Wood slab centerpieces

Do you want to use them again? Then yes. Do you care if they get wax/food spills/wine spills? If yes, seal. Do you want them to be shiny/semi-shiny? Then yes. You're not placing anything edible on them, right? If so you'll need a food grade sealant.

@mel- those questions are very helpful in answering this! Thank you!!

My dad made ours. He sanded them and put several coats of shellac (or something like that) on them. But he only sanded and shellac'd one side since the guests were only going to see one side of the rounds.

Yes, definitely seal. My mom used them for a work gala last year and they cracked within six months.

If you are not going to use them again, it doesn't matter if they crack 6 months from now.

We sealed ours.

I cut my own, and I might seal one side. If they were cut from a fresh log they will possibly crack in time, as the wood dries out that is a possibility. Keep in mind there are different types of sealant. You can always get a matte finish instead of glossy.