I am a car fanatic and have used one of these dusters on my cars for the last decade or more.  As long as the surface is dry, it works wonderfully.  Once some contaminants start to build on the paint, use the duster, then some Quick Detail with a microfiber cloth to get the paint really clean.  My cars always look new with these things.  I just traded in my 2004 RX-8 after 2.5 years of using the duster, and it still looked absolutely new.  I now use it on my 2006 Lancer Evolution and, again, the car looks brand-new (which it is).  I love them.