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How to clean hazy headlights

Practical Motoring logo Practical Motoring 02-11-2016 Paul Murrell

If your headlights are misty, hazy or yellowed, they aren’t performing as well as they should. Follow our 5 steps and bring them back to sparkling form in just 30min.

© Provided by Practical Motoring

IT'S A COMMON COMPLAINT with headlights in modern cars. In 24 months, sometimes less, they can degenerate until they are almost opaque. And headlights working at less than their best make driving at night or in reduced visibility conditions dangerous.

Lens covers become discoloured not through abuse or neglect but as a natural result of being exposed to UV and the constant assault of road debris. Halogen and other types of HID (high intensity discharge) lights operate at high temperatures, so the problem can be even worse.

But in less than 30 minutes, most discoloured, hazy lens covers can be restored unless they have yellowed all the way through. Even severe cases should take no longer than 30 minutes. In most cases, the damage looks worse than it is, often being little more than superficial. Because modern lights are a fixed unit, it isn’t possible to simply replace the outer cover, and complete replacement of the unit can be horrendously expensive.

If the damage isn’t severe, you may be able to fix the problem with a low abrasive plastic polish, available from most auto accessory shops. Even if it doesn’t work, the polish will come in handy to maintain your headlight covers once you have restored them, so it won’t be money wasted. One way to see if your lenses will respond to a plastic polish is to test a small area with toothpaste, which is slightly abrasive (that’s why your dentist tells you not to use too much). If the test area responds to the toothpaste test, plastic polish may be all you need.

If the plastic polish doesn’t do the job, your next option is to remove the damage with very fine sandpaper (2000 grit is very safe to use) and while sanding back your lenses sounds scary, you’ll find wet and dry sanding is neither complicated nor challenging. You’ll need polishing towels, a bucket of soapy water, masking tape 1-1.5-inches (2.5-4cm) wide, plastic polish, wet-and-dry sandpaper in 600, 1200 and 2000 grit grades, a sanding block (cork is best, and the smaller the better), a 6cm Velcro backing plate for use with a 3/8” or cordless drill and a 5cm foam or wool polishing pad with Velcro backing.

Step 1: Clean the headlights lenses and the surrounding area. Dry thoroughly.

Step 2: Using the masking tape, carefully mask around the headlight to protect the surrounding paintwork. Take your time.

Step 3: Determine the level of damage to each headlight. If the lenses are scratched or completely opaque, you’ll need to start with 600 grit sandpaper. Major abrasions or very deep scratches may be signs of more serious issues and warrant a professional inspection. Wet sand each headlight thoroughly, using a spray bottle of water to keep the sandpaper lubricated, until you have achieved an even, dull finish, then repeat the process with 1200 grit sandpaper and finally 2000 grit. If the scratching is minimal and the lenses are only slightly opaque, you may be able to start with 2000 grit. The first sand actually removes the scratched and cloudy layer on the surface of the plastic. The finer grades of sandpaper polish out the scratches left by the previous grade. Continue the process until the lens surface has a satin finish.

You’ll notice your sanding water turning milky – this is the damaged layer being removed. Use plenty of water for lubrication and to keep the sandpaper clean. Continue the sanding process until the surface of the lens feels completely smooth under your fingers. You’ll also notice the water becoming clearer as the damage is removed. Dry thoroughly between each sanding step so you can check your progress.

Step 4: Now it’s time to re-glaze your headlight lenses using plastic polish (aluminium polishing compounds are a good bet) on a 5cm polishing pad of foam or wool. Connect the Velcro backing plate adaptor to your drill then attach the polishing pad. Apply several dabs of polish to the pad and begin polishing the lens starting at low revs and applying gentle pressure. As the polish is used up, add a little more and keep polishing. When the lens appears completely clear, finish off with a final hand polish using a small amount of plastic polish on a microfiber towel or applicator.

Step 5: Use a good quality car wax to seal and protect your newly restored lenses.

Maintenance: Each month use a quality plastic cleaner/polish to keep your lenses like new. This will ensure you never have to restore them again.

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