Naftoseal® MC-780 Class C is a two-component, manganese-dioxide cured polysulfide
polymer system with reduced density providing excellent fuel tank and fuselage seals. It is
designed for interfay surface sealing and wet riveting of fuselage components and has
outstanding resistance to aviation gasoline and jet fuel, as well as resistance to the chemicals
and petroleum products used in the aircraft industry. Additionally, it was developed for a
service temperature between -55 °C (-67 °F) to +130 °C (+ 266 °F) and withstand a shortterm temperature of +182 °C (+360 °F).
Naftoseal® MC-780 Class C maintains its flexibility and bond strength on most metal
substrates like aluminum, stainless steel, steel, titanium, composite and many coatings under
extremes of temperature, weathering and stress.
Naftoseal MC-780 Class C combines low viscosity, for ease of mixing, with a high thixotropy
giving good application characteristics. It can be effectively applied by extrusion, by injection
gun, or by using a roller coating technique. The low viscosity means that it is easily squeezed
from interfaying surfaces during the assembly process. It has a unique „self-filleting“
characteristic.
Naftoseal® MC-780 Class C can be mixed by MCI-Mixer or by appropriate 2-component
mixing and dosing systems.
The curing time may be reduced considerably by increasing the temperature (up to 60°C or
140°F max).
