Aerodynamic Auto Parts
Not long ago, I had an unfortunate parking lot accident. A tired employee backed into my pride and joy, crumpling and tearing the plastic bumper cap on my car’s rear. A $4,200 repair turned out perfect, but it left me asking questions about the use of plastics on cars.
Most modern cars use plastic bumper systems and fascias made of Thermoplastic Olefins (TPOs), polycarbonates, polyesters, polypropylene, polyurethanes, polyamides, or blends of these compounds.
Often, glass fibers are added to provide more strength and structural rigidity. Plastics allow automotive engineers to have a lot of freedom in styling, building and placing components.
The Problem with Plastics
Plastic lends itself to combining several complex parts into a single, integrated piece, such as a bumper cap or spoiler. From bumpers to door panels, plastics give car designers and engineers the freedom to create shapes and designs that otherwise would never be possible.
With all of their benefits, plastic body parts do have limitations and drawbacks. I’ve discovered that painted plastic body parts are easily stained and dulled. To understand why, I researched the process of painting plastic bumpers and how it differs from painting metal body panels.
I have long known that it’s necessary to add a “flex agent” to paint that will be applied to plastics. The flex agent allows the paint to move with the plastic part without cracking or delaminating. What I did not understand is how the flex agents work and why painted plastic parts are so susceptible to staining and dulling.
Paint flex agents cause the cured paint to be more porous. In essence, the flex agent makes the paint foam, creating microscopic pockets. These pockets allow the paint to remain spongy and flexible. Most of the pockets are deep in the layers of paint, but some float to the surface. The flex agent also causes the paint to remain soft. Paint on TPO parts resists chips very well, but it will dent (small pock marks) from road stones.
The porosity and softness afforded by the flex agent create a couple of challenges. First, the paint does not resist stains as well as paint without a flex agent. Second, the flex agent paint cannot be buffed or polished with anything more than the finest polish, or the finish will be ruined. Buffing does not increase the gloss on this paint as it does on a hard paint finish; it smears it.
I’ve seen cases of botched repair jobs, where an inexperienced painter used a buffer to blend paint, and put permanent buffer burns and smudges in the bumper cap. All too often car owners use a rubbing compound on their soft plastic bumper caps to remove bug stains.
It’s so true that the paint dulls and never returns to full gloss. I have also noticed that etching from hard water and bird droppings is much worse on the painted plastic parts.
Auto Body Shop Tango
No one likes the thought of taking their car to the body and paint shop. Horror stories abound. How many times have you listened to the stories about swirl marks, paint that didn’t match after 3 months, over-spray on the rest of the car, and so on? I could go on and on with some of the stories I’ve heard, even longer with what I have experienced.
It’s unfortunate that for every good paint and body shop available, there are probably three mediocre shops and two bad ones. When the day comes that you need to take your shining beauty to the painter, you need to be prepared. You need to know what to expect before you get there, and know what questions to ask to qualify the shop and the painter.
Just as important as qualifying the paint and body shop is understanding what damage requires a body shop repair. Just like alternative medicine for humans, there are some great alternatives to going to the body shop for small nicks and dings.
No one likes to think about it, but when a repair facility bungles the job, you need to know what remedies you have available to you. The unfortunate thing about paint and bodywork is, you may not know there is a problem until days, weeks or months later. What can you do?
Good Car Painter, Good as Gold!
There are several stages to paint and body work. The first step is repair. If your car was in a minor fender-bender, it may require some parts removal and replacement. Common replacement parts include lights, bumper caps, hoods, spoilers, trunk lids, quarter panels and doors. Virtually every component of your car’s body can be replaced, and all manufacturers make the necessary replacement parts.
If your car was in a serious accident, it is often necessary for the repair facility to make repairs to the internal, structural system of your car. This often includes the vehicles’ chassis and frame.
For these repairs, you must first seek the counsel of your insurance company. Your insurance company should be intimately involved in all major repair work to your car.
The second step is preparation. Preparation has many facets, but you can think of it as perfecting and protecting the bodywork for painting. Body shop technicians perfect bodywork by cleaning, straightening and aligning panels to be painted.
Different shops have different methods for perfecting small dents, dings and ripples, but all body shop technicians use fillers. The quality of body fillers and application methods varies widely, and you should inquire.
Once the bodywork is complete, the car body technician prepares the body panels to accept paint. This involves the use of sanding papers and paint primers. The body shop technician is also responsible for masking your car, leaving only the parts to be painted exposed.
The third step is painting. In most shops (small shops are different), the painter does not do bodywork, and the bodywork technicians do not paint. so it’s really the painter who determines if a car is ready to be painted. A good painter will scrutinize the preparation work, because bad preparation will make his work look bad.
The smallest details can make a paint job look bad. For example, if the car body technician uses a grinding disk in the repair process and does not completely remove or fill all of the circular grinding marks, they will show through into the final paint.
Likewise, pinholes in filler are a common prep problem, as is neglecting to feather repairs for a smooth blend. The painter should find all of these problems and reject the car if it’s not ready.
The fourth and final step is buffing and blending. It’s my belief that a good painter rarely needs to buff his paintwork. If a car requires buffing because the paint is oxidized or slightly faded, it should be done prior to painting in order to correctly match the repair color and finish.
Auto Body Shop Horror Stories
There are lots of stories where a car owner will say, “Look what the body shop did to my car!” Believe me, I have my own learning experiences.
My horror story takes place in Sacramento, California, where I was working for the state on a child support enforcement project. For the two years I was working on the project, I left my BMW M3 in Sacramento for local transportation.
Even though my daily drive to work was short, the Sacramento roads have a lot of debris, so the front of the car had heavy road stone damage. At the end of the project, I decided I would have the M3’s paint repaired prior to transporting the car down to Los Angeles.
