You can polish the outside of the light but the lens is glued to the housing.If you do manage to seperate it without breaking it you may never get it to seal again .They are built to be air tight,if you do not get it sealed right you will end up with condensation inside your lamp.But if you do get it apart clean out the P.U.R OUT OF THE GLUE CHANEL,AND FILL IT WITH SILICONE,OR RTV.I work for Decoma one of the companies that makes the lamps for GM ,and they are all sealed in basiclly the same way.Good luck.