A new adventure here. We just stripped the carpet off one of the downstairs rooms. There is quite old unfinished fir flooring. The adjoining living room had more vertical grain. This seems to have more flat sawn. It does have a sub floor under it. The room is about 12x24. I've put down plenty of wood flooring but have not done the finish and most of that work was many years ago. The condition of the floor is quite good as it had linoleum over it which had not been glued down. There are some water marks on one corner, but the floor is good there. I will rent a RO floor sander and edger. What grit should these be finished to? What finishing process would you suggest and what materials?