Have Dino Rachiele build you a custom sink please.

Water and wood do not mix on a permanent basis. Epoxy or other film forming finish will crack as wood swells and shrinks normally. You can not stop wood from behaving like wood. And you can not stop water from winning. You need to build this with high maintenance in mind. Drop the sink every couple of years to sand and add a new coat of whatever you choose, and replace the caulk.

thank. you live_wire - do you know much about Cedarshield? My woodworker has been considering it as a way to stop the wood from expanding and contracting, but unsure if this will be compatible with other treatments.

Nothing. Absolutely nothing, prevents wood from acting like wood. Shipbuilding woods that are chosen to be around water like teak or mahogany, have high oils content that naturally resist water penetration. That doesn’t prevent them from expanding and contracting. It’s the fact that they are in a constantly moist marine environment that does that.

I installed a birch wood countertop on my last home. I LOVE wood counters. I had also used Waterlox after reading so much about it but was not impressed. Around my undermount sink I put 12 coats of polyurethane. That seem to hold up well, but if I had to do it over again I would’ve installed a sink that went to my backsplash, and had a hole for my faucet.

I have since moved and no longer have wood countertops, but I have a solid oak top for my island, I just oil it and I love it. Good luck with your project.

https://www.houzz.com/discussions/5919611/experiences-with-rubio-monocoat-for-kitchen-countertops#n=11

Here is a small discussion I had with some folks that had experience with RMC.

Ideally in this situation wouldn’t you want a drop-in sink with a deck for the faucet to protect your counter edges? This is the Kohler Vault. I’m not a fan of double bowl sinks, but as you are this should fit the bill.

IMO an undermount sink with a wood counter is not ever ideal. I had this sink with my wood counters and the only finish I did for the wood is a really good oiling once a month wood has an enzyme that kills bacteria if you seal it that stops working. BTW I ran a catering biz from that kitchen for 8 yrs. before we sold those counters are still in great shape12 yrs after the sale.

Sure. Let us know how it goes!