Rust-O-Leum makes it and you can buy on Amazon or Home Depot or EBay. It does leave a light film on the paddle but it makes the water run off the paddle faster as you lift it from the water on each stroke. I followed the instructions and mine has lasted quite a few trips. I don't use my paddle as a push pole or hit it on anything usually to damage the coating. You just apply more as needed per instructions.
If you constantly get wet from paddling then try it. It can't hurt. Some may no want to put it on a $300 paddle though. For $300 the water better flow off it faster than my $40 paddle with NeverWet.
USAF Retired and Fishing!