MasterCast 141 - Multi-purpose admixture for cementitious systems and bonding agent How does MasterCast 141 work? MasterCast 141 is a (SBR) styrene-butadiene copolymer latex specifically designed for use with cement compositions. It is used in mortar and concretes as an admixture to increase resistance to water penetration, improve abrasion resistance and durability. It is used with cement as a reliable water-resistant bonding agent.