Wet sanding is a cleaner alternative to regular sanding of drywall mud from remodeling and repairs. Wet sanding requires a special sanding sponge that replaces the traditional drywall sanding screens and blocks. The sanding sponge is used barely damp and requires frequent rinsing and wringing during wet sanding.
Wet sanding is a great alternative to dry sanding when repairs have been made to damaged drywall or plaster, as well as in remodeling that occurs in or near lived-in areas of the home. In wet sanding, the sponge is damp enough to significantly reduce the amount of sanding dust that becomes airborne. For this reason, persons with allergies living through a remodel or repair may well appreciate this alternative technique. In high-use areas of the home such as kitchens or baths, wet sanding can significantly decrease the mess that normally accompanies drywall repair.
When properly executed, wet sanding does not alter the number of coats of drywall mud required, but the process does take longer than dry block sanding. This is mostly due to the number of times the sponge must be rinsed and wrung out, and depending on the size of the area, the water may need to be changed as well. You can reasonably expect to sand about a 3-foot square (about one square meter) section before needing to rinse and wring your sponge.
here'd how to do it for your car:http://carpaint.blogspot.com/2005/07/how-to-wet-sand-and-buff-your-car.html