If you are doing it yourself you will most likely sand the floor 3 times!!!
1st with a course sand paper, which will take up most of the old finish, if not all!!! Then empty dust bag!!!
2nd sanding is with a medium grit !!! empty dust bag!!!
3rd sanding is with fine grit!!!! Save enough fine dust to patch nail holes etc:
After apllying 1st coat of urathane mix fine dust with urathane, [paste like] fill nail holes, let dry and then sand!!!
If using oil base urathane you should apply 3 coats,fine sanding inbetween each coat!!!
Remember that when using the edger it does not get into the corner as you will notice!!! use a furniture stripper such as 5F5 in the corners scrape and sand !!!!
