What Does
Safety Glass Mean?
Safety glass is glass that has been treated or designed to have special properties that can help prevent injuries, property damage, and break-ins.
Depending on the type of safety glass, it might be able to withstand fire, heavy impact, or break without shattering in order to prevent someone from getting cut.
Safety glass is typically used in places where standard glass would cause too much harm when breaking, such as windshields and skylights, as well as areas where security and heightened protection are a priority, such as police stations and toll booths.
Safeopedia Explains Safety Glass
Safety glass was patented by Edouard Benedictus in France in 1909. Benedictus created his version of safety glass by bonding a sheet of celluloid between two pieces of glass. By 1936, polyvinyl butyral (PVB) replaced celluloid as the standard material used in safety glass.
Common Types of Safety Glass
Laminated Glass
Laminated glass consists of two or more glass sheets joined together by a layer of PVB, which may be tinted or clear and has a thickness varying from 0.015 to 0.09 inches, or up to 0.12 inches for special applications. These layers are then fused together in an autoclave under controlled heat and pressure.
Laminated glass is shatter-proof. When it breaks, the PVB layer holds the glass together so it remains in one piece. Rather than shattering into pieces, cracks will form on the surface of the glass pane. This reduces the risk of injury when the glass breaks and also makes it more difficult to break through the glass.
Laminated glass is used in windshields, skylights, and in commercial applications such as banks or anywhere that money is exchanged. It is used for noise control, as less sound is carried through it. It can also be used to reduce glare or filter out ultraviolet (UV) radiation.
Tempered Glass
Also known as toughened glass, tempered glass is just that – glass that is treated with heat to provide it with more strength and impact resistance. Tempered glass can withstand approximately four times the amount of force that would be needed to break untreated glass.
While not shatter-proof, tempered glass does break safely, shattering into small pieces rather than sharp shards.
Tempered glass is produced by heating glass at a temperature close to its melting point, between 1,100 and 1,300 degrees Fahrenheit. It is then cooled with high-pressure blasts of cold air.
Broken tempered glass (source: Etsy)
Armed Glass
Armed glass is glass that has been reinforced with a metal mesh. It shatters like standard glass, but the mesh holds some of the glass in place to keep it from breaking away on impact.
The metal grill reduces overall visibility but does allow light to pass through.
Armed glass is typically used in outdoor structures and the roofs of industrial buildings.
Bullet-Resistant Glass
Bullet-resistance glass is made of multiple layers of laminate and glass, with polycarbonate material added between the glass layers. The polycarbonate plastic absorbs the energy from the bullet and allows the glass to flex back. The laminate and polycarbonate layers both help spread the bullet’s force across the entire surface of the glass, rather than concentrating it at the area of impact.
The thicker the bullet-resistant glass, the more impact it can withstand.