Acrylic thermoplastics (commonly called plexiglass) are available in cast or extruded sheet, rod and tube. Extruded plexiglass is the more economical alternative to cast acrylic. Cast plexiglass has superior optical and surface qualities, and is available in a wide variety of colors, textures and formulations. Cast acrylics are strong, stable, weather resistant and thermoformable. Transparency, gloss and the dimensional shape of acrylic are unaffected by years of exposure to the elements and corrosive atmospheres. Plexiglass withstands exposure to light from fluorescent lamps without darkening or deteriorating. Special UV resistant formulations may be available. UV absorbing grades are commonly used for document preservation in museums and various photographic applications. Coated plexiglass offers increased abrasion resistance. The optical clarity, light transmission, light weight and toughness of acrylic makes it a good substitute for glass without the threat of shattering.