Bullet resistant glazing isn’t just a type of glass that is magically able to withstand ballistic impact. There are different methods and materials used to obtain the ballistic integrity including different plastics, innerlayers, glass and a combination of all three. Advancements in the quality and clarity of these products has allowed for more flexibility in design and implementation of architectural security in nearly any application.
While no bullet resistant glazing system is fully “bulletproof” there are plenty of options out there that offer different levels of protection. It is important however to know the characteristics of the different options in order to find the best fit for your application. Several factors influence which transparencies are used in which applications. These factors include level of protection, location, application, clarity requirements, weathering limitations and design requirements. Let’s take a look at the different options for ballistic glazing and identify the advantages and disadvantages of each.
First, let’s start with all-plastic products which include bullet resistant acrylic and polycarbonate. Since they are both plastics they are equally light-weight in comparison to glass products and easy to fabricate, cut, shape, notch, drill and fasten. Here are some additional characteristics, both good and bad, of all-plastic bullet resistant products.
Acrylic
Bullet resistant acrylic sheet can be monolithic (one sheet) or laminated (multiple layers laminated together) depending on the level of ballistic protection. Pros include affordability, water like clarity and the ability to flame polish the edges for a very crisp and seamless appearance. The acrylic also includes UV inhibitors to stop from yellowing and abrasion resistant coatings to help guard against scratching. Some drawbacks to acrylic include that when impacted by a bullet, the acrylic will shatter and the bullet can ricochet. Also, the material is only available in lower levels of protection including UL752 Levels 1-3 and the material, even at UL level 1 is fairly thick at 1 ¼”. Lastly, although acrylic does have scratch resistant coatings available, acrylic is still a plastic and not as durable as glass.
Polycarbonate
Bullet resistant polycarbonate sheet is always laminated (multiple layers laminated together). For this reason, and the fact that polycarbonate has a slight tint, polycarbonate does not have the water clarity of acrylic. It does however provide ballistic protection at the thinnest gage available. Laminated polycarbonate can meet UL level 1 bullet resistance at just ¾”. Also, due to the softness of the polycarbonate, it will actually catch the bullet in the sheet and the polycarbonate will not shatter and the bullet will not ricochet. As with acrylic however, polycarbonate is a plastic and although the outer surfaces come with a mar-resistant coating, the material is also not as durable as glass.
Speaking of glass, let’s take a look at all-glass and glass clad polycarbonate products that are bullet resistant. All glass products are multiple layers of glass laminated together with PVB inner layers whereas Glass-clad polycarbonate products combine layers of glass with layers of polycarbonate with the innermost layer being that of polycarbonate to stop spall.
Laminated All-Glass Product
The biggest advantage to an all-glass makeup is the fact that the interior pane and the exterior pane are both glass. This provides excellent durability for both surfaces with regard to cleaning, weathering and scratching. The glass will not scratch. However, because it is an all-glass makeup, the material is generally very thick and much heavier than plastics or glass clad polycarbonates and it can be difficult to find framing that will accept the product. There is also very limited fabrication you can do to this product and it is not available for higher levels of bullet resistance. All-glass makeups are only available in UL752 Levels 1-4.
Glass-Clad Polycarbonates
These make-ups are most commonly used for ballistic protection, particularly for exterior applications and where higher levels of ballistic protection are required. Glass-clad products are available in UL752 Levels 1-8 and can also be insulated for better thermal performance. Glass-clad products are lighter than all-glass products of equal levels of protection, but heavier than plastic products. Also, because these makeups include glass, they are not easy to cut or fabricate and need to be made to size. Lastly, because the interior or safe side of this product is polycarbonate, it is not as durable as a glass surface.
If you’re looking to learn more about bullet resistant glazing materials or find the option that fits best with your own building, contact Insulgard today. We offer a variety of bullet resistant windows, doors, and other protection systems that can be made to perfectly suit the needs of your facility.
