Healing Hazy Headlamps

Got plastic headlamp covers? Are they hazy or cloudy or turning yellow? Pitted and scratched? Here’s some suggestions for making your headlights look and work like new again. Try a little corner of your lens as a test patch if you are unsure whether attempting to polish your headlights will make the situation better or worse.

Clean the lens using various compounds and polishes.
 
Most auto parts stores have a kit for polishing head and taillight lenses. Brands typically found at your local auto parts or big box store include:

◊ Meguiar's PlastX
 
◊ Novus (#2 for fine scratches, #3 for polish)
 
◊ Mothers Plastic Polish
 
◊ DuPont polishing compound (white)
 
◊ Brasso (the manufacturer says it’s for polishing metal, but people often use it for polishing plastic, including CDs and DVDs as well as iPod screens).

◊ Gel fluoride toothpaste*

◊  Brake part/carb/throttle body cleaner**
 
Compound Application techniques.

Rub on just using a regular terry cloth towel. Some people just grab an old gym sock. One CarSpace member used very fine polishing compound and a soft cotton buffing pad on a drill motor. Be careful or you will put burn marks in the plastic and they are almost impossible to get out.

Whether you use a polishing compound, toothpaste, Brasso or one of the commercial plastic polishes to clear up the haze, the technique is largely the same. Just put some on a small cloth and use it as if you were using a very fine rubbing compound, turning the cloth as needed and re-wetting with the polish, then finishing with a clean, dry cloth. Repeat until any haze, scratches, and pitting disappear. These products generally are very fine abrasives, not just cleaners, so they actually grind out the scratches and pits, with a little bit of effort.

*The suggested use of fluoride toothpaste was from a boat yard repair that a CarSpace member had success with. Smear some gel fluoride toothpaste on the lenses and rub it on with your fingers and leave it on overnight. Then simply wash it off. The fluoride supposedly reacts with the acrylic  to remove the UV aged film, but maybe it’s just the abrasive nature of the toothpaste that actually does the work. Chances are you have some toothpaste handy you can try and save yourself a trip to the store.

** See Doohickey's comment and photos below for his throttle body cleaner trick - thanks Doohickey!

Buffing.

Some people use a series of fine grit sandpaper to wet sand the lenses, but that may be a bit extreme unless you can’t get satisfactory results with the polishing techniques above.

To buff out headlight lenses, it's best to remove the light assembly first. Then start with 600 or 800 grit wet/dry paper and work your way up to 1200, and finally 1500 grit. Let the paper do the work and don't use too much elbow grease. Keep a spray bottle of water handy and spritz your work frequently. Then polish as above. The lens won't exactly look new but you can easily make a huge improvement with the investment of a few hours of your time and a few bucks worth of supplies.

Repair of cracks.

A polycarbonate adhesive has been used to repair cracks in lens by CarSpace forum member Caribou1. His recommended brand, Makrolon Adhesive, may be hard to find in the US, but there are US sources on the internet. A resin adhesive made for laminating Lexan should also work. This adhesive is used to assemble aquariums, so you may find some suitable glue at your local aquarium store. Once the adhesive dries, you can polish any excess off using the cleaning tips here.

Replacement.

If none of these suggestions work (or you get a bit overzealous with buffing and sanding), you can get a new lens or light unit. They are readily available from your dealer and on eBay. Usually the lens are easy to change. You can also find replacements at the local salvage yard but if you are trying to replace older yellowed lens, the old ones in the salvage  yards may be hazy too just from the passage of time and long exposure to the sun and elements.

Prevention.

Polycarbonate headlamp lenses are sensitive. Avoid putting chemicals on them - GM recommends avoiding rubbing compound, grease and tar removers, tire cleaners, cleaner waxes, chemicals used to remove rail dust and even some car wash soaps in too high a concentration.

Precut plastic headlight covers will take the brunt of the road debris and may prevent any hazing and yellowing. Some covers stick out a bit from the lens and attach mechanically or you can get the thin plastic  protective film that 3M and other companies make and cut it to fit over the lens. The film is virtually invisible.Griotsgarage.com is one supplier.

After polishing plastic headlights, some CarSpace members have found that the lens often haze over much quicker than they did originally. This is reportedly because the manufacturer coats the lens with a protective layer. Polishing will remove this protective layer.

Some of the headlight polishing kits have a final coating you put on after polishing. Or you can use a product like 303 Aerospace Protectant or paste wax. This treatment may help the repair last longer.

Use the leftover plastic polish for polishing your iPod Nano screen, your watch crystal (ok, your cell phone screen) or your acrylic hot tub.

There's a recent Edmunds article with good pics at the Used Car Corner: Restoring Your Headlights (Wax on, Wax off)

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