We have been using extruded polystyrene foam form liners on tilt-up panels. During stripping this material breaks up and some of it usually sticks to the concrete. This has to be peeled off piece by piece, a laborious job. Is there a way to eliminate this sticking problem and the time-consuming cleanup?

There is if you would be interested in exposing some aggregate at the same time. Gayle Johnson of Ray Hoopes Concrete and Stan Hanson, developer of the H & H Industrial Park in Phoenix, Arizona report that they found an easy solution to their sticking problem. Instead of the usual form release agent they applied a specially formulated water-based retarder to the surface of the polystyrene form liner. This delayed the hardening of the surface layer of concrete and permitted easy stripping. After stripping, the retarded mortar was washed from the panel surface with a hose, exposing aggregate (which had been specially selected) and producing pleasing shadings and textures. This produced economically an unusual combination sculptured-and-exposed-aggregate finish.