Plastic headlight restoration
Headlight restoration or Plastic headlight restoration is the act of refinishing aged headlight lenses that have become discolored or dull due to oxidation primarily due to UV light and other environmental factors such as road debris impact (stones, sand, etc.) rain, and exposure to caustic chemicals. Over time the protective hardcoat breaks down with UV degradation and wear from abrasion, etc. If left untreated the headlights will eventually develop small surface cracks, a condition referred to as crazing. The effectiveness of the headlight in terms of light output measured by LUX is greatly diminished, by as much as 70%. This condition which results in hazy and discoloured lenses is known for causing reduced night time visibility for travelers as the condition becomes worse. It is possible for cloudy and hazy headlights to be restored to a like new condition and represents typically a far more economical alternative than replacing the lens.
Additionally, headlight restoration extends the usable life of the headlight assembly, can be repeated if necessary and is considerably "greener" than disposal and replacement of headlights. It doesn’t make any sense to dispose of headlights that can be simply and cost effectively be restored, and by doing so greatly reduce Co2 emissions.
Profession Headlight Restoration Services
There are an increasing number of professional headlight restoration services that charge approximately US$60 to US$125 to restore both headlights on a vehicle. Replacing the lens can be much more expensive. For example, some brand new headlight lens assemblies can cost over $2600 each (plus the labor to replace the lens) (Example: 2003 Porsche 996TT, dealer verified price as of 9/15/2014, $2633.00 per lens assembly; 2006 Infiniti M35, dealer price verified as of 9/15/2014, $1286 per lens assembly.) There are many do it yourself headlight restoration kits available on the market, however, most of the kits do not restore the headlights nearly as well as an expert headlight restoration service. The main reason for this is because most of the do it yourself kits do not include the proper tools needed for professional results. Furthermore, some professional headlight restoration shops are applying a urethane or acrylic clear coat to help protect the plastic lens from UV exposure after the headlight lens is restored.
DIY Headlight Restoration Products
There are many "do it yourself" headlight restoration kits available for purchase. A few of the major brands that produce these "kits" include 3M, Turtle Wax, Sylvania, Headlight Wizard, Meguiar's, Mothers, and Rain-X. Most of these kits require multiple stages of wet sanding to remove the oxidation of the headlight lens, usually with descending level of grit (course to fine). Some kits include a UV sealant which is said to protect the lens of the headlight longer. Kits with the UV sealant include some of the 3M, Sylvania, and Headlight Wizard. It should be noted that typically the DIY sealant requires regular periodic reapplication and is not equivalent to the original OEM hardcoat applied during manufacturing. Another common option to delay the aging process of headlight lenses, is the use of press and snap-on headlight covers, or laminates with adhesives that can be applied over the headlight lenses, such as Paint Protection Film sold by 3M.
In the US a number of patents have been filed for headlight restoration products including  which provides a substantive authoritative document detailing the condition, processes to remedy, kits available in the market and limitations and benchmark testing.
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