Self-sealing fastener and method of use

A self-sealing fastener comprising:

• a shank extending longitudinally between a first end and a second end, the shank having an outer surface and a threaded portion;
• a head extending radially outwardly from the first end of the shank to an outer rim, the head having an underside surface adjacent to the first end of the shank and a topside surface opposite the underside surface;
• the underside surface of the head including a concave surface defined by an annular trough and a flat radial surface positioned radially between the concave surface and the outer rim;
• and
• a mastic sealant disposed on the outer surface of the shank adjacent to
• the first end having a first thickness,
• the concave surface of the underside surface of the head having a second thickness, and
• the flat radial surface of the underside surface of the head having a third thickness.

A method of installing a self-sealing fastener in a substrate, the method comprising the steps of:

• applying a first layer of mastic sealant to the shank that that extends from an underside surface of a head and comprises a threaded portion, of the self-sealing fastener, the underside surface of the head of the self-sealing fastener, or a combination thereof;
• applying a second layer of mastic sealant over the first layer of mastic sealant before the first layer of mastic sealant is fully cured such that the second layer of mastic sealant forms a protective skin over the first layer of mastic sealant, wherein a thickness of the second layer of mastic sealant is in a range of 25 to 50 percent of a thickness of the first layer of mastic sealant;
• curing the mastic sealant in the second sealant layer to a different degree than the mastic sealant in the first sealant layer, wherein the mastic sealant in the second sealant layer has a higher viscosity than the mastic sealant in the first sealant layer;
• and
• forcing the shank of the self-sealing fastener into the substrate wherein the second layer of mastic sealant ruptures as the second layer of mastic sealant makes contact with the substrate to flow the first layer of mastic sealant between the self-sealing fastener and the substrate and form a water-tight seal.