A specialized, fast-setting modified thin-set mortar for use as a bond coat within tile assemblies that is optimized for use with Schluter® membranes and boards. Schluter FAST-SET™ is smooth and creamy, as well as easy to handle and spread. It is sag-resistant and ideal for setting tile on both horizontal and vertical surfaces. Schluter FAST-SET™ is suitable for use with ceramic, porcelain, and stone tile, including large and heavy tile, in conjunction with Schluter®-Systems’ uncoupling and waterproofing membranes (e.g., DITRA, DITRA-HEAT, KERDI, etc.), the Schluter®-Shower System, and KERDI-BOARD. Schluter FAST-SET™ can be used in both interior and exterior systems and is available in both grey and white.