Thanks!
Funny thing happened.
As I was doing the final touches on the grout, the owner's son came out and asked if the tan grout would turn gray...?
I said no, it would be the color of the sample on the bag of grout that they purchased and provided, along with the slate tile.
He was kind of miffed.
I had to explain that "someone" had to look at a grout sample and request the warehouse man to bring it out for them, as this was not bought from a self service facility.
He said she wanted gray...
She never brought it up, was happy and complimented the work...And paid me.
Who knows
KT