Try heating it in mineral oil. That's non-digestible and food-safe. It's used in cutting boards and as a laxative.

I don't know how oil interacts with cement, though. If it's just a solvent, it probably won't harm it.

Thanks daisy. I talked to someone else who said to use mineral oil too. He said to do a 50-50 mixture. So I melted the beeswax and added the mineral oil and stirred it together. Once it hardened it was again pretty hard to deal with. I think I'll just need to soften it some to work it into the casting surface.
I'm surprised other people aren't making food safe bowls with their leaves. Or maybe they are and I just couldn't find it in my search.

Elaine, Other people are making food safe bowls from their cement creations but some of what people do and sell is proprietary. Certain liquid floor waxes can be used. I've added a link to a concrete countertop sealer. Did you look at the cement or concrete associations web sites for information on sealing? Did you try using a heat gun on your wax concoction? Billie

Here is a link that might be useful: sealer