Top-Cast Surface Retarder is a water-based, top surface retarder which does not require covering with plastic for protection. It is available in 12 depths of etch, each one color and number coded for safety and convenience. Top-Cast Surface Retarder is part of the Top-Cast decorative finish system. It is ideal for cast-in-place flatwork and the top surface of pre-cast concrete panels. The wide selection of grades available provides a comprehensive range of effects, from a simulated light acid wash or sand blast finish up to full exposure of 1-1/2" (38 mm) aggregate.