Use RedGard sealer by first applying the product to corners and seams using a paintbrush and then using a paint roller to apply two successive coats to flat wall surfaces. Ensure the greatest amount of coverage by rolling the first coat of RedGard onto the walls using horizontal passes and using vertical passes to apply the second coat after the first coat dries. Let dry RedGard stand an entire day before installing tile over the surface.
Before applying RedGard, fill in any cracks in the surface to prevent the membrane from tearing or cracking. Do not use RedGard itself to fill in cracks, as the product shrinks during drying.
RedGard gives a very clear indication of when the initial layer is dry and the surface is ready for the second coat. The product is hot pink in color when wet, but turns a deep red color as it dries. The color change is a useful feature of the product, but the manufacturer suggests waiting several hours between successive applications.
Because RedGard shrinks slightly as it dries, the manufacturer suggests inspecting RedGard for any pinholes, cracks or tears before applying a successive coat. If you find any imperfections in the coat, apply RedGard only around the flawed area, and do not apply an entire additional coat.