. It’s available in many different make ups and can be layered up to any thickness, giving a variety of forced-entry and blast ratings, as well as bullet resistance levels all the way from Level 1 to Level 8 (easily stopping a burst from an AR-15 or AK-47). When layered with glass caps as the outermost surfaces, GCP makes a great choice for exterior applications: it holds up in high-traffic areas, weathers excellently and carries ratings for forced entry, explosive blasts and hurricane winds.
“Despite the expense,” Jim says, “we’ve been seeing increasing demand for GCP barriers. At one time, this was a product pretty much only used in government installations. Now it’s across the board. I think that reflects the situations and high-powered/multi-faceted threats so many businesses, schools, and communities find themselves facing.”