Some headlights cannot be restored regardless of the method used. The Ice-9 System is designed to quickly restore about 80% of the lights you run across on a daily basis. Lights to avoid would be lights with extreme clear coat peeling and extreme crazing (crazing is internal stress cracks caused by heat). Crazing cannot be removed by any method. However, the Ice-9 Liquid Titanium Glaze will hide some crazing. Some headlights will have internal hazing on the inside of the light that happens when the gasket on the headlight is compromised and allows dirt and moisture on the inside of the lens. This internal hazing cannot be removed. The good news is that with the Ice-9 System, it only takes a few minutes to figure out if a light has internal hazing.