Over time, the plastic covers on your headlights and taillights may start to look dirty. Sometimes, they even “fog” which not only looks unattractive but can also change the refraction angles of your headlights, making them less effective.
Naturally, you’ll want to fix this.
Restoring headlights can be surprisingly easy and helps keep your car from showing its age prematurely. It also helps to keep your head and tail lights, important safety features on your car, working at optimal effectiveness.
What Causes the Dinginess?
Most of the time, headlight dinginess has one of a few fairly predictable causes. The first is, obviously, dirt. You likely already know how your car came into contact with dirt and what to do about it. The next causes are more interesting.
The second most frequent cause is oxidation. When the plastic lens is exposed to UV radiation, it can develop cracks, which cause headlights to have a cloudy appearance. This can also cause the yellow-tinge you might notice.
Road damage and chemicals affect the headlights as well as the rest of your car. If you live in an area with snow where the roads are treated to reduce iciness, then that slush can set up on your headlights and cause dimming. You can also get hit by small bits of gravel that cause tiny pits and scratches on the headlight.
Water vapor sometimes gets caught in the headlight plastic as well. You’ll know right away if this is the cause of your cloudiness though, as typically it looks like a few droplets of water on the inside of the headlight first thing in the morning.
As long as you don’t have any major cracks, the process for restoring your headlights is going to be mostly the same.
Preparing Your Car
The first step for any headlight restoration is cleaning up the front of your car. Go ahead and do an exterior wash and rinse like normal and then let your car dry completely. Once dry, surround the edges of your headlight with painters tape, just like you would if you were covering windows before painting the inside of your house.
You want to use painters tape, or a similarly low-stick tape so that it won’t damage your car paint, and you want to only allow the headlight to show for roughly the same reason. Almost all of the techniques for cleaning your headlights will involve using techniques that aren’t good for the paint on the rest of your car. Covering the paint will help to keep it protected, but keep in mind that that’s your circle of protection, so you can’t venture outside of it. Also, although painters tape is great stuff, you’ll still want to be as careful as you can be. Just like with painting in a house, it’s there to give you a safety net in case you color outside of the lines a little bit, but you should still test that net as little as possible.
Now that your headlights are prepped for restoration, you’ll want to decide on what method is right for the level of discoloration that you’re dealing with.
Appraising the Damage
If your headlights are only a little bit yellowed or discolored, then you can go ahead and skip past the sanding and go straight to the polishing step.
On the other hand, if your headlights are showing substantial signs of age and oxidization, then you’ll want to do a more thorough job of removing all of the damage before polishing it up. Though starting with sanding definitely takes more time, it will definitely add a more professional touch to your completed process and will remove substantial damage.
Sandpaper for Headlight Restoration
The first step in a serious headlight restoration process is sanding. For sandpaper, the higher the grit number, the finer the sandpaper. For headlights, you’ll most likely want to start with 2000, which is substantially finer than you likely have around for most household purposes. Some people even start with a 3000 grit for their headlights. If you start with a 1500 or 2000 sandpaper, then you should also purchase the 3000 grit. You’ll start with the coarsest and then work your way to the finest grit.
Because of how fine of a grit is required to properly sand headlights, getting a headlight restoration kit is often the best idea since it includes all of the materials that you’ll want without having to hunt for sandpaper.
Most importantly, in addition to finding sandpaper with a very fine grit, you’ll also need one that can be used wet. It will likely have printed on it somewhere that it is “waterproof” or good for “wet sanding.”
In order to get the results that you want, you’ll need to keep your surface continually wet while you’re sanding. This is incredibly important as dry sanding can cause small scratches that may actually make the surface worse than it is now.
As you sand, the water may start to gain a milky quality. If that’s the case then go ahead and wipe it away with a clean microfiber cloth and then spray clean water onto the surface once again. This will keep you from rubbing more grit and debris into the surface as you’re sanding.
Some people have used a rotary tool, like a Dremel, or even a power drill with a sanding attachment for this. While it definitely decreases the amount of time spent sanding the plastic, it doesn’t substantially improve the results and can be slightly more challenging to control. There are specific detailing discs that can be used for this purpose that are finer grade and can be purchased in any automotive specialty shop. You can recreate the same results without this tool though, you’ll just be using a little more arm strength.
After sanding, even if you did a great job with the wet sanding, you’ll likely notice small sanding marks, and this is where a polishing compound will come in and finish the job up for you.
First, go ahead and spray down the headlight and clean it up again before applying the polishing compound.
If your headlights have only just started to gain that dingy quality you can start here, or you can move to polishing after finishing sanding. Either way, your steps from here will be the same.
Some people recommend using toothpaste instead of a polishing compound, and there are certainly pros and cons to both methods.
The Toothpaste Method
Toothpaste is great stuff, and in addition to keeping your teeth cavity-free, it can also serve as a cleaner and polisher for a variety of household applications. A while back, someone got the idea to try it out on headlights, and lo and behold, it worked. Sort of.
Toothpaste does a good job of gently removing road debris, salt, and other minor causes of headlight dinge. If you only are trying to get rid of the most minor of headlight dirt, then polishing with toothpaste is a definite possibility. Toothpaste is a minor abrasive, which is how it’s able to get your teeth so clean. Consequently, it can also buff away the most minor of scratches and is able to do so without taking too much off of your plastic headlights.
Toothpaste won’t do anything at all for glass though, and its capacity for buffing is incredibly limited, which means that it’s likely you’ll need to do a little more to actually get your headlights clean.
First, you’ll want to apply a general toothpaste (not whitening, charcoal activated, or full of microcrystals) and mix with water. Using a soft cloth (microfiber is great, but an old t-shirt is also okay) rub the mixture on in slow gentle circles. Repeat as often as necessary.
This is a stronger abrasive than toothpaste and produces more consistently good results. A headlight polishing compound is an inexpensive solution that applies pretty much the same way, but is able to fill in minor scratches as well.
There are many types of compounds that can be used in headlights. Though some are specifically formulated for headlights, many more are for plastic parts in general, and those will work fine as well.
The biggest difference between types of compound is how gritty they are. Grittier compounds are harsher and will be able to polish out more significant scratches, but they also file away more of the plastic that makes your headlights resistant to the weather and wear and tear.
Essentially, the best polishing compound is the least gritty one that you can get away with. You can try using a finer compound in a small area of your headlight and then rinse and dry to see how much of an effect it had. If not enough, then you can use a grittier headlight compound.
You’ll want to go ahead and set a timer for polishing compound because it’s most effective when rubbed on for several minutes at a slow and steady pace, but a few minutes sounds much shorter than it feels. A timer will also help you achieve more even results on both headlights.
With a polishing compound remember you can always add more and start with a small amount. Work that amount in small, circular motions. This is the final step, so you should be refining more than trying to sand at this stage of the process. A clean microfiber towel works best, but you can also use old t-shirts, or some people have even claimed to have great success using newsprint.
Once you’ve gotten your headlights looking clear and new, you should apply a UV protectant spray. Though your car comes from the factory with this, you’ve almost certainly removed it during your restoration, and it was likely oxidized before that. A simple coat will help to protect your good work so that you get to enjoy your freshly restored headlights for a while to come.
Restoring headlights is one of those detailing jobs that everyone feels great about when they’ve finished because it immediately gives your car a facelift that can be shown off the same day that you do it, and it doesn’t take a huge amount of time. The toughest part will be not ranting to everyone you see with dirty headlights about how easy it is.
Image Credit: Cars for Sale, Mustang Cobra SVT, Popular Mechanics, 3M