Sikaflex-221 is a high-quality multi purpose non-sag 1-c polyurethane sealant that cures on exposure to atmospheric humidity to form a durable elastomer. Sikaflex-221 bonds well to a wide variety of substrates and is suitable for making permanent elastic seals of high adhesive strength. Suitable substrate materials are wood, metals, metal primers and paint coatings (2-c systems), ceramic materials and plastics