You’ve seen them on the road: cars and trucks with headlight lenses that are cloudy and milky-looking. It makes a vehicle look dingy and cuts the headlights’ effectiveness.
The good news is that you don’t have to drive around with headlights that look like they have cataracts. We’re going to talk about how to clean foggy headlights and make them more effective.
What is a foggy headlight?
A foggy headlight is one where the exterior lens appears cloudy and semi-opaque, rather than clear. This happens over time as polycarbonate headlight lenses are exposed to the elements, UV rays and dust and debris from roads.
Starting in the early 1980s, the Department of Transportation rewrote regulations that allowed automakers to move on from glass sealed-beam headlights. For the first time, motorists could replace headlamp bulbs without having to change out the whole assembly.
It also allowed automakers to design vehicles with halogen headlights with European-style polycarbonate lenses. This led to some sleek headlight designs. But the downside is that without proper care, the polycarbonate lenses fog over time.
Dangers of foggy headlights
A foggy headlight will affect your visibility at night. The lenses will actually absorb some of the blue-light frequencies that your headlights project. This leaves you with a yellowish field of light. In extreme cases, that can cut as much as 80% of the candlepower your headlights are designed to project.
In addition, the cloudiness can cause light to be refracted out at angles. This makes it hazardous for other drivers. It can also cause the actual headlight element itself to overheat, which will shorten its service life.
New headlight assemblies can be expensive. They can also be difficult to replace for the average owner. If you know how to clean a headlight lens, though, this doesn’t have to be the case.
How to clean foggy headlights
If your headlights are foggy and cloudy, there’s a top layer of the lens that’s degraded. What you’ll need to do to fix those cloudy headlights is to gently remove that surface layer of plastic. This will reveal the clearer, undamaged plastic that’s below.
You’ll need a mild abrasive and some elbow grease to remove that cloudiness. The type of abrasive solution and the amount of work you have to put into it will depend on how serious the cloudiness is. Of course, before starting with any of these methods you’ll need to wash the headlight lenses thoroughly and remove any dust or road grit.
Toothpaste contains a mild abrasive in order to clean your teeth. In fact, early formulations of toothpaste contained crushed eggshells to provide grit. If your headlight lenses aren’t too far gone, you can use toothpaste on a towel to remove the cloudiness, rubbing in a circular motion like you would when polishing with a coat of wax.
Rather than acting as a physical abrasive, some of the chemicals found in insect repellant mildly degrade plastics. To restore the headlights, spray a liberal amount of bug spray on a rag and then rub and buff in a circular motion. Once you’re satisfied, clean off any leftover residue so it doesn’t continue to degrade the plastic.
Be careful to not let the spray make it onto other plastic or painted surfaces. It might be a good idea to use newspaper and masking tape to protect those other surfaces and head off the chance of any damage.
Baking soda and vinegar
Most everyone knows the grade-school chemistry of mixing baking soda and vinegar to make a foamy “volcano.” You can use them for headlights as well. Mix two or three tablespoons of baking soda with enough vinegar to form a thick paste. Apply the paste with a dry towel, then rinse it off with a spray bottle of water. You may need several applications before you see results, but it can be an effective way to fix cloudy headlights.
Car polish contains a mild abrasive. It’s what removes oxidized paint as you polish and wax your car. In some cases, this can be enough to restore headlights. In more extreme cases, you might want to use some rubbing compound as well, which is used to efface minor scrapes and blemishes in a car’s finish.
Headlight restoration kits might include compounds that need to be mixed together (there are various products on the market for this process). Be sure to follow the directions to the letter and don’t improvise. Most headlight restoration kits will require you to use a microfiber cloth. Some might allow you to use a soft buffing wheel on a drill.
As you can imagine, you’ll need to be careful with this method. Remember that you’re only trying to remove the affected layer and not go deeper into the plastic.
You’ll need a spray bottle with soapy water, a clean low-lint towel and sheets of 400-, 1,000- and 3,000-grit sandpaper. Spray down the surface with the soapy water and wipe to remove any dirt or bugs, then continue to spray a light layer of soapy water as you sand with the 400-grit sandpaper to remove the worst of the oxidized material.
From there, switch to the 1,000-grit and then the 3,000-grit paper, continually using the soapy water. By the time you’re done, the lenses are likely to look rough, scratched and even hazier. This is part of the process and completely normal.
Your next step will be to apply automotive polish to restore the shine and transparency to the surface. Finally, apply a coat of wax or clear coat to seal and preserve them.
With all these methods, patience is the key. You may need repeated applications and lots of rubbing and buffing to get the results you need. But the first time you turn on your headlights at night you’ll see that it was worth all the work.