Acrylic is a clear plastic that resembles glass. It also has properties that make it superior to glass in some applications. Common brands of high-grade acrylic include Polycast, Lucite and Plexiglass.
There are two basic types of acrylic: extruded and cell cast. Extruded or “continuous cast” acrylic is softer, more easily scratched and the cheaper castings often contain impurities. Cell cast acrylic is the higher quality variation. This process yields greater consistency and can produce a sheet that is ten times stronger than glass at half the weight!
Acrylic is the material of choice for shower doors, bath enclosures, windows and skylights. It is many times stronger than glass, making it far more impact resistant. It also insulates better than glass. Acrylic can also be sawed, whereas glass must be scored.
Thick glass will have a green tint, while acrylic remains clear with a transparency rate of 93%. Acrylic is easily shaped as with bow-front aquariums. Chemical welding at the molecular level “melts” any seams into one piece of solid material. Seams that are welded and polished become invisible.
Though previous generations of plastic will yellow, turn brittle and crack over time, acrylics remain clear and durable. There is ample evidence of this claim including evaluations of WWII fighter planes that featured acrylic bubble-tops. Modern airplane windows are also acrylic. With reasonable care, acrylic will remain new looking regardless of age or exposure to sun. Although acrylic scratches more easily, unlike glass, scratches are easily buffed out.
Acrylic that is exposed to a direct flame will melt. Its performance under various conditions is predictable for any given formula. Extensive testing has been conducted on the question of flame resistance and, though acrylic will eventually burn, there are formulations that are actually used as flame retardant coatings.
Acrylic just over one inch thick (32mm) is bullet resistant. Many window enclosures feature bullet-resistant acrylic. Examples include the the Presidential motorcade, the booth-vehicle known as the Pope Mobile, bank teller stations and drive-throughs.