QUESTION

How to Darken Grout - Need to darken a 2-day ago grout from natural (grey) to a darker shade. It is for the floor. The tiles are a matt-finish greenish. Will a color-enhancing grout sealer 'stain' or discolor the tile as well? These are just under 2" x 2" tiles so for sure we don't want to apply the grout sealer by hand. :-) Any suggestions>

ANSWER

ANSWER - You need to experiment to determine what you can do.  The grout may be light color because too much water was used in mixing or cleaning it up so it pulled out the pigment or maybe it is because it dried at a different rate where it is lighter.

You can try using a grout enhancer over the grout and tile to darken the grout, but immediately buff dry the tile and grout surface with a lint free cloth.  Do this as a test in an inconspicuous spot in case it doesn't work well enough.

You can use an epoxy grout colorant but you have to apply it to the grout joints only.  You have to wipe off any excess that gets on the tile.  There are applicators for them to make it easier. Test it out first to see if it works well enough. Can't have sealer on grout if you apply grout colorant.