Calacatta viola is a marble that comes from one of Italy’s oldest quarries. The unique burgundy purple veins through the stone are irreplaceable and a true work of art in each tile.
Castelli puts a Resin backing on some of their stones to reinforce/strengthen it during processing, shipping, and install.
This Resin backing requires the use of an Epoxy Thinset or Epoxy Additive during installation
Common stones that will have this are Nero St. Gabriel, Rosewood, Calacatta, Statuary, etc.