Cleaning and Restoring Yellowed Automobile Headlight Lenses

Are your automobile's headlamps yellowed, cloudy or scratched? You're not the only one. Unless you provide your vehicle's plastic headlamp lenses regular care, in two years or less they can cloud to the point of being completely opaque, making it very unsafe to drive your car in the dark and in reduced visibility conditions. The fix is easier than you might think. The good thing is that you can remedy this hazardous and ugly problem in about 20 minutes. It's simple once you understand how.

The Reason Headlights Turn Yellow and Dull?

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

What Is The Solution?

The cure is a quick restoration process. Headlamp restoration is a plastic restoration process that does away with visible damage and restores clarity to the lenses. Even bad cases of yellowing, hazing, and scratches can be fixed in less than 30 minutes.

You might be wondering why restore instead of replace? Your headlamps are a single module, so you can't simply replace the lens cover. If you have an expensive car with high-performance lighting, replacement is very expensive. Renewing versus replacement can save you hundreds of dollars per lens, so it's well worth the energy. Plus, it's so simple!

What kind of results can you achieve? It may look hopeless, but chances are the damage is superficial. Even if your lenses are totally opaque, they can be fixed. As long as the plastic has not yellowed all the way though, you stand a very good chance of full restoration.

Try A Low Abrasive Plastic Polish First

If the damage is slight, you might be able to fix it with a basic plastic polish from the auto parts store. I suggest trying this method first. It will not be wasted effort or cost, either, because you should use the polish regularly to maintain your lighting.

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

If the polish by it self does not do the job, then you need to remove the damage with a very fine sand paper (2000 grit is very safe) and re-glaze to restore a clear finish. While it may seem difficult or complicated, it's not. Wet sanding is quick and simple.

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

Wet Sanding & Re-polishing Process

To remove the damage with wet sanding and re-glazing, you need the following basics:

Polishing towels

Bucket of soapy water

Latex gloves (if you have sensitive skin)

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

Plastic polish

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

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

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

3" foam or wool polishing pad with Velcro backing

If you need a pictorial guide, then have a look at my Guide to Detailing blog. Here are the steps:

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

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

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

If your lenses have no scratches and are only slightly cloudy, 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 cleaned away. Use plenty of water for lubrication and to keep the sandpaper clean. Continue sanding until the surface feels perfectly smooth. The drippings will become clearer as the damage is taken away. Dry thoroughly between sanding steps to check progress.

STEP 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 a small amount of polish to the pad and start polishing the plastic. As the polish begins to dissipate, add a bit more and continue polishing. Stop polishing once the lens is perfectly clear again. Finish with a final hand rub using a tiny bit of polish on a clean towel or applicator.

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

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