This material is designed for fay surface sealing applications. It offers as much as twenty percent weight savings, per unit volume, over traditional sealants used for these purposes. The cured sealant maintains excellent elastomeric properties after prolonged exposure to aircraft fuels both jet fuel and aviation gas, and will resist limited contact to diphosphate ester based hydraulic fluids. PR-1782 Class C is a two-part, manganese dioxide cured polysulfide sealant. The uncured material is a thick liquid suitable for application by roller or spatula. It cures at room temperature to form a resilient sealant having excellent adhesion to common aircraft substrates.