May leave white residue upon drying
Definitely cleans and lifts dirt from slate floor.  I used a scrub brush and then used sponge to absorb the dirty water. However, upon drying it left a white residue which I then had to go over a second time with a wet sponge.  As the floor area in nearly 300 sq ft, I only did a section at a time.  For the second effort,  I used a shop vac to suck up the dirty water and made sure I got all of the water by going over the wet area a few times.  This made a difference as the amount of white residue was limited to a few spots.  Would recommend using this product, just may need to figure out how to get treated area as dry as possible to avoid white residue as much as possible.
Rating: 4 stars