Headlight lenses today are all hardcoated polycarbonate, but the grade of plastic and hardcoat is vastly different than what is used for motorcycle windshields. Don't try to equate the two.
Honda uses GE Lexan polycarbonate with the FMR hardcoat. It's a great product, but it is also their basic, off the shelf, least expensive polycarbonate. If you have gotten 12 years out of it, then it has performed well, and it is time to just replace it. Even if you are diligent in not using harsh chemicals or abrasive towels, the sun oxidizes the hardcoat over time, which causes a haze, and thousands of micro cracks in the coating. The only way to prevent degradation is to just leave the bike in the garage.
Unlike Acrylic, uncoated polycarbonate is unusable as a comsumer grade product. It is too soft, and too easily damaged. That is why all polycarbonates have some type of hardcoat. And the hardcoat is too thin to rub out or sand. You will just go right through it.
Last edited by Sparky57; 06-17-2017 at 05:23 AM.