Headlight Clear Coat Damage Reduces Light Output
Cars and trucks with dull, cloudy, yellowed headlights: you see them all the time, on vehicles on the road, in parking lots, and maybe in your own driveway. Because of damaged headlight clear coat, the headlights don't put out as much light as they used to. They look bad, they make the vehicle look aged, and there's nothing good about them except for the replacement headlamp sales they generate.
The headlamps in question are made from polycarbonate plastic (PC). During the 1980s, most car and truck manufacturers stopped producing headlights with glass and began using polycarbonate plastic because it's lightweight and can easily be formed into complex shapes for many different vehicle designs. Polycarbonate has the benefit of not breaking as easily as glass, but the downside is the dullness, cloudiness, and yellowing that occurs as the headlamp ages.
Consequences of Dull, Cloudy, Yellowed Headlights
Appearance of headlamps is a cosmetic thing; the more important issue is safety. Drivers cannot afford any reduction in visibility. Consider that 50 percent of vehicle collisions occur at night, and according to the Automotive Aftermarket Industry Association (AAIA), 26 percent of these collisions were caused by poor lighting.
The Numbers on Light Loss
Research from the American Automobile Association (AAA) found that dull, cloudy, yellowed headlights on low beam show a reduction in light output of nearly 80 percent compared to when they were new. In other words, deteriorated headlights may produce only about 22 percent of the light of new ones, making the road, other cars, pedestrians, and deer roughly 80 percent less visible at night.
AAA reached these conclusions using an accredited laboratory to test headlights from two popular sedans that had been in service for about 11 years. Light output from the deteriorated headlights was compared against corresponding new headlights to quantify the reduction, with all testing done in accordance with Federal Motor Vehicle Safety Standard 108.
There are other consequences beyond the safety issue. Diminished headlamps carry a chance of a fix-it ticket and fine from local police, and a vehicle's resale value can be negatively affected by poor headlight appearance.
What Causes Headlight Clear Coat to Fail
So what causes polycarbonate plastic headlamps to deteriorate? There are several factors:
| UV exposure | Sunlight breaks down the factory headlight clear coat, causing yellowing and clouding. UV rays can also cause the lens to develop micro-cracks, which speeds up the color change and diminishes light output. |
| Road debris | Gravel, road salt, and other debris striking the headlamps wear down the clear coat and create pits and scratches that add to the cloudy appearance. |
| Acid rain | Chemical pollutants in the air react with water vapor and oxidants to form sulfuric and nitric acids, which fall out during rain or snow and etch the lenses, adding to cloudiness. |
| Heat and porosity | Polycarbonate lenses are porous, and heat from the bulb and the sun causes them to absorb dust and debris particles through these tiny pores, which refract light and create glare for oncoming drivers. |
All of this contributes to dull, cloudy, yellowed lenses. In some cases, headlights can require maintenance within just three to five years of use.
Can Headlight Damage Be Avoided?
There are ways to mitigate damage to polycarbonate plastic headlamps. Avoiding UV exposure is at the top of the list: park your car in a garage, or at least in the shade, and face the car away from the sun when parking outdoors to reduce UV exposure. Keeping your headlights clean from dirt and chemicals matters too. Wash them at least every three months with car wash soap and a sponge, and remove early signs of yellowing by carefully polishing the headlights with a non-abrasive polishing medium and a microfiber cloth.
Can Polycarbonate Headlights Be Restored?
If the polycarbonate headlamps aren't too badly damaged, there are options for economically restoring them rather than installing new units. A replacement headlamp typically ranges from $130 to $430 depending on whether it's an OEM or aftermarket part.
Restoration starts by removing the oxidized outer layer where pits, cloudiness, and yellowing reside. This is typically done with a fine abrasive, like fine sandpaper or an abrasive pad, until the damage is removed. In extreme cases, a heavier abrasive is needed, followed by polishing with a compound to smooth the surface.
Once a headlamp is restored, the lens surface needs to be sealed with a high-performance headlight clear coat, or it will cloud over again in short order. This new protective coating replaces the failed factory coating, so it needs to be UV stable enough to handle sunlight without yellowing, along with durable and flexible enough to handle impact from gravel and debris without chipping, cracking, or peeling.
Headlight restoration is far more cost effective than headlight replacement, and both professional restoration services and do-it-yourself kits are available.
The KBS Coatings Headlight Restore Kit
The KBS Coatings Headlight Restore Kit has everything needed to restore 4 or more polycarbonate plastic headlight lenses, at a fraction of the typical $130 to $430 cost of replacement headlights.
Included in the Headlight Restore Kit is KBS Klean, used along with the included scrub pad to clean the surface and remove oxidation, cloudiness, and yellowing. KBS Klean is a powerful, concentrated, water-based cleaner that deeply penetrates and cleans surfaces without leaving harmful residues or emitting noxious fumes. This procedure properly prepares the surface for applying KBS Coatings DiamondFinish Clear.
DiamondFinish Clear is a moisture cured, crystal clear, one-part urethane clear coat that's UV stable, durable, and extremely tough. It performs in the toughest environments without yellowing, cracking, or peeling. Because of its Advanced Cross-Linked Coatings Technology, it performs extremely well as a headlight clear coat, staying flexible and durable enough to resist chips and cracks without delaminating or flaking away from the surface. For a demonstration of DiamondFinish Clear's flexibility and durability, see this video.
DiamondFinish Clear is a single component (1K) coating, meaning no self-mixing of two parts, and it's applied with the included sponge brushes. Since the coating is self-leveling, it leaves a beautifully smooth surface without brush marks, something most headlight clear coats struggle with.
Check out the demonstration below of the Headlight Restore Kit in action.
Dull, cloudy, yellowed headlights affect both the safety and appearance of vehicles. It's important to maintain polycarbonate plastic headlights to keep light output as close to original as possible and to keep the headlights looking clear and bright.
Frequently Asked Questions
Why do headlights turn yellow and cloudy over time?
Modern headlights are made of polycarbonate plastic coated with a protective clear coat. UV exposure breaks down that clear coat over time, causing yellowing, clouding, and micro-cracks. Gravel, road salt, debris, and acid rain add further wear, pitting and scratching the surface.
How much light output do cloudy headlights actually lose?
Research from the American Automobile Association found that dull, cloudy, yellowed headlights on low beam can lose nearly 80 percent of their light output compared to new headlights, meaning deteriorated headlights may produce only about 22 percent as much light.
Is it cheaper to restore headlights than to replace them?
Yes. Replacement headlamps typically cost $130 to $430 depending on whether it's an OEM or aftermarket part, while a headlight restoration kit costs a fraction of that and can restore 4 or more lenses.
What's included in the KBS Headlight Restore Kit?
The kit includes KBS Klean, DiamondFinish Clear, black nitrile gloves, two application brushes, a scuff pad, a stir stick, and complete instructions, enough to restore 4 or more headlight lenses.