Zinsser Gardz is a water-based sealer designed for porous and problematic surfaces. It deeply penetrates, creating a hard, moisture-resistant film that seals and stabilizes surfaces like damaged drywall, new drywall, plaster, and even old wallpaper adhesive. It's known for its ability to bind down chalky surfaces and prevent issues like blistering, tearing, and uneven paint appearance when redecorating.