I would be interested in your results. My husband and I just pulled up our carpet last night to see our original 1910 oak wood floors. Some are in great condition and others have water stains on them. We are a bit concerned that one stain may actually be from the ground up as that portion of the floor is over a crawl space. I wonder if the oxalic acid will work for these stains.
Our other problem is that the floor is a bit uneven in spots. i'm wondering if those can be even out with sanding?