I have hardwood oak floors that have a light surface coating. I just took up old carpet and there are dark blackish stains on the floor, I think a dog urinated on the carpet. Is there any other method of attempting to remove these stains other than sanding them out?
You should be able to safely wash most sound finishes with a pH neutral cleaner as discussed in the cleaning article in the Floored News section of this site. I’m sure you have tried washing the stain out of the wood, but by now it has discolored the wood itself, below the floor finish.
You will need to start by trying to sand them out. Sanding with 80 grit sandpaper will remove all the finish and some wood. If you are really lucky the stain will dull and disappear as you sand down through some depth of wood. But don’t go as far as making a gouge in the wood floor, there are better ways to remove this stain, if it is deep in the wood.
You can certainly try bleaching with the strongest wood bleach available. You will need to remove all the wood floor finish off just this stained area, by chemical stripping or sanding. Try a wood bleach called Klean Strip at http://www.kleansrtip.com. It will turn the dark areas an off white color.
All these treatments contain water so the floor will need to dry overnight and then be sanded with 100-120 grit to smooth the wood but be careful not to sand out the bleached effect.
The off white colored spots will need a light colored wood stain to blend them in to the rest of the floor. It’s quite an art. You will want the color to blend in with the final finished color of the floor, not the bare wood. Then touch up with the same finish the floor is coated with. If you don’t know what that finish is, read the second part of the floor maintenance article in the Floored News section.
And lastly, major repairs, or replacements. Or a combination of all of these methods. Find an old (or young) floor master in your area, that does these things, and will give you advise in person. But you certainly can do the bleaching yourself. You can also read my repair article in the Hardwood Authority section, to see if you can do the repair yourself.
As always your Most humble servant, Joseph, the Wood Floor Doctor.