Hi, we moved into a condo a couple of years ago - there are travertine tiles throughout the 2400 sq. ft. The tiles aren't so bad, but the grout is disgusting. I have spent hours on my hands and knees with little brushes, to no avail. Also, we have been using a steam mop on the floor, and I think the dirt from that just collects in the grout. So now it is dark grey and terrible looking, mostly in the kitchen. The rest of the house isn't so bad. I recently tried mixing a paste of oxiclean and water and that actually worked in a small area, but I'm concerned about the affect this might have on the tile. Anyone have any solutions to this, so I can finally have a clean-looking kitchen floor? Thanks so much!