A common use of ultra fine grit sandpaper is to spot-treat larger scratches in a car's paint or clear coat. "Wet-sanding" makes scratches disappear by lowering the level of the surrounding clear coat or paint to match the depth of the scratch. The only problem is that the wet-sanding leaves its own scratches behind. But these tiny, shallow scratches are easy to remove even if they cover a large area. All they need is a little filler and polish and they'll disappear for good.
Wash the sandpaper-scratched area with a large car sponge dipped in a bucket of soapy water. Rinse it clean with water and dry it thoroughly with a clean, lint-free towel.
Apply roughly one teaspoon of rubbing compound to a terry cloth towel. Rub the rubbing compound onto the scratched area in a circular motion until the scratches are no longer visible. Use a soft cloth to wipe away any residual compound.
Wash the area with a large car sponge dipped in a bucket of soapy water, then rinse it clean with water and dry it thoroughly with a clean, lint-free towel.
Apply a quarter-sized amount of swirl mark eliminator onto a microfiber polishing pad. Buff the area until all of the swirl marks are gone and the swirl mark eliminator is dry.
Seal the deal with a bit of car wax. Use a high-quality abrasive-free wax such as Carnuba wax. Apply a few drops to a small, soft car sponge and use a circular motion to spread a thin layer of wax evenly over the area. Leave the wax on the car for 5 minutes to allow it to haze, then wipe the wax away with a clean, soft towel.