3M Aerospace Sealant AC-236 Class B are two-component, manganese dioxide cured, liquid polysulfide polymer system providing excellent fuel tank and fuselage seals. They have outstanding resistance to aviation gasoline and jet fuel, as well as resistance to chemicals and petroleum products common to the aircraft industry. 3M AC-236 Class B Sealants maintain flexibility and bond strength on most metal substrates like aluminum, stainless steel, steel, and many coatings under extremes of temperature, weathering and stress. The mixed compound is a thixotropic paste easily applied by extrusion, injection gun or spatula. They have excellent tooling properties.