The wonders of bulletproof glass

While the term “bulletproof glass” suggests a material which is 100% impenetrable to gunfire, this is actually not the case. No type of bulletproof glass can hold up forever against extremely powerful weapons, which is why the term “bullet resistant glass” is often preferred by those in the industry.

Bullet resistant glass is usually designed to prevent bullets from passing through an exterior wall into the interior, while allowing bullets to pass from the interior to exterior. Bullet resistant glass has a range of applications, including:

  • Security and military vehicles
  • Banks
  • Hospitals
  • Government buildings
  • Pharmacies
  • Police stations
  • Jails

Physical properties

While bullet resistant glass looks similar to regular glass, bullet resistant glass will hold firm even after the impact of several rounds of bullets, while conventional glass will shatter immediately. Although the manufacturing process varies from manufacturer to manufacturer, it normally involves layering a polycarbonate material between pieces of standard glass. This process is known as lamination and results in a glass which is more durable and thicker than standard glass (usually between 7 millimeters and 75 millimeters). The thickness of the glass generally depends on the application. For instance, a military base in a war zone is likely to need maximum protection from heavy weaponry, whereas a domestic building is unlikely to come under fire from such devastating weaponry, so the same level of security is not always necessary.

It is not just the thickness which makes the glass bullet resistant. As bullet resistant glass has multiple layers of materials designed to absorb shots, the impact gets spread over a larger surface area and the bullet is slowed down before it is able to to penetrate the glass. The glass panes do ultimately break when they are subjected to significant impact, but because of their tough structure, the glass will not fly apart, providing extra security to those behind the glass. Due to its thickness, bullet resistant glass weighs significantly more than standard glass, and when used in security vehicles, additional motors need to be installed to move the windows up and down.

New innovations

As you would expect for something which plays such a significant role in saving lives, technological innovations are constantly making bullet resistant glass even more effective. In recent news, it was announced that the US Navy has invented a type of bullet resistant glass made from a synthetic powdered clay known as Spinel, which is much tougher than standard bulletproof glass. Because of its durability, this new glass may be perfect for use in hostile environments where impact from gunfire is expected. Also, because Spinel does not block the infrared wavelength of light, it can be used for security camera lenses (or even for civilian applications, such as smartphones).

The Spinel glass is constructed using a manufacturing process called sintering, which involves crystal particles being pressed together into a layer. The Navy experts conclude that that this process produces a high quality of glass which is free from defects, and if it is subjected to damage, it will only chip rather than crack (due to the hard crystals in the glass). It has been suggested that this material could be used as transparent armour on military vehicles and perhaps even to protect satellites in space! Dr. Jas Sanghera of the U.S. Naval Research Laboratory states: “It’s a game-changing technology.

Tags: , , ,