Car scratches can be incredibly frustrating. Tiny flaws are expensive to have fixed professionally, but it's also hard to ignore them.
The Scratched Body
Paint scratches, no matter how small, can be expensive eyesores.
You don’t need fancy tools to distinguish a scratch from a mark. A fingernail drawn over the surface at 90 degrees to the defect will tell you if it’s gouged into the paint or sitting on top of it. If it’s a mark that appears to be from rubber, plastic or even other paint, it may come off easily with an aerosol tar or adhesive remover. Stubborn marks often can be removed with acetone or lacquer thinner on a soft rag. If the mark is still there after using one of these solvents, try hand rubbing or polishing compound. First, clean the area with soap and water, then spread rubbing compound on the mark and rub the area in a circular motion until the mark disappears. Once it’s gone, switch to a back-and-forth motion to remove circular buffing marks. Buff the area with a clean cloth to remove rubbing compound. Then, using a fresh pad, clean the area with polishing compound to remove the fine scratches left by the rubbing compound. Finish by sealing the surface with a good car wax.
If the defect is a scratch, determine if it extends below the surface of the paint and into the primer. Sometimes one end of the scratch looks fine but the other end gets deeper and deeper until it breaks through into the primer and the metal underneath. How much of that scratch is below the color? If it’s a small portion of the entire scratch, you may want to repair what you can, and just try to ignore the rest until you’re prepared to repaint the panel.
Modern cars are almost always clearcoated over the color layer of the paint. This is done to provide a shinier finish, as well as to prevent ultraviolet light from fading the pigment underneath it.
Scratches in clearcoat can similarly be sanded out. However, if you sand completely through the clear into the color underneath, you have to respray the clear on that panel. That’s still easier than trying to match the color of the original paint, spraying the panel and then clearcoating over it. If the scratch goes into the primer, you’ll be forced do exactly that.
The Bumper Scuff
Bumper scuffs and scratches can't be remedied like scratches marring your paint job–this common scratch requires a bit more work. Here's how to make a scratched bumper look like new.
If there's a post in a parking lot--any post--it should be high enough to see when you're backing up. Unfortunately, the law we usually see applied is Murphy's, and the resulting body-damage repairs will cost just a few dollars less than your insurance deductible.
Foggy Headlights
After a few years, headlights don't have to be scratched to look scuffed and foggy. "Polycarbonate has a tendency to get hazy," says Popular Mechanics senior auto editor Mike Allen. "Severely neglected lenses can actually pit and develop a network of fine cracks, called craze, which makes the job of fixing them tougher." But this common malady can be fixed. We have step-by-step illustrated instructions for making your headlights look clean and clear.
Wash your car to remove any surface dirt. Waxing it, at least within a foot or two of the headlamps, is a good idea, because drips and droplets of the abrasive polishing compound are less likely to adhere to a freshly waxed surface.
Head out to the store and buy some blue, low-tack painter’s masking tape, the handy stuff that peels off easily. Mask the area around the headlamp that needs to be polished. For some reason, the red, yellow and clear lenses for the marker and backup lights, which are molded of ABS plastic, don’t seem to craze as much as polycarbonate headlamps, so you can probably just mask them as well. You may want to remove nearby trim, especially chromed metal or chrome-finish plastic, because we’ll be polishing and sanding with materials that can destroy the chrome.
That gray stuff is composed of hard-water minerals, road film and wax built up on the surface of the molded plastic panels. If the plastic is black or gray, it's black (or gray) all the way through. Beware if the plastic is the color of the body, silver or champagne, because that's painted over the base color of the plastic, and the advice I'm going to give you may not work—and may damage any paint. Treat painted areas like the rest of the car's finish.
Start by washing the area—by hand—with any commercial car-washing product as per the directions on the bottle. Use a moderately soft bristle brush to scrub any accumulated material out of the cladding's texture. Don't scratch the paint nearby. If the cladding is still blotchy when dry, try a soft cloth and straight, undiluted white vinegar. This should dissolve any minerals left behind on the surface. Rinse well.
Still blotchy? Maybe it's waxy buildup. Try a cleaner intended for vinyl surfaces, bug and tar remover or lacquer thinner on a soft cloth. Avoid getting lacquer thinner on any painted surfaces—if your car has a lacquer-based paint, the thinner will remove it.
Repainting and Bodywork
We had already sprayed the unibody inside and out with Dupont 615S self-etching primer to protect it from surface rust. Running our Campbell-Hausfeld dual-action sander lightly over the surfaces, using 100-grit paper, instantly showed high and low spots.
The next step was to sand the bad spots down to bare metal, then fill them with body filler. We mixed only a small amount at a time and threw the remains away, bowl and all. Throwing everything away avoids contaminating the next batch of filler with residue from the previous batch.
Auto body men call filler "cheese," because it is greenish-yellow and the proper time to start working it is just after the catalyst has kicked off and the filler has the consistency of Swiss cheese.
I started the sanding process by using an English File sold by The Eastwood Co. This is a body file with a turnbuckle that adjusts it to either concave or convex surfaces. It's perfect for rapidly cutting down filler.
Some auto body men like to slather large areas with filler, then sculpt it back to shape. We preferred to build up dents a small amount at a time. The sequence that worked for us is English File, DA sander with 100-grit paper, DA sander with 220-grit paper, then hand sanding with 220-grit paper wrapped around a sanding block.
The most precise tool for discovering and measuring imperfections is still the human finger. Running your hand over the surface will detect bumps and hollows you can't see.
The most difficult areas on our Camaro were the weld seams where the quarter panels meet the rear deck, and the top edge of the quarter panels where they meet the top molding. The weld seams in the door openings, floor and trunk were not filled at the factory. We brought them up to a reasonable appearance, then brushed them with seam sealer to duplicate the factory look.
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