I know about this because my husband sells marble and granite for countertops, flooring, etc. If you like that the mortar is shiny- then go to a tile store or home depot and buy stone soap. You should never use household soap- even like disnwashing soap because it with actually rough up the surface and make it loose it's shine. I always cringe when I see people using windex on granite- in a couple of years their counters are no longer shiny because they are actually scratched by the chemiclas in teh cleaning product. Of course if you don't really care if it says shiny or not you could use household soap.It's purely a question of appearances!