GacoFlex A4121 is primarily for use as a temporary primer over GacoRoofFoam as a protective covering until an additional layer of GacoRoofFoom or a GacoFlex coating can be applied. A4121 is a water-borne, single component elastomeric acrylic coating characterized by excellent hardness, strength, adhesion and water resistance. Quick dry. Drying time is 1 to 2 hours.