QUESTION

Matching Grout Color - What are your thoughts about using acrylic paint over unsanded grout? We installed an absolute black granite tile floor and the grout turned out to look dark grey.

We added colorants, used the blackest grout, etc. Now, to avoid a lawsuit we need to make this grout as black as the absolute black tile as we stated on the contract. We were told epoxy paint is too hard to keep off of the granite and that we should use an acrylic black paint.

ANSWER

ANSWER - I don't know of any acrylic black paint that would be recommended and would have any assurance to lasting.

Normally what is used is a grout colorant that is epoxy based and matches various grout colors. One well known grout colorant is made by Aqua Mix http://www.aquamix.com.

The blackest grouts are normally epoxy grouts that can be applied thin like Laticrete Epoxy grout http://www.laticrete.com.

There are special stone joint fillers made by Akemi http://www.akemina.com to match granite stones, but it is designed for filling tight joints.

No matter how you go about it, it will be tedious and a challenge. Make sure you sample an area for the client to make sure they will accept it before doing the whole floor.

Grout never matches the grout exactly. You should have said that you would try to match the stone as close as possible, but the grout color will not be an exact match and there may be shade variation within the grout.

Good Luck!