I started sanding our floor with 36 grit paper on a orbital sander and it was not cutting though everything so I was told to go to a 20 grit which i did then went over with 60 and 80 but I see some swirl marks(looks like if you would have taken an ink pen on paper and made squiggle marks)is there any way to get these out before i put poly on the floor. This is an old house with lots of uneven boards also.

When you drop down that low you have to progressivly move back up thru the grits without skipping more than one. if you started with 24 then you should have thrown a 40 in the mix before the 60. 60 wont take a 24 scratch out its too deep. Also uneven floors are hard on orbital machines they dig on one corner whenthe hit a high or low spots.

Thank you for your reply.