Hi All, I've been getting conflicting info in my search for answers, so maybe someone here can help. We are installing a carrara marble tile backsplash. The tiles are 4"x12". I'm pretty sure we are using white thin-set, but should it be modified or no? Also, what size trowel should we be using with a 4"x12" tile? We are planning a 1/8" grout line, using unsanded grout. Should we seal the marble before grouting or after? Thanks for any help you all can offer!