MAPEI SM Primer is a ready-to-use, fast-drying, water-based, latex primer for use under MAPEI’s peel-and-stick sheet membranes on residential and commercial indoor or outdoor floors. MAPEI SM Primer greatly increases the bond of MAPEI’s peel-and-stick sheet membranes to concrete, plywood and other approved, properly prepared floors. It can be applied with a roller or brush, is white in color and dries clear.