Cleaning and Renewing Yellowed Automobile Headlight Lens Covers

Are your car's light covers yellowed, cloudy or scratched? You're not the only one. Unless you provide your car's clear headlamp lenses regular attention, in 24 months or less they can deteriorate to the point of being completely opaque, making it very hazardous to operate your automobile in the dark and in reduced visibility conditions. The fix is easier than you might think. The best thing is that you can remedy this hazardous and ugly issue in thirty minutes or less. It's simple once you learn how.

The Reason Headlights Turn Yellow and Dull?

The issue is not caused by abuse or neglect, as you might think. It is an environmental issue. Without regular maintenance, UV light from the sun, acid rain, salt and road debris damage and dull all clear plastics, including headlight covers. If your car has halogen or another type of high-intensity discharge (HID) headlights, the issue can be worse. These sealed beam units function at increased temperatures, further contributing to degradation and yellowing.

How Do You Fix The Problem?

The solution is a quick car detailing task that renews the finish. Headlamp restoration is a plastic restoration process that removes surface damage and returns a like-new finish to the lenses. Even hopeless-looking cases of yellowing, hazing, and scratches can be fixed in less than a half hour.

You might be asking yourself why repair instead of replace? Your headlamps are a single module, so you can't easily replace the outer cover. If you have an expensive car with high-performance lighting, replacement is expensive. Renewing versus replacement can save you $150 to $600 per lens, so it's well worth the effort. Besides, it's easy!

What level results can you expect? It may seem hopeless, but chances are the damage is superficial. Even if your headlights are completely opaque, they can be renewed. As long as the plastic has not yellowed all the way though, you have a very good chance of complete restoration.

Use A Gentle Plastic Polish First

If the damage is not severe, you may be able to resolve it with a simple plastic polish like Meguiar's PlastX. I recommend trying this solution before any other. It will not be wasted time or cost, either, because you should use the polish from time-to-time to maintain your lighting.

NOTE: Never use a household glass cleaning product like Windex on clear plastic. These cleaners contain ammonia, which causes clear plastic to yellow.

If the polish alone does not work, then you need to repair the damage with a very fine sand paper (2000 grit is very safe) and re-polish to restore a clear finish. While it may sound difficult or complicated, it's not. Wet sanding is fast and easy.

TIP: You can test to see if your headlamps will respond to hand polishing with a small dab of tartar control toothpaste. Toothpaste is slightly abrasive. If the small test area vastly improves, then you know polish alone may be all you require.

Sandpaper & Re-glazing Procedure

To restore the damage with wet sanding and re-glazing, you require the following supplies:

1. Polishing towels


2. Bucket of soapy water


3. Latex gloves (if you have sensitive skin)


4. Painter's masking tape (1" to 1.5" width is best)


5. Plastic polish


6. Wet/dry sand paper (600, 1200, 2000 grit)


7. Sanding block (1" x 2" erasure works great)


8. 2.5" Velcro backing plate for use with 3/8" drill or cordless drill


9. 3" foam or wool polishing pad with Velcro backing

If you require a more in-depth guide, then have a look at my Guide to Detailing page on Restoring Plastic Headlight Lenses. Here's the procedure:

1: Clean the car light lenses. A bucket of soapy water works best. Clean the surrounding area, too. Dry thoroughly.

2: Use painter's masking tape to mask around the headlight. This will help protect your car's paint finish. This only takes a few minutes, so don't skip this critical step.

3: Wet sand each headlight. First determine the amount of damage to each lens. If your headlight lenses are scratched or if they are completely opaque, you will need to start with 600 grit sandpaper. Sand thoroughly, and then progress to1200, then 2000 grit.

If your lenses have no scratches and are only slightly yellowed, you can probably get away with using 2000 grit paper only. The first sanding step is where you will actually remove the scratched and cloudy layer of plastic. The finer grades of sandpaper are to remove the scratches left from the previous grit sandpaper.

As you sand, your sanding water will turn milky. This is the damaged layer being removed. Use plenty of water for lubrication and to keep the sandpaper clean. Keep sanding until the surface feels perfectly smooth. The drippings will become clearer as the damage is taken away. Dry thoroughly between sanding steps to inspect progress.

4: Re-glaze headlight lenses using plastic polish on a 3" polishing pad (foam or wool). First connect the Velcro backing plate adapter to your drill.

Apply several dabs of polish to the pad and start polishing the lens. As the polish starts to dissipate, add a bit more and continue polishing. Discontinue polishing at the point the lens is completely clear again. Finish with a final hand polish using a tiny bit of polish on a clean towel or applicator.

5: Wax to protect. Use a good car wax to reseal the plastic and protect from the elements.

6: Maintain monthly with a quality plastic cleaner/polish. The products I recommend most are Plexus and Meguiar's PlastX. If polished regularly, your car's headlight lenses will never need restoring again!

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