I just had a soapstone counter installed and they sealed it before they left. From what I've read, soapstone is oiled or waxed, not sealed. Does the sealer need to be removed if I want to use mineral oil to get an even patina?
A sealer might have been used because there are several types on the market. However, the sealer will dry in a few days. If you want to be sure of what you have just start all over by removing the finish. Most manufacturers recommend using #80 grit sandpaper to finish soapstone. I would use a random-orbit sander. You don't want to use an aluminum oxide sanding disc because it will not cut into the soapstone very well. I use the DuraDisc on hard surfaces because they work really well and last a very long time. You can finish the counter top with a 120 grit paper by hand in order to get closer to the faucet and other tight areas you might have. A lot of people use mineral wax to finish a soapstone counter top. I use Van's Beeswax instead. It seems to last a little longer and the sheen is not a wet glossy look.