(Also see Substrates)
In order to tile over existing ceramic tile, the tile should be lightly sanded and then cleaned. New ceramic porcelain tile or natural stone can then be installed with a polymer-modified cement-based mortar such as MAPEI Large-Format Floor & Wall Tile Mortar, MAPEI Large Tile & Stone Mortar or a two-part cement-based mortar and liquid additive such as MAPEI Uncoupling Membrane Mortar mixed with MAPEI Polymer Additive. Always use a white mortar for installations of new natural stone and clean the grout joints while the mortar is still soft in preparation for grouting.