Hobbies Cars & Motorcycles How to Wet Sand Your Car's Primer or Paint Share PINTEREST Email Print Cars & Motorcycles Cars How Tos Buying & Selling Basics Reviews Tools & Products Classic Cars Exotic Cars Corvettes Mustangs Tires & Wheels Motorcycles Used Cars SUVs Trucks ATVs & Off Road Public Transportation By Matthew Wright Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. our editorial process Matthew Wright Updated June 25, 2018 Wet sanding is an amazing process that, when done properly, can result in a surface that's as smooth as glass. Whether you're talking about paint, primer, bare metal or anything in between, your car's body can be smoothed by wet sanding. Wet sanding, also known as color sanding, adds shine to a finished paint job. First, we'll talk about what you need to get the job done, then I'll tell you the finer points of the sanding process. Finally, we can get into the esoteric side of body finishing and sanding. 01 of 02 What You'll Need The only equipment you'll need is a spray bottle and sand paper. Matt Wright, 2013 A car or truck that needs some smoothin'Spray bottle filled with waterWet sandpaper in varying grits You can find spray bottles at just about any home repair store, box stores, or grocery store in the cleaning section. Be sure to buy a bottle that has an actual spray pattern. In other words, you don't want a spray bottle that throws a thick splash of water. Instead, you need more of a misty sprayed pattern that can saturate your work surface while you use one hand for spraying and the other hand for sanding. Choosing what grit sandpaper to use is important. If you start with a grit that is too coarse, you'll be creating more work for yourself and might be left with a thinner paint or primer coat than you wanted. Start with too fine a grit and you'll be sanding until your arm feels like it's going to fall off. A little experimentation will help. As a starting point, if you are sanding a coat of rough primer, you can start with a 400-grit sandpaper to knock down all of those little bumps. After some time with the 400 grit, you can move to a 600-grit paper to give yourself a nice, smooth surface to work with when you are painting the car. If you are wet sanding a finished paint job, you definitely do not want to start with a 400 grit sandpaper as it will be much too harsh and can ruin your paint finish instead of restoring it. For a finished paint job that just needs a little more smoothness and shines, starts with an 800, or even a 1000 grit sandpaper. Remember, when sanding anything, it's always important to take it slow. Let the sandpaper do the work, and don't apply too much hand pressure as this can cause grooves or uneven sanding. And we both know what that amounts to—more work! 02 of 02 How to Wet Sand Wet sanding require water and a back and forth motion. Matt Wright, 2013 With your materials chosen and bought, you're ready to get started. Unless you have a very nice garage with a drain in the floor and nothing at all stored in it, you will probably want to conduct all of your wet sanding outside. The water that runs off as you sand the paint's finish will be full of tiny bits of paint that can stain the floor and be difficult to clean up once dry. Before you begin it's always a good idea to wash your car to remove anything that you don't want to mix into the sandpaper-like wax, grit or other foreign matter. If you've been doing any bodywork there might be tape residue or other leftovers waiting to corrupt your efforts. With a clean car, you're ready to dive into the process of wet sanding. Essentially, wet sanding is the process of sanding a car with water. The water acts as a lubricant and vehicle to remove the paint dust that would normally just clog up the sandpaper and get in the way. Start by liberally spraying an area a couple of square feet in size with your water-filled spray bottle. Choose your coarsest grit (600 if you are sanding primer or bodywork, 800-1000 if you are sanding a finished paint job). Spray the paper itself, then start gently sanding the body of the vehicle. Unlike other types of sanding, wet sanding movements should be back and forth, in a straight line, rather than in circular motions. Don't apply too much pressure to the sandpaper. Sand back and forth within the same area, adding more water often. It can never be too wet. After a few minutes, run your fingertips across the sanded area and be amazed at how smooth it's become. Repeat this over the whole car, then repeat the process with your next finest sandpaper grit. When you're finished, rinse the entire car well to remove all of the sanding dust.