We are staining some exterior 'cultured' stone, see pic below. Stain on right side, original color on left. H&C Stain, available locally at Sherwin Williams dealers.
https://www.hcconcrete.com/
Tried some of the stain on a basement and garage floor, but it doesn't absorb. Quick test see if water soaks in or beads up. If it beads up, you likely have to grind it first.
