Bodywork requires skill and experience to complete a full repair from start to finish. This includes repairing dents or dings, preparing the surface for paint and then painting the car. To better understand the time and labour of doing car bodywork so you can learn to do it yourself, or at least understand what your collision shop is charging you for, you need to know the basics of each step.
There are several methods to repair dents in your car, but most bodyworks garages use only one or two methods. The most popular method uses a dent puller, or slide hammer, and a drill. This works on any size dent. Drill several holes in the dent in various places. Place the tip of the screw into one of the holes and screw it into place. Slide the weighted handle down near the dent and then quickly pull it back toward your body. Repeat this several times in each hole to pull the sheet metal into place.
Once the sheet metal is close to being flat again, use a grinder to grind away all paint and primer from the car in and around the dent. This also grinds the holes smooth and gets rid of the jagged edges. Apply a thick coating of body filler, such as Bondo, to the dent and surrounding areas. Do not apply body filler over a painted area because it won't adhere to the paint.
Allow the filler to dry for an hour and then sand it smooth with 120-grit sandpaper and a sanding block or a dual action sander. Sand until the filler is level with the surface of the surround metal. Sand the entire area again using 300-grit sandpaper.
Once the area is flat and smooth, spray it with a layer of primer. This can be sprayed from a regular automotive spray gun or from a spray can. Allow the primer to dry for at least 30 minutes. Sand the primer with a long sanding block and 300-grit sandpaper. Keep the block flat and smooth against the car. This allows the sandpaper to sand off the dark, outer layer of primer to reveal a lighter colour underneath. Low spots in the metal will show up as dark patches of primer since the flat sanding block won't be able to reach down into the low area. This means you need to grind the low area again, use more body filler, spray primer over it and then sand it again. This is the only way to get the smoothest surface possible.
After the car is smooth, go over the repair work once more with a layer of primer. This time use your hand to sand the area with 400-grit sandpaper. Wipe it down with wax and grease remover to remove oily fingerprints and grease.
To paint a car and get the best results possible, it should be painted inside a paint booth. If you don't have one, the best thing to do is to rent time in one at a local bodyworks garage. You need at least a few hours, so they may let you rent it after regular work hours or on the weekend.
Before painting the car, wipe it down with a tack rag to remove particles of dirt or dust that may have landed on the car. When spraying the car, use short, even strokes. Overlap each stroke slightly to achieve more even coverage. Apply three to six coats of paint, allowing each coat to dry for 30 minutes before applying the next. Do the same with the clear coat paint. Allow the car to dry for at least a full day before driving it anywhere.