Cutting Board Finish: Oil Vs Varnish

Seems like cutting boards are on everyone’s minds this time of year, probably because we’re all making holiday gifts. And with that comes the yearly flood of questions in the forums about cutting board finishes and what is or isn’t “food safe.”

The answers usually go something like this:

Person 1: Mineral oil is the only finish you should use.
Person 2: NEVER put varnish on a cutting board! Are you crazy?!
Person 3: Mineral oil and wax. End of discussion.
Person 4: Here are 14 paragraphs of information you didn’t ask for.

Okay, I’m generalizing for fun, but you get the idea. Some of these discussions probably stem from advice I gave years ago in Episode 7, A Cut Above, where I said my favorite finish for end-grain butcher blocks is salad bowl finish, essentially a thinned varnish. But there’s an important caveat.

I’m Not Building a Film

The argument against varnish on a cutting board usually goes like this: knives cut through the film, moisture gets underneath it, and eventually the finish starts to fail. I agree. That’s why I don’t build a thick film.

Instead, I dilute the varnish enough that it soaks deeply into the open end grain. Think of the end grain as a bundle of straws. We’re filling those straws with finish rather than coating the surface with a thick plastic layer.

I apply the diluted finish heavily and let the wood absorb it. On an end-grain board, you may even see finish coming through the opposite side. Then I wipe away the excess and let the board dry overnight. I repeat that process three or four times, sanding lightly between applications. Eventually the wood stops absorbing much finish. At that point, I stop. I don’t keep adding coats just because the can says I can.

How Does It Hold Up?

Pretty darn well. My boards resist water much better than boards treated only with mineral oil. Mineral oil can certainly work, and adding wax improves its water resistance, but it remains a finish that needs regular renewal.

And yes, my varnished boards get knife marks. They should. If your cutting board never gets cut, you’re probably not using it. After about 18 months of regular use, my board still looked quite good. The center had dulled a bit and there were plenty of knife marks, but there was no thick finish peeling or flaking because there was never much of a film there to begin with.

When a knife cuts into the surface, it’s mostly cutting into wood whose pores contain cured finish.

What About Maintenance?

This is one of the main reasons I like this method. I wash the board with light soap and water after use and occasionally wipe it down with white vinegar. When the surface finally needs some help, I take it back to the shop, sand it thoroughly, and apply another light coat or two of diluted varnish.

A mineral-oil board usually needs oil much more often, sometimes monthly or even more often with heavy use. Maybe I’m just lazy, but I know which maintenance schedule I prefer.

So Is Mineral Oil Wrong?

Not at all. Mineral oil is the classic cutting board finish. It’s inexpensive, easy to apply, and easy to renew. If that’s what you like, use it. I simply prefer the results I’ve gotten from a penetrating varnish treatment on end-grain boards. It gives me better water resistance, less maintenance, and a look I prefer.

I should also make one thing clear: my observations come from years of using these boards, not from controlled scientific testing. Finishing advice is full of claims that get repeated until everyone assumes they’re facts. So do your research, look at several good sources, test things for yourself, and add your own experience to the mix.

EDIT – Since the writing of this article, my preferences have changed. I still believe the above information and arguments are valid but for those looking for a finish that’s a little healthier and more natural, check out this video: The Best Food Safe Finish