By Steve Temple, automedia.com
Today's two-part urethane paints consist of a clear coat on top of the color coat. While this system preserves the color by protecting against UV rays and provides a brighter shine, it can also get scratched fairly easily. Just rubbing your rag on a dusty surface, or having grit in the cloth itself, can leave fine lines and swirls.
Visible lines
If polishing and waxing isn't producing the smooth finish you'd like to see on your vehicle, but you can't feel the scratches with your fingernail, then a simple liquid scratch remover might do the trick. Note, however, that not all car scratches are the same. Some marks may be due to rubbing against a bumper from a car or shopping cart. The material coming into contact with your finish might be softer, and simply leaving behind a bit of material on top of the paint.
If that's the case, it may come off easily with a spray for removing tar, bugs and adhesives. Be sure to use a product specifically designed for marks on paint, as acetone or types of solvents might damage the paint. If the mark is still there after using the spray cleaner, try using a soft-grade rubbing compound (it's easy to penetrate the clear coat, so don't overdo it). You'll need to use a polishing compound to remove any fine scratches left by the rubbing compound, and then finish the job by sealing the surface with a good car wax.
Medium-depth scratches that you can feel with your fingernail require a more aggressive method of repair than simply using rubbing and polishing compounds. Bad scratches that penetrate to the color coat can require touch-up paint and possibly professional care.
Smooth operator
For the medium-depth scratches, use a car scratch remover kit. The system is fairly easy to use, requiring three separate steps and a common household drill. As with the rubbing compound mentioned above, less is more. The idea is to take off a very thin layer of the clear coat, but still leave enough on to protect the paint. And you'll need to protect the finish with a good wax or synthetic polish to bring back the shine.
Scratch removal tips
- If buffing, polishing or using a rubbing compound doesn't get scratches out, a more intensive approach could work, especially if the scratches don't penetrate to the color coat. Evaluate the depth of the scratch by running your fingernail over it. If you can feel the scratch but your fingernail doesn't catch, you can probably repair the damage.
- After washing the damaged area with soap and water, spray water on both the finish and the abrasive pad.
- Even though a 3,000-grit pad can feel soft, still only rub gently on the scratch until a bit of foam appears. After about 10 seconds of rubbing, wipe off the slurry with a wet paper towel to see if the scratch has disappeared. Don't overdo it, as the clear coat is not thick.
- The area being rubbed will dull slightly, depending on the angle of the light. The following steps will eliminate this discoloration.
- Insert the buffing wheel into a standard household drill. Note: A variable-speed trigger makes it easier to control the speed of the buffing wheel, as it's important not to let it heat up.
- To prevent splattering, smear the compound around by hand before starting the drill.
- Apply only light to medium pressure (enough to slightly compress the pad at a flat angle), operating the drill at slow to moderate speeds. Overlap the area slightly until the compound begins to dry, applying progressively lighter pressure.
- Remove any residue with a clean, dry microfiber towel. Make sure there's no dirt on your towels, or you'll just make things worse.
- Switch out the pads (they can be rinsed for reuse) and apply the remover to a clean pad. Scratch remover is typically thinner than the compound, so use care when squeezing it out or you'll have too much on the pad.
- Again, first smear the liquid without turning on the drill to minimize splatter.
- Using a light speed setting, polish the compounded area, overlapping it slightly.
- Buff the area with another clean microfiber towel until the finish matches the surrounding paint. Look at the area from various angles to ensure that all the scratches and compound have been removed. Repeat the previous step if needed. Protect with a polish or wax as a final step.
Source:
https://mobiloil.com/en/article/car-maintenance/basic-car-maintenance-tips/car-scratch-removal?stat=318514&socialnet=preview