I've been scraping all the propolis from my hives and dumping it in a 3 liter can I keep some beeswax in to work with. Surprisingly the propolis settles out when the wax is melted. I've seen propolis melt in the Solar collector, at some where around 225°F (107°C).
The reason for the Rosin is Paraffin, a long straight carbon chain, doesn't stick to the wood very well. Small branching carbon chains bind to the wood better and don't "sweat" out of the wood when it gets hot in sunshine. If anything, you can get hold of Microcrystalline waxes
that will help to bind the long chains to the wood fibers.
I might not be doing it right, but I've dipped some small pieces of woodware in beeswax and haven't seen any problems. Of course by the time I got around to actually DIPPING the parts in the limited beeswax I have, I'd already put plenty of scraped propolis into it.