Works Good on Travertine
I used this on my 20'x20' travertine tiled porch and it removed almost all of the stains accumulated over the past 15 years. The deep rust and hard water stains that were set deep in the more porous tiles remained, though.<br />  As this product was more effective than CLR, vinegar solutions and various other cleaners, and cleaned everything else uniformly with no blotching or weirdness, I give it 5 stars. The only ways to get rid of the deep rust is some heavy acid application or replacement. I built some sturdy pottery racks/shelves (to prevent future stains) after sealing that cover them instead.
Rating: 5 stars