Paint Polishing by Sanding One More Time

A show-quality paint finish requires plenty of work before and after the topcoat is applied. You've probably heard fellow street rodders say that the key to an excellent paint job is preparation, and that's very true. If the body isn't flawless, it's a waste of time to apply the paint. A high-gloss paint finish will magnify every wave and ding in the body. Getting the body perfect is just one step in the overall process. Applying the paint properly is the second step, and it requires professional spray equipment, high-quality paint products, and an experienced person to apply the paint. Using the acrylic urethane paints currently available, it's very easy for an inexperienced painter to turn a car into a runny mess. Even an experienced painter can end up with a run or sag in the final paint application. That's where step three comes into the picture. Many of the urethane paints don't have to be polished for a shiny finish, but most will have a certain degree of "orange peel." In other words, the overall finish is shiny, but the surface is still a little bumpy. In order to get the mirror-smooth finish seen on top-quality show cars, the paint has to be sanded and polished after it's applied.

Just when you thought all of the sanding was finally finished, we're here to tell you that even more is necessary after the car is painted. The smooth surface found on show cars is achieved by sanding the topcoat flat before any polishing can be done. The quality of the sanding done on the paint will be reflected in the final outcome of the finish. The sandpaper used for the painted surface is a much finer grit. Some polishing experts start out with 600-grit wet and dry paper and work their way to a much finer paper, such as 1,500-grit, before any buffing is done. Some prefer to start out with 800- to 1,000-grit and work their way to 2,000-grit paper. We've tried both methods and had excellent results. On this '29 Ford roadster, we started out with 1,000-grit wet and dry and worked our way to 2,000-grit. As we progressed, we also sanded the car with 1,200- and 1,500-grit to achieve a flawless finish. In these finer grits, the paper becomes the first step in the polishing process. When you look at the sanded finish, it actually reflects more every time you change to a finer paper.

We've seen some people scratch the surface of the paint with 1,000-grit sandpaper, then buff the paint. You will get a shiny finish by doing this, but the orange peel, although somewhat subdued, still remains. The key to a great paint finish is color sanding the car until all of the orange peel has been removed. This can be just as tricky as applying the paint. First of all, when the paint is applied, it's a good idea to clearcoat the surface with plenty of material, especially over body lines and sharp edges. You don't want to sand through the clearcoat when you are color sanding the car. This is very easy to do on sharp edges and body lines. It's a good idea to mask them off to eliminate the chance of sanding through. Color sanding on open body panels should be done with a soft block to keep the surface flat and to work on the high spots that create the orange peel effect. If you're sanding close to body lines and in small areas, you can sand them by hand.

Color sanding is tricky to get the paint surface perfectly flat, and with fine-grit sandpaper it becomes very time consuming. If the paint was applied smooth to start with, only a small amount of color sanding may be necessary. If the paint went on with a lot of orange peel, it may require a great deal of sanding. We usually sand panel-by-panel, starting with 1,000-grit and working our way to 2,000-grit. When we feel the surface is flat, we rub out a spot with compound to get it shiny, then check the surface. If it's flat, we continue to buff out the panel. If we still see small bumps on the surface, we continue to color sand and check the surface. When that entire panel is flat, we buff it out and move to the next panel. If this sounds time consuming, it is, but it makes the difference between an excellent paint job and just a mediocre one.

We've used a variety of polishing systems for buffing out a car, and have had good luck with 3M's polishing compounds. The first step was to use Perfect-It Rubbing Compound, which brings up the initial shine. For the second step, we used Imperial Microfinishing Compound, which is a milder compound and swirl remover. Our choice for the third step was Perfect-It Foam Polishing Pad Glaze. This step removes any swirls in the paint, because the foam pad doesn't leave marks. The final step consists of a high-quality glaze such as 3M Hand Glaze or Meguiar's Mirror Glaze #7, which brings out the final shine. We usually apply several coats of hand glaze before any wax is used. We should point out that there are three different 3M buffing pads that are used with the Perfect-It system: one for the compound, a softer pad for the second polishing compound, and a foam pad for the swirl remover. They are Velcro-backed and work with a special hub attachment on the buffer.

The car we are currently working on is a '29 roadster that we just painted light chrome yellow toner. We painted it with PPG Deltron basecoat covered by NCT clearcoat. When the car was painted, the weather was perfect, so the final finish laid down with a minimum of orange peel. We'll show you some of the steps we took to get the body looking good.