It now looks like we put in new tile
This product exceeded expectations.  We had grout that even when cleaned was a dingy gray. It now looks like we put in new tile. We used OxyClean (1 part to 4 parts water) and a toothbrush to clean first.  Applied the Grout Refresh in a fairly thin bead about 1/3 the length of a tile and used a child's toothbrush to spread.  Followed directions for spraying water after 30 - 60 minutes to remove any excess Grout Refresh on the tiles which worked well.  I used a dry microfiber cloth and dropped the excess Grout Refresh from this process into a bucket of water.
Rating: 5 stars