That's a good question! Solid white to me would mean the discoloring is all the way through, but I'm just guessing. I would get a plastic headlight polishing kit and try it, you have nothing to lose. If it wasn't so bad I'd say use aircraft windshield polish. If the head light cleaner works, aircraft windshield polish could take the swirls out. Just a suggestion. Convertible rear window polish from an auto store is another avenue to pursue also. PJ