Modern cars use polycarbonate headlight lenses. They are very durable, lightweight, and can withstand significant impact without cracking. Occasionally, however, they can turn hazed and discolored (yellow). Clouded yellow headlight lenses reduce headlight brightness, and new lenses can be expensive.

The yellowing occurs from the UV protection clear coat on the lens fails over time and the polycarbonate underneath is then exposed to UV rays, and in turn it sustains damage. This damage is oxidisation and it happens due to climatic influences, UV radiation, acid rain, de-icing salt and road dirt. Also using methylated spirits to clean headlights will eventually lead to lens damage and discolouration, and with time the clear plastic will eventually turn matt and yellowed.

On the internet you may find many tutorials advising how to fix yellowing headlights including using toothpaste, WD40, sandpaper, bug spray, methylated spirits, sandpaper. etc. Most of these methods don’t work at all, or work only for a very short time.

Proper repair method can ensure the headlights are properly restored, otherwise you’ll have to go through the whole process every few months.

The only reliable method of fixing yellowed headlights is to sand the lens with very fine sand paper, then buff the lens out and apply a new UV clear coat sealer. This new UV coat will ensure that the repair lasts for many years.

We recommend using products only from reputable manufacturers, like this SONAX Headlight Restoration Kit, or this 3M Headlight Lens Restoration Kit.

Sonax developed their product to ensure it is specially adapted for the materials of modern vehicles and is simple to apply. The set contains four small pieces of abrasive paper, a special headlight lens polish and a sealant – everything needed for the application. This set is sufficient for about four applications.

The 3M restoration kit requires a household drill (1200-1600 rpm). It contains various graded sanding pads, pad holders, buffing pads, polish and detailed instructions.

Needless to say, yellowed headlights can also be replaced with a new set of headlights, but this can cost hundreds of pounds.

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