TOP-STOP is a spray-applied, water-soluble surface retarder designed to slow the set of surface mortar in concrete to expose the aggregate. It temporarily halts the set of Portland cement at the surface while the concrete below the surface cures normally. TOP-STOP is economical and easy to use, producing beautiful exposed aggregate concrete flatwork with consistent results. TOP-STOP is non-flammable and VOC-compliant.

Apply TOP-STOP with a low-pressure sprayer immediately after screeding when concrete has lost its sheen, or as soon as bleed water has disappeared. Apply only after all finishing operations are complete. Avoid puddles and over spraying.
Cover concrete with wet burlap or plastic sheeting to prevent drying out. Secure the edges of the plastic sheeting to prevent ballooning. Do not use curing compounds. Concrete admixtures which affect the setting time should not be used without first conducting a test patch. Periodically check concrete to determine depth of retarded mortar, making sure concrete hardens.

Within 12-24 hours of application (depending on temperature and humidity), remove burlap or plastic sheeting one section at a time and wash the retarded surface mortar using a low-pressure garden hose and stiff broom. Do not use excessive force. Test a small area to determine if depth of retarded mortar is at desired level. If the depth is greater than desired, allow the slab to cure longer before exposing the aggregate.
Stone color can be enhanced using EXPO-GLOSS® exposed aggregate surface sealer from W. R. MEADOWS