Multicoat Products VPS1 1 gal VAPOR SHIELD Concrete Cure & Sealer is a chemical hardener, densifier, soluble chloride reducer used over bare concrete prior to cementitious overlay applications. Vapor Shield blocks and reduces vapor emissions through the concrete but leaves concrete breathable. It blocks hydrostatic pressure up to 20 psi. It does not alter the color of concrete, nor does it make the surface slippery or less slippery. Vapor Shield helps to reduce dust on floors. It reduces the green window from 28 days to an average of 5 days.