3M Aerospace Sealant AC-730 Class C is a fast cure, two-part, manganese-cured, non-chromate corrosion inhibiting sealant. Excellent for sealing faying surfaces of mating parts and sealing joints from passage of liquid or air, it provides and effective barrier against the common causes of corrosion on aluminum and between dissimilar metals. C-8 represents a minimum application life of 8 hours.