Cloudy headlights are not dirt. They are sun-damaged plastic, and the fix only holds if you understand what is actually happening to the lens.
If you have ever pulled up behind a ten-year-old car at a stoplight and noticed its headlights look like they are wearing a thin layer of frosted glass, you have seen the most common and most misunderstood problem in car care. People assume it is dirt, or old age, or a coating wearing off the outside. It is none of those things. It is a chemical change happening inside the plastic itself, and in South Florida it happens faster than almost anywhere else in the country.It Is Not Grime, It Is Degraded PlasticNearly every headlight lens made since the 1980s is molded from polycarbonate, not glass. Polycarbonate is tough and shatter resistant, but it has one real weakness: ultraviolet light breaks down its molecular structure over time. Manufacturers know this, so every new headlight leaves the factory with a thin, clear UV-resistant coating baked onto the surface, similar in purpose to a clear coat over paint.That factory coating is sacrificial. It absorbs UV radiation so the polycarbonate underneath does not have to. Over years of sun exposure, the coating oxidizes, thins, and eventually fails. Once it is gone, the bare polycarbonate underneath starts absorbing UV directly, and that is when you get the yellowing, the haze, and the pitted, sandpaper-like texture under a light. No amount of washing, waxing, or wiping will touch it, because there is nothing sitting on the surface to remove. The surface itself has changed.Why South Florida Is Especially Hard on LensesUV exposure is cumulative, and it is a function of both intensity and hours of exposure per year. South Florida sits at a lower latitude than almost anywhere else in the continental United States, gets strong sun essentially twelve months a year, and adds heat on top of it. Heat accelerates the same oxidation chemistry that UV starts, so a car that lives outside here is working through its headlight coating on a faster clock than the same car in a northern state. Cars that spend their days street parked or in open lots are the ones that show cloudy lenses first, often well before the rest of the car shows its age.What Restoration Actually DoesA proper headlight restoration is a controlled version of what happens when you sand and refinish a piece of wood. The oxidized, UV-damaged outer layer of plastic has to be physically removed, not cleaned off, because by the time a lens looks cloudy, the damaged layer has some depth to it.The typical process looks like this:Wet sanding with a sequence of increasingly fine grits, often starting around 400 and working up past 2000, to remove the damaged layer without gouging the lensMachine polishing to bring back optical clarity and remove the sanding marksApplying a UV-blocking sealant or clear coat over the now-bare polycarbonateThat last step is the one people skip, and it is the one that matters most. Sanding and polishing a lens without resealing it is like stripping the clear coat off a car's paint and parking it in the driveway uncovered. The bare polycarbonate has no protection at all at that point, so it oxidizes again, usually faster than before, sometimes within months.Where DIY Kits Help and Where They Fall ShortDrugstore and auto parts store restoration kits can genuinely work on light to moderate haze, and they are a reasonable thing to try before paying someone. The honest limitations are worth knowing before you start. Hand sanding and polishing takes real elbow grease to get an even result across a curved lens, and it is easy to leave low spots that catch light unevenly. A rotary or dual