Now that is funny... I was wondering the same thing today. I accidentally touched it with my pen. It took me about 5 minutes to get rid of the mark it left and it's still not entirely gone. It somehow seems to soak it right in. I guess I have to be more careful. Oh, btw, regular dishwashing soap and a microfiber cloth is what I took. And as I said it's ALMOST gone. So if anyone has a better suggestion... gimme gimme 😀