"I used this product on a newly done entryway and kitchen floor. The mapei grout did not dry in a uniform color (an issue I read about after purchasing and using it) and rather than spend hours un-grouting and re-grouting the floor with a risk of it still being miscolored I opted for this stuff.It worked really well, although can be a bit time consuming.I used a QEP sealant applicator from Home Depot, the kind with the foam wheel. While this worked well and may have sped up the process a bit, you'll still want a toothbrush or foam brush for many parts (hard to reach places or small crevices).I let the colorant sit for 2 hours before cleaning it up off my tile. I was liberal with the water (it says to mist, i pretty much just poured water on it) and scrubbed it up with a brillo pad. It took me quite a while to clean up all of the tile, so some of it sat dry on there for as long as 4-5 hours and still came up fine.Some Notes:- if you know what brand of grout you have and want a close color match to that, do some googling and you can find Aqua Mix colorant and sealer that is color matched per brand (I had mapei charcoal color and just opted for the Aqua Mix kind and there is a difference in color)- the mileage on this stuff will vary greatly depending upon grout width, but I was able to use about 3/4 of the bottle on roughly 200 square feet of 1/4 grout in a hopscotch (12"/6") pattern which has more grout lines than a typical straight 12"/13" checkerboard or diamond pattern.In the end I would highly recommend this rather than re-grouting, in the end I think it's cheaper or about the same cost with a guarantee to be uniform in color."

       "we had a grout (ironically made by the same company) for our slate kitchen tiles which refused to dry with a uniform color even after thorough mixing. Originally we thought this was because of bad installers, but after digging out the original grout and grouting our tiles again- it dried with all different shades of grey! Then I found out about grout stain- bought this product from amazon - and it works perfectly! It colored and sealed to uniform perfection. We meticulously painted the grout with small brushes, were careful to immediately wipe up the tile edges that got any stain on them, and now everything looks perfect."