Cast acrylic is a synthetic plastic created by a chemical reaction between a catalyst and a monomer, resulting in a lightweight and transparent plastic product. Our White cast acrylic is strong, lightweight, and is available in a wide range of sizes, thicknesses, and colors. It has better thermal stability, higher resistance to crazing when exposed to solvents, wider thermoforming range than extruded acrylic. Cast acrylic has a better ability to be reworked hot and it is known for its superior surface finish and optical properties. Also cast acrylic is more scratch resistant than extruded acrylic. Cast acrylic is also preferred over extruded in applications that require machining, such as turning on Engine Lathe or milling/drilling. Extruded acrylic, with far less thermal stability, tends to melt and clog cutting tools. Even with slow speeds and much coolant, extruded acrylic does not produce the surface finish and tight tolerances achievable with cast acrylic. 12x18x1/8 White Acrylic Plastic sheet