Naftoseal® MC-780 Class A

Fuel Tank Sealant

Naftoseal® MC-780 Class A is a two-component, manganese-dioxide cured, liquid polysulphide polymer system providing excellent fuel tank and fuselage seals. It has outstanding resistance to aviation gasoline and jet fuel, as well as resistance to chemicals and petroleum products common to the aircraft industry.

Naftoseal® MC-780 Class A maintains its flexibility and bond strength on most metal substrates like aluminium, stainless steel, steel, titanium and many coatings under extremes of temperature, weathering and stress.

The mixed compound is a pourable, slightly thixotropic liquid easily applied by extrusion, injection gun, spatula or brush. It has excellent tooling properties.


  • Sealing integral fuel tanks
  • Repairing integral fuel tanks
  • Sealing fuselages


Naftoseal® MC-780 Class A fulfils the requirements of the Airbus Specifications AIMS 04- 05-001 and 04-05-012.

Download Naftoseal® MC-780 Class A technical datasheet

  • Application Life and Cure Time

    (at 23°C/50% r.H.)

    Application Life and Cure Time
    (at 23°C/50% r.H.)
    TypeMin.Application TimeMax.Tack-Free TimeTime to Shore A 35
    MC-780 A - 1/20,5 hours< 4 hours< 8 hours
    MC-780 A - 11,0 hours< 7 hours< 10 hours
    MC-780 A - 22,0 hours< 14 hours< 24 hours

  • Typical Physical and Application Properties
    Typical Physical and Application Properties
    Viscosity at 23°C,
    Brookfield, Spindel 7
    50 - 200 Pa.s
    (10 Umin-1/rpm)
    max. 400 Pa.s
    (10 Umin/rpm)
    Mixing ratio by weight1009
    Mixing ratio by volume1006,4
    Non-volatile content92 ± 2 %
  • Typical Physical and Performance Properties
    Typical Physical and Performance Properties of Cured Compound
    (after 14 days/23 °C)
    Specific gravity1.25 g/ccm max
    Ultimate Shore A Hardnessmax 50 Shore A
    Service Temperatures-55 °C / +130 °C
  • Typical Values of MC-780 Class A
    Typical Values of MC-780 Class A
    ConditioningTypical Values in N/mm2
    Typical Values in %
    14 days 23 °C≥ 1,5≥ 200
    6 months fuel / 23 °C≥ 1,5≥ 200
    Peel Strength (in N/25mm - % )
    AdherendConditioningTypical Values
    Al + Epoxy Primer14 days 23 °C
    300 h jet-fuel at 100 °C
    ≥ 120 N/25mm – 100%
    ≥ 120 N/25mm – 100%
  • Surface Preparation

    To obtain good adhesion, clean surfaces with appropriate solvent (reclaimed solvents should not be used) to remove dirt, grease and processing oils just prior to sealant application. Use lint-free rags or paper towels that are free of oil.
    Always pour solvent on the cloth to avoid contaminating the solvent supply. Clean one small area at a time, quickly wiping it dry before the solvent evaporates to prevent redeposition of oil, wax or other contaminants.
    Usually, in the case of most epoxy resin primers, surfaces need not be additionally prepared with an adhesion promoter to improve adhesion. PUR and EP topcoats as well as composite components should be pre-treated by the NAFTOSEAL MC-115 Adhesion Promoter.

  • Cleaning of Equipment

    Immediately after use or before the sealant cures, wash equipment and tools with a solvent. NAFTOSOLV FN will completely dissolve uncured, semi-cured and fully cured NAFTOSEAL sealants. It provides a method for completely removing NAFTOSEAL® and other polysulphide sealant contamination (see separate Data Sheet).

  • Packaging

    The material is supplied in the following containers

    DesignationBase Compound Content/PieceNo./Case
    Kit 10100 cm³12
    Kit 25250 cm³12
    Kit 50500 cm³12
    Kit 1001.000 cm³4
    Techkit 5555 cm³24
    Techkit 130130 cm³24
    Unit 162162 litri9 x18 | Base + Hardener
    Drum162 litri162 | Base + Hardener
  • Storage

    The shelf life of NAFTOSEAL® MC-780 Class A is 6 months from date of manufacture, when stored at temperatures below 26 °C in its original unopened container. Storage at lower temperatures increases shelf life.