I'm getting ready to lay some porcelain "slate" looking tile in an entryway, along with matching real slate border tile sheets. I grout floated the same porcelain tile in our master bath with no problems. I'm a little concerned about using the grout float for the slate border as there are lots of little grooves and crevices. Any suggestions for keeping it clean? Should I sponge it as I go, or will this have a detrimental effect on the grout(to much water)?