Zinsser Peel Stop triple thick primer is a water based acrylic binding primer designed to penetrate and stop previous coatings from peeling. Peel Stop Triple Thick is three times thicker than regular primers when applied properly, so it fills and seals cracked, weathered and peeling surfaces, creating a smoother, more uniform surface for finishing. It dries to a white finish to provide contrast for application of finish coats. It has excellent flexibility to allow for natural expansion and contraction on wood and other exterior surfaces.