Gasket Sealant
A liquid adhesive or paste applied to gaskets or mating surfaces to enhance the seal and prevent fluid or vacuum leaks.
Gasket sealant (or gasket dressing) is a liquid adhesive, paste, or spray applied to pre-formed gaskets or metal mating surfaces to enhance their sealing ability. Unlike RTV silicone which forms a complete gasket on its own, sealants are typically used to help position paper, cork, or rubber gaskets and fill microscopic imperfections in the metal surfaces.
Gasket sealants come in various formulations: non-hardening sealants (such as aviation gasket sealant) remain tacky and allow for easy disassembly, while hardening sealants cure into a rigid bond for permanent assemblies. There are also aerosol spray tack sealants used to hold large gaskets (like head gaskets or oil pan gaskets) flat during installation.
Choosing the correct sealant is critical; using a sealant that is incompatible with the fluid (such as using an oil-soluble sealant on a coolant passage) will dissolve the seal and cause leaks. Mating surfaces must be thoroughly cleaned and degreased before applying the sealant to ensure proper adhesion.