I've used automotive 100% Caranuba Wax, but it takes multiple coats of it, 6-10 in my case. I'm still a novice at this, so your mileage may vary. I purchased Evercoat liquid PVA from my local marine supply store (West Marine). They also sell West Epoxy resin and mold release wax too. You might want to look up a marine supply/repair in you area.
Here is a link to my thread, pages 1 and 2 show the products I used.
http://www.rcuniverse.com/forum/m_6794670/tm.htm
Hope that helps.
-Jorden