Will Original Factory Headlights Turn Yellow After Polishing?
4 Answers
Polishing car headlights can have certain effects, as it removes the protective layer on the surface of the headlights. Therefore, waxing is usually applied after polishing. However, the wax composition on the lamp surface tends to wear off quickly. Once the wax is gone, the headlight surface oxidizes rapidly without the protective layer, leading to a decrease in light transmittance. As a result, repeated polishing becomes necessary. Excessive polishing can make the headlight cover thinner and more prone to cracking. Relevant information about car lights is as follows: 1. Introduction: Car lights refer to the lamps on vehicles, serving as tools for road illumination during night driving and as signals for various vehicle movements. 2. Reverse Light: The reverse light automatically turns on when the driver shifts into reverse gear. It is a white, transparent light primarily used to alert vehicles behind that the car is reversing.
I've been repairing cars for so many years and have seen many car owners come in to polish their factory headlights. To be honest, polishing can indeed restore clarity, but that doesn't mean it's a permanent solution. Factory headlight covers are made of special plastic, and prolonged exposure to the sun combined with scratches from road debris will eventually cause the surface to oxidize and turn yellow. Polishing is like exfoliating the headlight cover—it removes the outermost oxidized yellow layer, but the underlying material will continue to age. Here's the key: after polishing, you must apply a UV protective coating, just like putting sunscreen on your skin. Without this protection, the headlights will turn yellow again within three months. Some car owners try to save money by going to cheap roadside shops for a quick polish and leave without the coating, only to find their headlights yellower than my grandpa's reading glasses in less than half a year. Oh, and don't polish too frequently—the more you polish, the thinner the headlight cover becomes, making it even more prone to oxidation.
Last time I had the headlights of my family's old car polished, the effect right after was truly amazing—it looked like brand new headlights. It's been almost a year now, and while they haven't yellowed as quickly as before, there are still some signs of yellowing at the edges. I asked my regular auto repair technician, and he said the key is whether protective treatment was done after polishing. The original headlight covers come with an anti-UV coating, which wears off over time, causing them to yellow. Polishing removes the yellowed layer but also grinds away any remaining protective coating. Now, I use UV-protection spray to maintain the headlight covers every quarter, and I wipe off mud and water immediately after driving in the rain. The yellowing has slowed down significantly. If you only polish without maintenance, they’d probably yellow again within half a year.
Whether the factory headlights will turn yellow again after polishing largely depends on subsequent maintenance. Last time at a car detailing shop, I witnessed a case where the polished headlights were dazzlingly bright, but the owner returned after six months with lamp covers yellower than before polishing. The shop owner explained that polishing is merely an emergency treatment, equivalent to shaving off a layer of the lamp cover to expose new plastic. However, UV rays accelerate oxidation on the newly exposed plastic. Their shop now applies three layers of crystal coating plus a ceramic coating after polishing, which can prevent yellowing for up to two years. The worst scenario is cars parked outdoors; exposure to sunlight along with tree sap and bird droppings can cause visible yellowing within two weeks if no protection is applied after polishing.
