The 3M Fast Cure 5200 Cartridge is a high performance polyurethane that becomes tack free in one hour and fully cures in approximately 24 hours. The seal is extremely strong, retains its strength above or below water line. Stays flexible too ? allows for structural movement. Stress caused by shock, vibration, swelling or shrinking is effectively absorbed. Has excellent resistance to weathering and salt water. Won?t sag or flow in vertical or horizontal seams.