(Also see Substrates)
When tiling over existing ceramic tile, lightly sand and then clean the existing tile. New ceramic porcelain tile or natural stone can then be installed using a polymer-modified, cement-based mortar, such as MAPEI’s Ultraflex 2, MAPEI’s Ultraflex LHT or MAPEI’s Ultraflex LFT, or a two-part, cement-based mortar and liquid additive, such as MAPEI’s Ultraflor Plus mixed with MAPEI’s Keraply , or MAPEI’s Kerabond T mixed with MAPEI’s Keraply. 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.