Your headlights are as essential for safe driving as good brakes and working seatbelts. You can easily replace or upgrade your lightbulbs, but if your headlight casing is yellowed, fogged or cracked it’s going to take a bit more to get them back to their best.
Why You Need to Keep your Headlights Clean
Cars used to have glass headlights that kept their shine for years with minimal maintenance, but over the years a lot of parts have changed to plastic and headlight casings are no different. They’re cheaper for car manufacturers to make, strong enough to hold up against modern motoring, and can be moulded into almost any shape imaginable.
How Headlights are Made
Plastic, or more specifically, polycarbonate headlights are strong, versatile and easy to mass produce. They can be injection moulded into just about any shape imaginable, which is why modern cars have such a wide range of headlight shapes and sizes.
Once the headlight casings have been moulded, they’re sprayed with a clear protective coating. It’s this coating that keeps the headlight from getting chipped, scratched or oxidised over time.
How Headlights Deteriorate
The downside of plastic headlight casings though is that they deteriorate much faster than their glass counterparts. UV ray damage from sunlight has a serious ageing effect on the polycarbonate used in their construction.
Keeping your headlights clean is the best way to slow down the oxidisation process that leads to milky headlights.
Preparing Damaged Headlights for Restoring
There are a few different ways to go about restoring your headlights if they’re really damaged. You can buy a kit that contains everything you need or do it fully DIY if you have a decent set of tools. As with any job done well, proper preparation is key to the best finish.
In order to prepare your headlights properly, you have to think about what’s happened to the polycarbonate surface up close. When the protective coating has been exposed to UV rays and scratches, it bubbles up and chips off.
These tiny blemishes must be rubbed off before you can replace the protective layer, so make sure you get hold of the best sandpaper available for the job. Not all sandpaper is made equally, the cheap stuff gets clogged up and won’t cut through the damaged layer on your headlights.
You shouldn’t ever dry sand your headlights, so make sure you get hold of wet & dry sandpaper before you attack the oxidised layer. For the best results, use a spray bottle filled with water to keep the headlight and paper wet throughout.
If you can, remove your headlights. Working on them on your bench is much easier, but plenty of headlights are too difficult to remove to be practical. If this is the case, you can use wide painter’s tape to protect the paintwork around your headlights.
Start with a lower 800 grit sandpaper and rub in a circular motion using a light, but even pressure. If you have a drill and a backing pad attachment, you’ll save yourself a lot of arm-ache here. Start off on a low speed and increase the power slowly, making sure the surface is kept wet. Overlap your sanding to keep things even.
Wipe the surface with a microfibre cloth afterwards and change to a higher 1200 grit sandpaper. Repeat the wet sanding process across the headlights, and then change up to a super fine 3000 grit sandpaper. This will remove any trace of the old coating and you’re ready to re-coat your headlight.
Once you’ve sanded the headlight, use isopropyl alcohol to clean the surface of any remaining dust or grit that could affect the next stage of the repair.
Re-Coating Your Headlights
Now you’ve removed the old protective coating from your damaged headlights, you can completely restore them by re-coating with protective spray. If you’ve opted for a kit to restore your headlights, there will be a wipe-on liquid, but you can get decent results from other products as well.
Although you can use regular clear coat lacquer spray, it’s not that durable and could result in you having to re-do the job on your headlights again. We suggest using a proper car headlight protectant, they’re a bit more expensive but are designed to protect against the punishment that headlights receive.
Follow the instructions on the packaging, but you should always try to apply any protective liquid or spray as evenly as possible and remember that multiple light coats are much more effective than one thick one. Most protective coats will cur quickly in direct sunlight but take much longer in damp or humid conditions.
Cleaning Products to Use on Your Headlights
If your headlights aren’t completely worn out or damaged, you can spruce them up with a good clean. There are specific headlight cleaning products out there, but you probably have a few at home already. Here are our favourites:
- WD-40 is a magic all-purpose cleaner and de-greaser that works wonders on your headlights, if only for a quick fix. Wipe it on with a paper towel and restore your headlights temporarily
- Toothpaste isn’t just for your teeth because it can work wonders on lightly damaged car headlights. Make sure it contains baking soda or another mild abrasive, and rub it on with a cloth or even an old toothbrush
- Baking soda is widely available and works as a mild abrasive cleaner that you can use on different surfaces to bring them back to life. Make a thick paste with a little water and rub it on your headlight with a nylon brush
Headlight Cleaning Techniques
Finding the right cleaning product for your headlights is only half of the battle. There’s no point finding the best material to use if you can’t get the most out of it. Whether you’re using elbow grease or a hand drill, the devil’s in the detail:
Alternate your sanding pattern when restoring headlights. Start with a circular motion when using coarser grits to remove the most material. Switch to a horizontal pattern when you get to the finer grits as this creates micro grooves in the surface that will help the protective coat to stick on.
Don’t forget to always use wet & dry sandpaper, and keep both sandpaper and headlight wet with a spray bottle while you’re working on it. Trying to sand back foggy headlights dry will end in a worse finish than before.
Maintaining Your Headlights
Prevention is always more effective than cure, so the best way to keep your headlights looking bright is to prevent them from getting fogged in the first place. Regularly cleaning your headlights with warm, soapy water or a quality car shampoo will keep them from getting grimy.
You should keep an eye out for the first signs of yellowing or fogging, rather than wait for your headlights to get so bad that you need to resort to sandpaper and clear coat. A regular polish up with WD-40 or even toothpaste will save you time and effort in the long run.