If you prefer a high alkaline, solvent fortified chemical to deal with heavy soil on hard surfaces...you want Cobra! The original tile and grout cleaner, it removes years of built up grease, dirt and stains! Nothing Stronger! Dilute it 1:1 for tough jobs, more for lighter jobs! You'll see the dirt start to lift out of the grout even before you begin using your machine. Rinse well. Let the Cobra bite through your old finish. If you prefer a high alkaline, solvent fortified chemical to deal with heavy soil on hard surfaces...you want Cobra. The original tile and grout cleaner, it removes years of built up grease, dirt and stains! Dilute it 1:1 for tough jobs, more for lighter jobs! You'll see the dirt start to lift out of the grout even before you begin using your machine. Rinse well.