When buying acrylics, remember that transparency, gloss and dimensional shape of acrylics are virtually unaffected by years of exposure to the elements, salt spray or corrosive atmospheres. These materials withstand exposure to light from fluorescsent lamps without darkening or deteriorating. They ultimately discolor, however, when exposed to high-intensity UV emission from light below 265 nm. Special formulations resist UV emission from light sources such as mercury-vapor and sodium-vapor lamps.

Colorants can be added to produce a full spectrum of transparent, translucent or opaque colors. Most colors can be formulated to give long-term outdoor durability. Clear acrylics are normally formulated to stop the ultraviolet radiations below 370 nm wavelength.

Mechanical properties of acrylics are high for relatively shorterm loading. High stresses can be sustained safely for short periods, but for long-term service, tensile stresses must be limited to 1,500 psi to avoid crazing or surface cracking.

Acrylic plastics are among the most scratch resistant of all thermoplastics. Toughness of acrylic sheet, as measured by resistance to crack propagation, can be improved by inducing molecular orientation during forming. Jet aircraft cabin windows, for example, are made from oriented acrylic sheet.

Special ultraviolet-absorbing grades are used for document preservation in museums and for various photographic applications. Specially formulated acrylic sheet is available for deeply formed components such as tub and shower units which are subsequently backed with glass-fiber reinforced polyester.

For more information, contact Mike at Ultra Acrylic's, Inc.