I recently pulled up three layers of old vinyl flooring in my kitchen to find 40 year old heart pine tongue in groove unfinished floors. I'm sure at the time of istallation it was considered a poor grade or something to cover up because the rest of the house is oak flooring. My problem is water stains from years of mopping, what appears to have been a leaky dish washer, and a leaky ice maker line. Is there anything at all that will lighten or remove the dark water lines? I really hate to cover them back up.