Premium flexible tile mortar Kerabond/Keralastic System is a high-performance, two-part system: Keralastic ™, a second-generation “flexible” acrylic latex additive, is used to enhance the performance of Kerabond ™, which is a premium-grade dry- set mortar. This system has exceptional bond strength, flexural strength, elongation and freeze/thaw durability. To ensure proper flexibility, always use a latex additive when applying a dry-set mortar over plywood or to set nonvitreous tiles. Premium flexible tile mortar Kerabond/Keralastic System is a high-performance, two-part system: Keralastic ™, a second-generation “flexible” acrylic latex additive, is used to enhance the performance of Kerabond ™, which is a premium-grade dry- set mortar. This system has exceptional bond strength, flexural strength, elongation and freeze/thaw durability. To ensure proper flexibility, always use a latex additive when applying a dry-set mortar over plywood or to set nonvitreous tiles.