Tiemco dry shake is the best one that I've found, I did A LOT of testing on floatants, and this one was amazing, quite frankly the fly wouldn't sink! After 70 full immersions under water it still popped back up, then somebody opened the door and the draft blew the fly across the surface!
Not cheap, but if you want a fly to float perfectly, buy it. It does turn the fly white though, so get the dun coloured version if you can. Less embarrasing to ask for too.
http://www.thefriendlyfisherman.co.u...glues-etc.html