Q: My home is about 50 years old. Our hardwood floors were covered with water for about 3 weeks thanks to hurricane Katrina. The floors are attached to a wooden sub flooring with tongue and groove and a nail every 10 inches. There is some very minor buckling but a black spot appears at all the nails. Can this be removed by sanding?
A: Tough to know for sure if the black marks can be removed. Best guess is probably not. I must confess, I am astonished that you say your hardwood floors have only minor buckling after being covered with water for 3 weeks.
My honest feeling is that this entire floor will have to be removed, including the sub floor, and replaced. Otherwise it could take months to fully and properly dry. Perhaps the best thing you can do is find someone with a moisture meter and check what the condition of this floor is. 7-9% Is normal for hardwood. If the reading are up 14% or, in this case perhaps over 20% the floor is really quite wet. If the entire thing does not buckle, one thing is certain… If and when it did dry out, you will have some major shrinkage and gapping.