Fugemasser

Fugemasser, commonly translated as sealant, is a pliable, adhesive compound used to seal joints and gaps. It adheres to many construction substrates and cures into a flexible, water-resistant layer that accommodates movement, helping to prevent air and water ingress and to provide a finished appearance.

Common chemistries include silicone-based, polyurethane, acrylic, polysulfide, and epoxy sealants. Silicone sealants cure by moisture in the air and remain highly flexible and UV-stable, making them suitable for glazing and exterior use. Polyurethane sealants cure via moisture as well and generally offer strong bonding and chemical resistance but may be more challenging to paint. Acrylic sealants are water-based, paintable, and often used indoors for non-structural joints. Polysulfide sealants provide chemical resistance and are used in specialized applications, such as tanks and aircraft. Epoxy sealants are more rigid and used for high-strength sealing in industrial contexts.

Applications cover building and construction to seal joints between materials such as glass, masonry, metal, and tile. They are used around windows and doors, in bathrooms and kitchens, in expansion joints in concrete, and on roofs and gutters. Proper surface preparation is important, often including priming and the insertion of backer rods to control depth. Curing times vary by formulation, substrate, and environmental conditions, and some formulations are paintable while others are not.

Safety and environmental considerations include VOC content, exposure to isocyanates in some polyurethanes, and the need for proper ventilation and personal protective equipment during application. Cured sealants are generally considered inert, while disposal and cleaning should follow local regulations.