My first response, what about rain-ex?
Then I looked at the article..
"You'd think it would be easy, but apparently not. "What about Rain-X?", you might ask -- and I did too. But apparently Rain-X is designed to be used on glass only, not polycarbonate motorcycle helmet visors."
Oh. Glad I didn't put it on my visor. Was just looking at the bottle last night thinking about how I need to do this on the windshield and visor. Maybe I'll pick some of this stuff up instead.