Excuse me for reopening an old thread but the discusion was about filling in nail holes with glue. I have installed a pre-finished 2 1/4 in. red oak flooring and had to face-nail some of the boards. Did anybody ever use sawdust mixed in with polyurethane as a nail hole filler? Does it work?

Also my threshholes are not pre-finished. Should I fill the holes first, let them dry and then polyurethane the boards or give the thresholes a coan of poly first and then fill the holes?