How to Sand a Clear Coat Without Sanding the Paint
Automobile manufacturers have been clear-coating since the 1950s, but contemporary clear coats are harder and thinner than the original lacquer finishes. Usually composed of a two-part urethane system, a contemporary clear coating not only protects the undercoat from impact damage, but it also gives UV protection to prevent color fading. Scratches which don’t extend through to the bottom coat can usually be removed by sanding, but you have to be careful to not remove too much of the clear coat, or you’ll undermine its ability to block UV rays. You need to wet sand clear jackets with very fine sandpaper.
Soak a sheet of 1200-grit wet/dry sandpaper in plain water for 10 minutes. As soon as it’s soaking, use masking tape to areas you don’t wish to sand, like moldings and panel borders.
Eliminate the sandpaper out of the water and then wrap it on a sanding block. Wet the area you are likely to sand by spraying water from a spray bottle.
Sand by employing a firm, steady pressure to the sanding block and moving in straight lines so that you may observe the sanding scratches. If you are sanding out a scratch in the end, move the paper in a 45-degree angle to the scrape. This will allow you to differentiate the sanding scratches against the one you’re attempting to remove.
Keep the surface moist while you’re sanding by often spraying it with water. When the water begins to turn milky, stop sanding, then wipe the surface off and dry it with a blow-dryer. Examine the surface for signs of wear-through until you continue.
Remove scratches left from the sandpaper by following up with 1500-grit sandpaper and then 2000-grit sandpaper, wetting the paper along with the surface in the exact same manner as you did before. When you’re finished, the surface will have a uniformly dull, chalky appearance.
Spread polish on the area you sanded and buff it up with a buffer fitted with a wool or foam pad to renew the glow.