Painting old floors

Q: My hundred year old fir floors are worn through in many areas. The pros say they cannot be refinished. Can I paint them a dark espresso? If so, what paint should I use and what would be the process?

A: I don’t know why you were told the floors can’t be sanded. If you want to paint them, I would go to the local paint store for directions. Zinsser has an amazing primer.