A simple soak in a permanent water proofing liquid like Watershed or a camp type silicone waterproofer will keep them floating for years.

Dip them in after you tie them. Let them soak up the liquid, then dry them overnight on a paper towel.

No playing around with mixing flamable stuff into wax. The gink type temporary fly floatants are messy and don't last long on bass bugs..working the bug knocks it all off pretty quick. That paste stuff just adds weight.

Knew a guy who was fond oftelling everyone that sealing the ends of the deer hair with heat would keep the fly floating. Wonder if he ruined as many as I did before he gave that one up.

And, no, RainEx will not help any of your flies float better.

Buddy