The plastic lens over your headlight is as cloudy as a bathroom mirror right after a shower. No wonder you can’t see. There is a way to fix this.
Clearing away haze
Most cars and many trucks today are manufactured with headlamp assemblies that use quartz-halogen bulbs plugged into the back of a large plastic reflector. The outer surface of these headlamp modules is molded polycarbonate plastic. That plastic is much lighter than glass and far more resistant to stone chips and cracks. However, after a few years of exposure to sunlight and atmospheric chemicals, polycarbonate has a tendency to get hazy. Severely neglected lenses can actually pit and develop a network of fine cracks, called craze, which makes the job of fixing them tougher. It’s worth a shot, though—and you’ll need only a few bucks’ worth of materials to get the job done. Sure, these assemblies are easy to replace, but they can be very expensive. A pair of lenses for a luxury car can cost as much as a thousand dollars. No thank you!
Fortunately, there’s a simple and inexpensive solution. Unlike glass, the polycarbonate plastic can be polished back to a surface as smooth as new, in a procedure that won’t take more than a half-hour.
Wash your car to remove any surface dirt. Waxing it, at least within a foot or two of the headlamps, is a good idea, because drips and droplets of the abrasive polishing compound are less likely to adhere to a freshly waxed surface.
Head out to the store and buy some blue, low-tack painter’s masking tape, the handy stuff that peels off easily. Mask the area around the headlamp that needs to be polished. You may want to remove nearby trim, especially chromed metal or chrome-finish plastic, because you’ll be polishing and sanding with materials that can destroy the chrome.
There are prepackaged kits intended specifically for the task. 3M and Permatex both sell a kit containing everything you need for around 10 bucks. You can also buy the sandpaper and polishing compound individually. If you only need to do one pair of headlights, it’s cheaper to buy the kit instead of the sandpaper one sheet at a time.
Assuming your lens is only moderately obscured. Start the repair with polishing compound and a flannel or microfiber cloth. Smear some compound on the lens and polish in a circular motion. As the polish gets ground into the cloth and dries out, it lifts the haziness right off the lens. Most of the compound eventually winds up on the cloth, but it probably takes about 10 minutes of rubbing per lens, so don’t be in a rush. If you have an orbital polisher, you can use that with a lambs wool or terry cloth pad. Don’t polish the paint off nearby surfaces. Simply proceed with compound until the lens is shiny.
Okay, you’ve been polishing one corner of the lens for a few minutes, and it’s better—but not perfect. The lens surface is far too degraded for the polishing compound to rescue it. There are still pits that you can feel and see.
Soak a piece of 1000-grit wet/dry sandpaper in cold water for 10 minutes. Lightly sand the lens in straight strokes. Methodically cover the entire lens surface, always sanding back and forth in one direction. Keep the surface wet while you work. Be careful not to damage nearby paint or trim.
Sand until the pits, discoloration and scratches you’re trying to eliminate are gone. This takes time. Also, don’t be afraid to dry the surface with a towel and check the uniformity of your sanding. When you’re done, clean and dry the area.
Now perform the same operation with 1500-grit wet/dry sandpaper, this time sanding at right angles to your previous work. Again, be methodical. Keep the paper wet, cover the entire surface and then clean up to remove any abrasive powder. Repeat the procedure, every time at right angles to the last sanding, with 2000-, 2500- and 3000-grit wet/dry. Clean up one last time. You might want to touch up or redo the masking tape along the way if it starts looking a little tattered.
Now go back to your compound and flannel to hand-polish out the final patina of scratches. Your lens should look like new—shiny and clear.
Be certain you clean off all the abrasive polishing compound. Now wax the lens thoroughly with a paste car wax. This last step will keep acid rain, dirt and road salt from attacking the plastic, at least for a while.
Happy illuminated traveling!