3M Polyurethane Seam Sealers are 1K moisture curing polyurethane products designed for seam sealing applications in car body repair. 3M Polyurethane Seam Sealer are high-solid adhesive 1K sealer products, which cure to a tough, permanently flexible material within 24 hours when exposed to atmospheric moisture. (The speed of cure depends on bead thickness and environmental conditions). Temperature resistant from -40°C to +90°C (temporarily up to 120°C). Ideal for sealing medium and wide car body seams, welding seams or even suitable for use on wood or plastics. Can be applied directly to bare steel, can be used as a weld-through sealer. This application must be done whilst the product is still wet (within 35 mins of application). The product must be left to cure (min 45 mins!) prior to application of water-based base coats.