ER-921 is a surface-active agent used to reduce the water evaporation rate from the surface of newly laid concrete. It is designed to form a thin film to reduce rapid moisture loss from the concrete surface. ER-921 is spray applied in diluted form to fresh concrete flatwork to reduce the tendency for surface plastic cracking to occur. ER-921 aids and improves the workability and finishing characteristics of the concrete surface. ER-921 also helps extend the surface workability time for a given set of weather conditions.