Not being a Sacramento resident, I did not have a relationship with a painter, so I consulted the local dealer. As it happens, the same family owns the Porsche dealership in Sacramento, and I had seen their paintwork.
It was perfect in every way. So, I assumed I would get the same quality of work from the BMW facility. What I did not realize is that they send their paintwork out to local shops. Bingo! Mistake number one on my part.
Timing being what it was, my M3 was not ready until the day I was packed up and heading out of town. The paint shop had delayed the work by 3 days. When I got the car back, it was filthy, but on first inspection, the paintwork looked pretty good. That is, until I loaded the car on the transport trailer.
On closer inspection, the paintwork was horrible. Three problems stood out. First, the repair facility was lazy and did not mask off or remove the plastic brake cooling ducts. So the ducts, which are supposed to be black, were now silver. Second, the lower cooling intake vent was matte black from the factory, but the painter sprayed it silver instead of masking it off or repainting it black.
Worse, however, someone used a sanding disk and left deep grinding marks on the front spoiler. Strike three, the painter’s work was obviously not great, because they used a buffer on the paint and stained all of the black rubber and plastic parts with silver paint from the buffing wheel.
Needless to say, I was furious, and they knew it. What could I do? I was headed out of town. The repair bill was $1,400, and they wanted a personal check or cash. Sorry, guys, here’s my credit card. By the way, never pay for a repair by cash or check.
On my way out of town, I called my credit card company and disputed the bill. My second call was to the paint shop to voice my displeasure and to tell them I had stopped payment. They filled my ear with some colorful metaphors.
After multiple calls and several hours of negotiating back and forth, the owner of the paint shop agreed to reduce the bill by $800, which is what it would cost to replace the parts they had ruined and repaint the center intake area black again. I wanted compensation for my time, but he told me to go to a hot vacation spot down under.
Do-It-Yourself Paint Repairs
I’m not going to talk about doing your own repairs. That’s another book all to itself. However, I know that many of you like to be involved in the repair work. Indeed, for the best results, you must be involved.
If your car needs to go to the paint and body shop, you can do a lot of preparation work yourself that will help make the repair work better. For example, cleaning the car and removing trim is an important step, and most body shops hate doing it or refuse to do it.
In almost all cases, you will get a better repair if you remove the trim from the panels to be repaired and painted. Most body shops simply mask around the trim (lights, side markers, door handles, chrome bumpers, etc.) because it takes too much time to remove it. There is also some risk in removing and reinstalling trim.
The problem with masking trim is that there is always a masking line, leaving a clear sign that the car was painted. Also, don’t forget what some buffoon did to my bumper trim with a buffer. If you take the time to remove small trim parts, the end result will be much better.
Clean your car completely before taking it in for repair. The most important task is to remove all waxes, sealants, polishes and silicones from the repair area. Realize that the body shop technicians will use Prepsol (a paint preparation cleaning solvent) to wipe down the areas to be painted, but how well do you think they will actually clean?
If you have wax in the deep crevices between a door and fender, do you think they will take the time to scrub it out with a toothbrush? Don’t fool yourself. Do the deep cleaning yourself. Make sure everything is cleaned, even down to the lowest part of the body.
Get Involved with Car Repairs
When you take your car in to a shop for a repair, you’ll want to meet two people, the manager and the painter. Let the manager know what you’ve done to prepare the car for their work. He may shake his head and tell you it wasn’t necessary, but you know better.
He may even warn you about problems reinstalling the trim. If he doesn’t appreciate the work that you’ve done, he obviously doesn’t understand the car appearance enthusiast. Turn around and walk out, because you’re not in the right place.
If the manager appreciates your preparation work, let him know you want to inspect the car prior to painting. This immediately tells him that you know your stuff, and that the car needs to be properly prepared before he calls you.
Your Pal, the Professional Painter
Ask to meet the painter and spend a little time getting to know that person. Let him or her know you are a fanatic about your car’s appearance. Make it clear that careful masking is important to you, including the wheel wells, underbody, engine compartment, air ducts and other inlets.
Indicate that you want no apparent sign of paintwork when the job is complete. If the painter understands what you want, you’ve found the right place. If not, turn around and head for the exit.
The Pre-Paint Inspection
When the manager calls you for a paint pre-inspection, don’t wait. Go immediately and inspect the work. If they replaced a body panel, look at the alignment. Is it straight with an even panel gap all the way around? Did they do a neat job of applying body panel cement at the mounting points? If they repaired a dented panel, can you see the repair?
Thump the area repaired. Does it sound “thick” like they applied a lot of body filler instead of pounding out the dent? Have all of the pinholes and grinding marks been filled? Be very critical. It doesn’t get better when the top coat paint is applied.
Post-Paint Inspection Period
After the painting is complete, and it’s time for you to pick up your car, inspect the work again. If they buffed the paint, look closely to be sure they didn’t leave swirl marks. Look for overspray. Look for a consistent paint finish that’s free of orange peel, fish eyes and other obvious painting defects.
When you’re satisfied, pay by credit card. If you’re not happy, review the problems with the manager. If the problems can be easily corrected, let them fix their work.
When Paint & Bodywork is Complete
If you removed trim, by the time you get your car home, the paint will be cured enough to begin reinstalling the trim. Be careful, though, as the paint is still soft and can be easily marred. If you’re reinstalling a large part, such as a bumper, do not work alone. Ask someone to help you.
During the first 30 days after the paintwork, don’t use any chemicals on the fresh paint. Wash with cool water and a good wash tool. Do not wax until the paint has cured for a full 30 days. If you wax too soon, you’ll risk discoloring the paint from trapped solvents. The solvents need to off-gas completely.
Be sure to visit our paint repair section!