The key to keeping yer polished plastic lights looking new after polishing is sealing them with some clear spray after polishing them clear.
I don't have U-Pol clear available to me...so I just used some Rustoleum clear coat spray paint (non-UV) from Walmart about 8 months ago when I polished my headlight lenses. I was not able to find a source fer the UV resistant clear coat spray paint locally so I just got the normal clear spray. The clearness of the lens is holding up much better than one with no added coating on the lens. Although it's yellowed just a little, it's not hazed over like when I bought the vehicle early this year.
March 2009...
April 2009...
December 2009...
Glassylite is the ultimate lens restoring product kit on the market that includes a clear coating sealant and may be a better kit choice fer the DIY consumer.