We bought this to clean a Rubio treated floor that had no maintenance for 10 years and was nearly black from NYC soot. Using the Rubio Soap at the usual dilution, plus spraying a bit extra, and two passes - the result was incredible. Not exactly like new, but a major improvement. And the dirty water tank was black like the pictures. We then buffed in the Rubio Maintenance Oil and the floor looks great. The brushes are very soft, and the vacuum removes the water right away so it does not soak into the wood any more than mopping.