PCS Surface Retarder is a concrete surface retarder designed to retard the initial set time of surface mortar to expose aggregate surfaces. PCS Surface Retarder is a nonflammable, sprayable liquid designed for application to freshly placed, horizontal concrete surfaces. PCS Surface Retarder’s special, organic formulation reacts with the cement in the surface mortar to delay initial set and remain workable for an extended period of time. When the concrete has hardened to approximately 1500 psi, the retarded mortar paste may be removed by flushing with a gentle stream of water and/or removed by scrubbing with a stiff brush.