Acrylic - In the plastics industry most acrylics are polymers of methyl methacrylate (PMMA). Acrylics may be in the form of molding powders or casting syrups, and are noted for their exceptional clarity and optical properties. Acrylics are widely used in lighting fixtures because they are slow-burning or even self-extinguishing, and they do not produce harmful smoke or gases in the presence of flame. The most important properties for acrylic (PMMA) are its optical clarity, low UV sensitivity, and overall weather resistance. Acrylic is often used as a glass substitute.