Bullet-resistant glass, commonly known as bullet proof glass, is nevertheless extremely resistant to impact. However, a usable thickness of bullet-resistant glass generally can't stop a bullet from a high-powered rifle. This type of glass is actually a series of glass layers that includes some strong transparent material. Bullet-resistant glass is made in an industrial process that consists of several specific manufacturing steps.
Cut tempered glass sheets into the desired dimensions. Tempered glass has the same composition as normal glass but has been treated with heat to make it more impact resistant. This type of glass is very hard and will cause a bullet to flatten out when it strikes the glass.
Laminate the glass sheets with plastic. This layer of plastic does little to resist impact and serves primarily as a base for the epoxy resin that will be applied later.
Make polycarbonate sheets in the same shape as the glass sheets from Step 1. These sheets may be constructed from a variety of specific materials with brand names such as Armormax, Cyrolon, Lexan, Makroclear and Tuffak. These sheets are not nearly as hard as the glass but will provide the impact resistance to a bullet.
Bond alternating layers of laminated glass sheets with polycarbonate sheets. Glue these sheets together with some type of ethylene-vinyl acetate, such as polyvinyl butyral or polyurethane.
Make this composite material a total of three inches thick for most applications. This is generally the maximum thickness that's generally referred to as bullet-resistant glass. Thicknesses of four and five inches are known as armored glass and are used primarily in combat vehicles.