Loctite 5923 Flange sealant, non-hardening, brush. Loctite 5923 is a red-brown viscous fluid with a typical alcohol scent. This fluid dries up slowly and after the solvent evaporates, it forms a soft sticky film. This product is used to seal parts with little gaps, treated surfaces and threaded joints in the industry, air craft building, and marine fleet. Application of Loctite 5923. Coating of rigid gaskets. Treated surfaces with little gaps. Threaded joints. Air craft engines. Ship engines. Silicone.