Volume 34, Number 7, July 1999


Which is Which?

Choosing the Right Bullet-Resistant Glazing Materials for the Job

by Fred Gebauer

Here’s a situation you probably encounter from time to time: You have a customer who is interested in security glazing products. The customer is relying on you to choose the materials most appropriate for the job. You know what some of the options are, but you’re not sure which one is best for your customer’s application.

The above example isn’t unusual. As gun violence increases in the United States, the demand for security glazing is on the upswing. At the same time, security products on the market are becoming more diverse, making it difficult for contractors and architects to keep their product knowledge current. This article will present an overview of the security glazing product options in each of the first three Underwriters Laboratories (UL) ballistic rating levels.

About UL Ballistic Ratings

UL tests glazing and framing products for resistance against a variety of ballistic attacks, and rates them accordingly. UL levels 1, 2 and 3 are rated to resist attacks by .9 mm, .357 magnum and .44 magnum weapons, respectively.

Level 3 is the highest class of protection used in the retail market. UL also issues ratings for levels 4 through 8, which typically apply to government and military applications. The right solution depends on the client’s protection requirements and on the nature of the application.

About Security Glazing Products

The security glazing industry offers a variety of products made of glass, acrylic, polycarbonate or some combination of the three. The glossary on page 41 gives a general description of each type of material.

Each product has advantages and disadvantages. Some materials are more appropriate for exterior use, while others should be used only on interior projects. Some are easier to fabricate than others. Some offer better optical clarity or abrasion resistance.

All of these factors are spelled out in the tables on page 41, along with recommended applications. Keep these charts as a reference, so the next time a client consults you about security glazing options, you’ll know where to turn for information.

Fred Gebauer is director of business development at Insulgard Corporation, a national manufacturer and distributor of integrated bullet-resistant security systems.


Acrylic, coated: A single layer of cell-cast acrylic material with an abrasion-resistant protective coating.

Acrylic, uncoated: A single layer of cell-cast acrylic material without a protective coating.

Composite system: A composite material composed of polycarbonate and glass, with a layer of air in between. Designed for use in exterior walls, with glass facing the outside and polycarbonate facing the interior.

Glass-clad polycarbonate: Material made by laminating polycarbonate and glass together.

Laminated glass: Material made by bonding multiple plies of laminated glass together. A thin layer of polyvinyl butyral is sandwiched between the layers of glass.

Laminated polycarbonate: Material made by laminating multiple plies of polycarbonate together.

Laminated polycarbonate/acrylic: Material made by laminating polycarbonate and acrylic together.


Copyright 1999 Key Communications, Inc. All rights reserved. No reproduction of any type without expressed written permission.