Windshields and especially the rear window on trucks and SUVs are exposed to harsh conditions. Run your fingers over the glass. If it doesn't feel as slick as ice, it needs claying. Glass Cleaning Clay is the perfect glass prep before polishing. Clay also works on a variety of smooth, hard surfaces such as glass shower doors, chrome, stone, ceramic tiles, synthetic stone, and quartz surfaces. Speed Shine® is the proper lubricant to use with clay along with our PFM® Detailing Towels to buff the surface dry.