How to Paint Your Own Car

Second year student Jason Park was elected to spray the first coats of sealer. To prep the car, he hit it again with another blast of compressed air, wiping it with a tack cloth.

Because several areas of the car were sanded to bare metal, those spots need a coat of etching primer or a Direct To Metal (DTM) epoxy primer sealer like DuPont's V2970s. We went with the DTM sealer because we had a little left over from the last car we painted.

We originally planned to just spray the areas of bare metal, but since we had enough of the DTM sealer, Park sprayed the whole car with one coat using a DeVilbiss High Volume Low Pressure (HVLP) spray gun and a 1.4 fluid tip.

Park demonstrated the proper spray technique. Hold the paint gun perpendicular to the surface being painted, at a distance of about the width between the tips of your thumb and pinky as if you were making the "hang-loose" sign. Overlap each pass by 50 percent, making long passes across the width of each panel or sections of panels, as in the case of the side of the car.

Next, Park sprayed two coats of DuPont 2804s high solids urethane sealer. Sealers perform many functions. They act as a barrier between the new and old paint preventing swelling and lifting, they are also an adhesion promoter, and they make the car a uniform, neutral color. This is important when doing a color change like we are. If our metalwork was superstraight, we could topcoat directly over the sealer without an additional layer of primer. And since paint is semitransparent, painting over a neutral grey background would ensure even color over the whole car.

In order to eliminate the appearance of any remaining ripples and waves in our sheetmetal, the students each took a turn at spraying Alsa's APs-22712 urethane primersurfacer. These types of primers, also called buildup primer or filler primer, are meant to be sprayed on in relatively thick coats and sanded flat once they've cured. They level out as they cure, filling sand scratches and small nicks and dings. The students sprayed the car with two coats of primer using a 2.5 fluid tip in the spray gun. Compared with the technique used to apply the sealer, basecoat, and clearcoat, this is like spraying with a fire hose. Prior to being removed from the paint booth, the car was again sprayed with a light guidecoat, the reddish splotches you see in the photo.

After allowing the primer to cure for 24 hours, the students began wet-sanding the primer, doing the whole car with 220-grit sandpaper, and then repeating the process with 400-grit. Here sergio Ortiz shows the proper sanding technique. notice he's using a long sanding block and moving long, broad strokes in an X-shaped pattern. This is to prevent sanding grooves and gouges into the primer.

If this final step before topcoating sounds like a lot of work, you're right. However, Ferre says this is the most important step in refinishing a car. "It's your last chance to get the car straight before you paint it." To get it right, sand until the guidecoat is gone, constantly checking your progress as you go. When you get to the point where you just start to see the layer underneath the primer (in this case, the gray sealer), you're done.