Food safe wood finish for wood used to make lacto-fermented vegetables

I have non-treated hardwood planks. I cut disks out and sanded them down and they are quite cool. I would use them with aquarium rocks on top.

My question is do you think I could use a food safe finish or do you think I should treat them like a meat butcher block. I don't think my first question showed up. These disks would be submerged in a salt brine, and sometimes with a live starter culture for various lengths of time. Thank you Jorge

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Arbutus Ron here...

As long as there is no meat, using a food safe wood finish like walnut oil will help preserve the wood when you make your sauerkraut.