wood floors

What type of wood and what caused the stains?

Possibilities are:

oxalic acid two part wood bleach chlorine bleach

See:

Bob, As the other poster indicated, if you can find out what caused the stain, the better off you will be in selecting a "bleaching" mechanism. What I have found to be dam near impossible to fix is urine stains from a cat. Not sure why, but this seems to be the toughest staining problem to fix. I gave up and replaced those boards in my house. Previous owner I guess was not too clever at taking care of thier animals. When you do select something keep in mind most of these stains are not a fixed darkness. You will have to be careful not to "overbleach" a area. That will stick out just as bad. I would use any solution in a diluted state and try repeated treatments rather that one heavy treatment. This way you can adjust the approach based on the results.