hi guys I have a job with some large porcelain tile 2x3 . Looks to be very absorbent really . The stuff looks rough lots of dirty areas most likely from janitor using dirty mop bucket and just laying in the dirty water. I used some prochem alkaline cleaner the green stuff and let it sit for a bit . As I walked over it to scrub grout lines I could see the almost white impression from my shoes in the tile but the scrubbing won’t break the rest of the soil down . I have used a floor scrubber and still those foot prints will show up. Where I left a grout brush the tile lightens up too. I have let the product sit for 20 min and still same problem. This stuff is all over . Any tips. The area by the toilet cleaned up ok . But it’s like the tile is absorbing the dirt but only where I step does it work lol. If you zoom in on the picture of the lobby you can see the spots .



