Paint Preparation for Plastic Bumpers
Mark SimpsonDescription
Plastic bumpers on cars dates back to the 1960s when GM introduced the Endura bumper on the 1968 Pontiac GTO, a body colored design that is able to absorb low-speed impacts. Other manufacturers also began exploring alternatives to traditional metal bumpers. Early on they were primarily used as a styling element on sports cars or specialty vehicles. However, their popularity grew as automakers recognized the benefits of plastic bumpers in terms of cost, design flexibility, and durability.
In 1973 new bumper collision requirements made it mandatory for bumpers to withstand 5 mph impacts without significant damage to the cars. This led to numerous design changes that started with bumpers that stuck out way beyond the car’s body. Soon they discovered they could build a strong bumper design then cover it with a plastic covering that molded in seamlessly with the body. By the 1980s, plastic bumpers became mainstream features on many production vehicles. These covers provided both aesthetic appeal and protection to the underlying bumper structure.
Over time, advancements in plastic materials and manufacturing processes improved the performance and appearance of plastic bumpers. Thermoplastic materials like polypropylene became popular due to their impact resistance, recyclability, and ease of molding into complex shapes.
Despite all of these advances in bumper technology, paint preparation remains key to success when refinishing or initially painting these bumper covers. We Join Matt Roehrick of MCA Kustoms in Faribault, MN to give us insights into painting success. When it comes to preparing plastic bumpers for paint, there are several steps he typically takes to complete the process:
Cleaning: The bumper surface must be thoroughly cleaned to remove dirt, grease, wax, and other contaminants. This ensures proper adhesion of the paint.
Sanding: Matt explains, sanding the bumper surface “completely” is key to success, as paint is both a chemical and a mechanical adhesion to the surface and the factory coatings are known to fail if not properly prepared. He also adds, It’s an opportunity to smooth out any imperfections or scratches in the cover.
Priming: Applying a suitable primer specifically designed for plastic surfaces is crucial. The primer promotes adhesion and helps to prevent issues such as peeling or flaking of the paint.
Painting: Once the surface is properly prepared and primed, the bumper can be painted using automotive-grade paint in the desired color. Multiple coats may be applied to achieve the desired finish.
Overall, proper preparation of plastic bumpers before painting is essential to ensure a durable and high-quality finish that will withstand the rigors of driving and last for decades with proper care.
So today we're gonna be working on a plastic bumper cover and if you do any kind of auto body or refinish and repair, you know exactly what this is. This is an OEM style aftermarket application from bumper cover. Um All these bumper covers come sealed. We are actually gonna be scuffing the sealer to ensure that we get a good quality paint job and adhesion and that good quality paint job. So, and what we're gonna use is a 400 grit equivalent to a 400 grit piece of sandpaper, but this is actually like a 400 grit scotch right pad, which is nice and flexible so you can get in all your nooks crannies and crevices um of your bumper cover because these things can be a little complex to get in and all your edges and everything. And the reason why we're doing this is to ensure a really good quality paint job with really good adhesion. These scotch bright pads come in handy for a lot more things other than just scuffing bumpers. Um You end up scuffing quarter panels, et cetera with them, basically any component on a car that's gonna get painted, you can actually use these in the final stages of prep before paint as you scuff these bumpers. You'll see the Sealer kind of changes from almost like a dark gray to like a bluish gray. That kind of tells you that you've got in those areas. If you don't scuff one of these bumpers, the chances of your paint failure are very high. So you're gonna wanna make sure and get in all nooks crannies and crevices because these things do not hold paint unless they are prepped properly. So you're basically just looking for your area to be smooth, imperfection free and you're gonna wanna check this as you do it to make sure there's no imperfections in the sealer from the factory that provided the bumper as well. Sometimes there can and will be imperfections in the factory sealer. So you're just gonna wanna make sure that your whole entire surface has a good like clean scratch area surface on it for good paint adhesion. These bumpers are designed to be painted, they're not designed not to be painted. I mean, these things have to be prepped just like any other paint surface on a vehicle. This all needs to be prepped thoroughly, all nooks crannies, everything has to be taken care of just like you would prep any other component on a vehicle for paint that'll just help reinsure that you get great paint adhesion sealer. After you're done scuffing this, you're gonna wanna clean it with a good surface prep and then go to a plastic adhesion promoter and then tr it and then you'll be ready for your final process of base coat and clear.
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