1. To start the smoothing process, we need to give the primer a proper surface to stick to. This is done by sanding the surface with a dual-action (D/A) sander fitted with 80-grit paper. | 
2. You will need to hand-work the tighter areas so as not to knock off any of the body lines or put gouges in the plastic by tipping the D/A up on its edge. | 
3. Here it is in the halfway point. Again, we are not trying to smooth out the plastic, just rough it up. |
4. Besides the D/A and a spray gun, here are the products you will need. We used a Hutchins D/A and a SATA gun with a 1.4 tip. | 
5. Apply SEM Solve, liberally, to a clean, soft, lint-free cloth. Wipe surface to be cleaned to remove wax, tar, or any old contaminants that might prevent adhesion. Follow with a clean, dry cloth, frequently changing cloths. Whatever you do, don't leave the solvent-soaked cloth on a painted surface. | 
6. A coat of Bulldog will provide adhesion to all types of plastics, including polypropylene. It also has a long-term flex agent and can be used for interior and exterior applications. This is a crucial step when painting plastic because it will prevent peeling and make all this work you are doing last. |
7. Mix the primer per the instructions on the side of the can for temperature and humidity readings. We like PCL's Polyprimer because it can be top-coated with all types of finishes, acrylics, lacquers, synthetic enamels, and two-component urethane coatings. It comes in gray, red oxide, black, buff, and white, so you can match the paint color and cut down on the paint material you need to cover. And primer is cheaper than paint. | 
8. This primer needs a catalyst to dry properly, but it also means you have a smaller time window to spray it. Make sure you have everything ready before you mix the paint, because if this stuff dries in the gun, you will have a lot of time wrapped up in cleaning it out. | 
9. No matter how clean you think everything is, always use a strainer when pouring the paint in the gun. This will keep out any large clumps that will clog your gun. |
10. Set your air pressure around 30 to 35 psi, open the fan up, and start spraying the part. As you are spraying, if it looks nice and wet without running, you are set up perfectly. If it looks dry, cut down the fan a bit and spray a little slower. If that doesn't fix it, you might want to check the temperature, or your gun might be clogged. | 
11. Once the primer is dry, sand it with 220-grit paper and then 400. If the primer is smooth, you are ready for paint. If you sanded through to the plastic, you will have to shoot another coat of primer. | 
12. Here is a before and after of the sanding process. The sanded primer should be smooth to the touch and show no plastic. |
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13. With the sanding complete, the parts were taken in the booth, and Marcel sprayed the blue base and the slick clear. Again, with a SATA gun with 1.4 tip and a 35-psi air setting, he laid down two medium wet coats of clear. | |
THE FINAL WORD
The next day, the valance was color-sanded and rubbed before being reinstalled on the truck. This type of paintwork is perfectly suited to the beginner and home mechanic, because you can make a small booth in your garage. And if by chance you mess up the paint, the plastic valances are pretty cheap to replace.