some inks can be dissolved with denatured alcohol, but I'm not sure what that would do to the 21th Century covering. I routinely mark covering with a sharpie and then remove it with a paper towel and a squirt of Alcohol, but that is on Monokote and Ultrakote. Try it in a scrap and see.

Iwould forget the idea of the mineral oil. I think the 21 Century is somewhat porous and that would allow the oil to migrate under the covering and break down the adhesive and soak the wood. Oil and covering just don't mix.

Don