This page is not intended to teach you everything you need to know to paint your own car. Its goal is merely to identify the basic steps, and some useful tips and tricks to help make the job of painting your car more successful. Before you get started, check into your local environmental regulations regarding spraying paints at home. Even if you decide not to do the entire job yourself, you can still get a better paint job and/or save a lot of money by doing the prep work yourself – using the following information.
One of the best tips we can give you is to remove as much of the trim as possible from over and around the areas to be painted. If you’re doing an exterior-only paint job, this means trim, bumpers, mirrors, grille, and other exterior items. If you’re painting all or part of the interior, you’ll have a lot more to remove.
The next step is to thoroughly clean every nook and cranny (not just the painted areas, but also any areas that dirt could be dislodged from while painting. Start with detergent, and follow that with a quality wax and grease remover on areas that will be painted. Then apply a thick layer of tape to any areas like the windshield molding that may not have been removed. This will protect these areas from the sanding you’ll be doing next.
Sand down the old paint (at least to the original paint level) using a dual-action (DA) orbital air sander, which is less likely to dig in like other sanders. In general, use sandpaper finer (a higher number) than 120 grit. You may need to use coarser grits for removing rust or excess fillers. We’re not going to get into the details of body repair (welding, fillers, etc.) in this section, but obviously, these repairs would have to be made if there is damage or rust. Even minor pinholes have to be properly repaired. Avoid the temptation to use large amounts of acrylic glaze. The surface glazes over quickly, but thick areas take longer to dry and often shrink back a lot.
After a thorough cleaning of the car (and the mess you just made), it will be time to mask off the car for the primer/filler coats. Masking is also one of the most important steps for a high quality paint job. If you’re not painting the trunk, engine compartment, etc, you’ll have to take special care in masking off these areas from overspray. Using weatherstrip material or even weatherstrip tape can help to seal the joints between body panels to prevent spray from entering. Use a thin plastic tool such as a plastic knife or filler spreader to force masking tape under the edges of any remaining trim such as around the windshield or window moldings. Make sure you also mask off the tires and wheel wells, and form an apron around the underside of the car to keep overspray off of these areas.
Now do one more wipe-downs just prior to applying the primer/filler coats. In addition to applying several thin coats of a quality primer/filler, we recommend applying a guide coat. This is a thin sparse coat of a contrasting color of primer/filler peppered on top of the last full primer/filler coat. As the car is block sanded (see next paragraph), the guide coat will be removed quickly from areas that are high. In low areas, the guide coat will remain visible. You will need to use your judgment on whether to sand the high areas a bit more, do additional body work, or (for very minor low areas) add a couple additional coats of primer/filler and a guide coat.
Wet sanding of the primer is generally done with 400 to 600 grit wet/dry sandpaper. Use a soft foam pad wrapped with the paper for sanding curved areas. For flat areas, use a rubber pad. Use a bucket of warm clean water and a sponge to constantly rinse the area and the sandpaper.
Although we didn’t mention it, by this time you’ve probably removed most of the soggy masking tape and paper used to mask off the car. If not do it now. When done, clean the car thoroughly with clean water, and wipe the car dry to prevent contaminants in the water from being left on the primer. If you’re not going to color paint the car immediately, or if you’re going to transport the car to a different location for the final paint job, you must prevent getting any oils or contaminants on the surface. A coat of primer sealer is highly recommended if there is any chance of the car getting contaminated. Remember all the work you did to mask off the car. Well, it’s all going to have to be done again. Also make sure that there is absolutely no primer overspray on adjacent areas.
For the color coats and clear coats, follow the manufacturers directions in thinning and applying the paint. In general, start at the top and work your way down. Keep the gun 10 to 12 inches from the surface and as parallel as possible. Overlap the spray pattern 33% to 75% of the previous pass. Use medium wet coats that look smooth and glossy, but don’t run. Start each stroke and pull the trigger before you get to the area to be painted, and don’t stop or release the trigger until you’re past the area being painted.