How do you clean grout that won’t come clean?
How do you clean grout that won’t come clean? Mix 3 parts water to 1 part bleach and apply to the grout with a damp sponge. Wait 10 minutes and soak the grout again. Wait another 10 minutes and rinse with water. If your grout remains black, you might have to resort to a little construction 101 and re-grout the tile.