Most plastic foundation is coated in beeswax to encourage the bees to build comb on it. It’s usually referred to as “wax-dipped” foundation. The really good stuff is double-dipped in wax. But sometimes the wax wears off if the foundation has been stored or banged around for a while. Some foundation, right out of the box, doesn’t have any wax at all. I had to deal with some of that stuff last summer and I was not happy. I would have been better off using foundationless frames. There are plenty of good reasons to use foundationless frames over frames with foundation. (I use a mix of foundation and foundationless frames in my hives.)
Having been stuck with 100 sheets of waxless foundation, and after managing to track down a 10-pound chunk of clean beeswax, I decided to wax the foundation. At first I tried to paint the melted wax on. Then I rubbed hard wax into the foundation. Finally I rubbed soft partially-melted wax into the foundation — the method I liked the most. Painting the foundation with an actual paintbrush may have produced the best results, but overall, I’m pleased with how my methods worked out. I’m sure there are better ways of doing this, but here’s a video of my first crack at it:
This is not a well edited video. I would normally try to cut something like this down to a few minutes instead of nine minutes, but I didn’t have time for that, so it is what it is. I’m also aware that this method of waxing foundation may not be the best method. But sometimes you have to work with what you’ve got.
June 24, 2021: More info at Waxing Foundation with a Heat Gun.