Aging Plastic Headlights: How to Restore Headlights with Headlight Cleaners

In the past, automakers designed headlight lenses made from glass so they were limited in the size and shape they could produce. Since then, auto manufacturers began designing cars with plastic or polycarbonate headlight lenses. This modification mainly occurred due to the change in the design of cars---cars became lighter and more aerodynamic, plus plastic was by far less expensive to produce than glass. Today this plastic material is the chosen choice because it is very light and can be transformed into unlimited sizes and shapes to satisfy new car designs.

Polycarbonate has its advantages but also has its disadvantages---namely oxidation/discoloration. To the naked eye one cannot tell that these plastic lenses are actually a porous material that expands ever so slightly when it gets hot. Degradation of the lens occurs over time. Having your headlights on or being exposed to the heat of the day causes the pores to open allowing debris from the road to get in. Debris, together with a combination of environmental factors such as the sun (UV rays), smog, acid rain, car exhaust, and harsh chemicals used to wash you car can cause the plastic headlight lenses to become oxidized.

Plastic oxidation leads to lens discoloration, which transforms new, clear, bright, shiny plastic to a dull yellow tint that appears to be foggy, hazy, or cloudy. This process (oxidation), as described above, not only becomes an eyesore but also is unsafe. Because of the degradation of the plastic lens, less light passed through resulting in diminished visibility during night driving. The car owner either had to deal with these cloudy yellow, oxidized headlight lenses posing serious safety issues or purchase expensive replacement headlights costing hundreds or thousands of dollars.