Clear plastic, often used to make eyeglass lenses and display cases, is almost always meant to be transparent. Over time, clear plastic may become scratched and dull, and therefore difficult to see through. You can polish your plastic items and make them clear and shiny again with special cleaning products and common household items.
Squeeze a bit of toothpaste onto a soft cloth or dip the cloth into a paste of baking soda and water.
Rub the cloth over your plastic in a circular motion.
Rinse your plastic with water and dry off with a soft cloth. If your plastic is still dull, you will need to use an etching compound.
Coat both sides of your plastic thickly with an etching compound. The acid in the compound will remove the outer coating of plastic along with any scratches and imperfections, leaving a polished surface.
Wait for five minutes and then rinse off the etching compound with water and dry your plastic with a soft cloth.