After the cure period, there should be no residual oil.

Depends on the oil you use.

There are 'drying' oils and non-drying oils.

Mineral oil, vegetables oil...are non drying oils. i.e., they won't polymerize over time.

Examples of drying oils are tung oil, walnut oil, linseed oil.

The nondrying oils will leave the greasy marks.

If we oiled our counters, it would be so that we could chop right on them. So...are tung, walnut or linseed oil food safe?

Does anyone have knowledge as to whether overmounting or undermounting the sink is better on a wood counter?

I'd go with the undermount, just for the sake of wiping down the counter. Also this allows you to see all the wood, and not have some hidden under the sink rim, where you won't know if it is rotting or not, until it is too late!
If mine, I would use a food safe oil (mineral, bee's wax or combo of) I have this on both my Maple prep area counter, as well as my Mesquite bar tops. It does NOT rub off on papers or paperwork, unless you put so much on it won't absorb into the wood, which is unnecessary... Just my two cents, Chris

I have plank maple counters in my pantry. I used Daily's Profin oil finish (food safe) on it and it has held up beautifully for nearly five years. It looks as good today as the day it was installed. My sink is an IKEA drop-in farm sink. I have never had any water damage next to the sink or anywhere on my counters. Water just beads up on the counter.

I'm also planning a wood counter with undermount and have done a lot of research and have spoken with butcher block dealers about it. They all recommend something like Waterlox or marine varnish. I've heard good things about the Osmo products as well but I haven't done much research on them.

While these finishes aren't considered food grade safe, that doesn't mean you can't make a sandwich or lay food directly on them. It just means you shouldn't use it as cutting board. I'm guessing you wouldn't use your counter that way regardless of the finish you use.

We have a walnut plank island top. We have a mineral oil finish...and it DOES leave marks on papers left on it. Of course, it is worse right after we oil it...but even months later you can't leave a newspaper or a sheet of loose leaf on it. I actually want to refinish my top with Waterlox. The oil looks fine, but I really want a more durable finish that wipes up better. Every time I use a damp sponge on the top, I feel like I am taking some of the oil off. If I had a sink on it, I would DEFINITELY use Waterlox.

Someone on GW has a wood countertop on an island with a sink. They use one section of the wood (I think it is walnut) as a cutting surface. It looks great.

FWIW, I would not want anything except an undermount prep sink. There is just too much cutting and chopping and brushing crumbs into the sink for the disposal

If you do a wood countertop and a positive reveal on the undermount (as Shelayne did), you could have a matching cutting board with a food safe surface to place across the sink opening or on the countertop as you wished. It would be flush with the surface when over the sink. A neat idea, I think.

Edited to add: Here's the link to the countertop I mentioned above. It is gorgeous. A lot of good info and ideas here! But I am afraid it would not be a good surface for doing homework, darn it.

Here is a link that might be useful: Wood countertop used as a cutting board

This post was edited by Bellsmom on Thu, Jan 15, 15 at 11:53

I had a day full of busywork and spent some of my "mind time" thinking of your island. This idea occurred to me:
Could you delineate an area near the sink (on the range side that would be food safe and finished with an easily replenished finish) by routing a shallow groove around it? Maybe even plan to use the whole lengthwise half of the island on the sink side? Then finish that area with an appropriate food safe finish?

The other part of the island could be finished with Waterlox or tung oil (which I love to use) or whatever. Something that would not stain papers left on it.

I am not sure if the surface sheen would differ too much between the two, or if one or the other finish might darken the wood differently over time. Or if the narrow routed line might be too intrusive. Might be worth trying out on a scrap? And let it age a while as the kitchen comes together?

And, after all, the whole surface can always be resanded and refinished if whatever you do doesn't work.

This post was edited by Bellsmom on Thu, Jan 15, 15 at 16:42