To sand a car, an electric or air-powered sander is needed, in addition to 1200- and 2000-grit wet-and-dry sandpaper. Begin by using the sander on any panel of the car's surface areas. The sander should be moved along each panel in a circular motion.
A car should be sanded down completely to the bare metal, panel by panel, to achieve a smooth finish. Each of the car's panels takes approximately two hours to sand down completely. The corners and crevices of the vehicle may need to be sanded down by hand to achieve the correct finish. The car can also be sanded down without reaching the bare metal, as long as a smooth, even surface is achieved. This is done by using a fine-grade wet-and-dry sandpaper to finish the car during the last stage.
A process called wet-sanding is also used to sand cars to prepare them for painting or priming. The process is known as color sanding when it is used to give the surface of vehicles a glass-like finish after a paint job. When wet-sanding a vehicle, start with a 400-grit sand paper to sand away any bumps on the car's surface. Use a 600-grit sand paper to smooth the surface of the vehicle before painting.
To wet-sand a car after it's painted, use a 800- or 1,000-grit sand paper to add shine and smooth the surface of the paint. Remember to sand the surface slowly, and use a minimal amount of pressure to prevent grooves or uneven sanding. Wipe down the entire surface of the vehicle with thinner and a clean rag to remove dust when sanding is complete.