Zinsser Wallpaper Cover-Up is a 3-in-1 product that acts as a primer, sealer, and stain blocker, specifically designed to be used over wallpaper. It effectively obliterates the wallpaper print, creating a smooth, matte off-white finish, and prevents blistering caused by moisture from subsequent paint layers. This allows for the application of any colored emulsion paint directly over the treated wallpaper.