I can tell you that painter's tape uses an acrylic based adhesive. The steps you have already taken are sufficient to have removed any remnants of the adhesive. I wonder whether having had tape over the oiled surface just provided greater oil penetration underneath? Regardless, my guess is that if you live with the counter and it's marks for a few weeks the marks will fade on their own with normal use.

No solution from me here, just commiseration. I too have painters tape marks on my soapstone counters, these from where the fabricators marked the stone for cutting (so they were only on there a few days, but some of that outside in the sun at the fabricators shop). You can only see them when the light hits the island in a certain way, and I've just decided to live with them. Acetone didn't remove them, so my guess is that the adhesive somehow oxidized the stone a bit. I've had my counters for more than 6 months, and the marks haven't changed in that time. I just notice them a bit less.
I didn't pursue having my fabricator address the issue (even though they created it) because I had other interactions with them I wasn't happy about. I suspect re-honing the island all over would take care of it, but it isn't noticeable enough for me to want to go that route and risk them doing some other kind of damage.
In your case, I'd probably try waxing, to see if it removes or reduces the contrast.

Ok, this sounds extreme, but what the heck.

1) try oiling everywhere but on the tape marks. Leave the oil on for a long time, then wipe to see if it makes a difference?

2) Get the widest painters' tape you can, same brand, and cover your entire counter with it. Set cardboard down on it so you don't peel it by accident, and leave it for ... a long time. Or put the tape down in stripes and have the most unusual, natural soapstone counter in the entire world.

3) (I hate being told this:) Leave it and learn to live with it. I actually do find I see the trees for the forest while things are going in. When it's all said and done, I frequently forget what I'm worried about.

I had a mystery stain on my soapstone counter (beautiful Belvedere, also from M. Tex) that only became apparent after I had my ucl's installed, a few months after the countertop was put in. It was a circle, as if a bottle or can was placed there and left a dark ring. So maybe it was there when I got the counter, maybe I put it there, who knows. I tried cleaning it with a scrubby and mild cleaner but it wouldn't go away. So I decided to call it patina and live with it, and went about my standard counter care routine, which was just cleaning with a damp sponge as needed and oiling the counter every few weeks. Now the stain is gone. Gone gone, even after the oil wore off. Don't know when or how. I would suggest that you go ahead and oil or wax your counter and see if, in time, the dark spots disappear. The wax just sits on top of the stone, it doesn't penetrate, and it can be removed easily with a mild cleaner, so I don't think you need to be concerned that you're somehow making the stain worse or more difficult to remove.

I also had a non-mystery stain, totally self-inflicted. I got a microscopically thin ribbon of silicone sealer on the soapstone at the edge of a cabinet that sits on the counter. I went at it gently with a razor blade and a little ball of steel wool, looks fine now and no change in the texture of the finish.

Good luck and I hope you let us know what happens!

marcia59:

Go back to the fabricator and ask him for some soapstone slurry. This is the stuff created when soapstone is cut wet. It will be a paste or powderish. Make sure you get some uncontaminated by granite or estone if he fabricates those products.

Gently rub the slurry over a test portion of the affected area. If it doesn't do anything, try being less gentle.

Trebuchet is right. If the stone slurry isn't abrasive enough use some 150 or 250 grit honing powder which is aluminum oxide. It is more abrasive then the soapstone slurry. Test a small area first until you solve the issue. if one of the slurries work then make sure you are cleaning as you go.
Don't leave all the cleaning for last-dry slurries are harder to clean. After you detail clean and the tape marks are gone you can wipe on mineral oil. Buff the excess off.

I think the tape pulled off not only the oil, but the powdered soapstone particles down the surface pits (that the eye can't see, but they're there) left over from the honing process.
The finest particles may or may not ever be completely removed, but the tape did a job just in one well-defined area, so it sticks out. That's why a very light sanding will reverse the damage; it puts the dust back in the surface.
This is from the guy that honed his own soapstone, so FWIW.
Casey

Any luck? This happened to me. Not sure what to do