What finish is on the butcher block counters to protect from stains? I have a new BB island that has only mineral oil on it so it can be used to chop. I won't be using it for that & want to protect it.

We chose an oil finish as well. I've used a water-based polyurethane finish for other counters that you will not be cutting on.

I hope no one minds me inserting a thought here. I am a bit of a finishes nerd. I would recommend a penetrating oil finish for your butcher block, whether you are chopping or not. It's more natural looking, and is far more repairable than film forming finishes like polyurethanes. If you must have more protection from chemicals (stains) a film forming finish may be better for you. In this case, talk to a professional finisher about catalyzing (2 part) finishes like conversion varnishes. They are available in waterborne chemistry as well as solvent, and provide more protection than a polyurethane that is 1 part. Best of luck!

Thank you for your comment. I wish I understood what you are saying: "catalyzing finishes like conversion varnishes". I have consulted the builder, Sherwin Williams staff, and my floor finisher. Builder was clueless, his painters were clueless. Sherwin Williams was clueless but suggested Teak Oil like is used on wooden boats. The floor guy (finished my reclaimed heart pine floors) said to first try tongue oil and if that wasn't to my liking, put on Zinsser Bull's Eye Shellac. To clarify, I do not want to use it as a cutting board. I want to protect it from stains and water marks. I have so far put on one coat of tongue oil. It has brought out some brightness in the wood. I will repeat at least one more coat as instructed and perhaps more.

Exactly, tung oil is the way to go. You can keep your finish up with tung oil as well. Just wipe more on as needed when the finish gets damaged or dry. If using a pure tung oil, cut it at least 50% with a solvent. See realmilkpaint.com for good instructions. They sell a pure citrus solvent that is natural and "green". Always wipe away standing oil after application.
If you would like to know more about catalyzed finished, feel free to contact me. I'm surprised no one knew about them. DO NOT use shellac on your countertop! It will not do well in this application as a topcoat!