We have wood floors (some kind of western fir tree) throughout the house. We decided to sand them all clean and put some kind of clear finish on them. Unfortunately, the upstairs floors had a couple coats of paint on them.
We rented a sander from the local hardware store and started the project. We went through oodles of sand paper! The paint just gummed it up! What was underneath was beautiful though.
The newly sanded floors being protected with Osmo Oil (http://www.ivyhillosmo.com/ ). These are all natural oil and wax based floor treatments. Worked great!