Abstract: Pistons for use in a dispensing cartridge, as well as cartridge systems including such pistons. The piston may include a body having a generally cylindrical configuration with a sidewall and a sealing lip extending outwardly from the sidewall. The sealing lip has a first portion dimensioned to have a first flexibility, a second portion dimensioned to have a second flexibility greater than the first flexibility, a sealing edge terminating the second portion, and a sealing bead positioned between the first portion and the sealing edge of the second portion, and the second portion configured to deflect relative to the first portion such that the sealing edge and the sealing bead have a contacting relationship with an inner wall of the cartridge when the piston is inserted into the cartridge. The sealing edge and sealing bead cooperate to prevent leakage during storage and to prevent blow-by during use.

Abstract: Pistons for use in a dispensing cartridge, as well as cartridge systems including such pistons. The piston may include a body having a generally cylindrical configuration with a sidewall and a sealing lip extending outwardly from the sidewall. The sealing lip has a first portion dimensioned to have a first flexibility, a second portion dimensioned to have a second flexibility greater than the first flexibility, a sealing edge terminating the second portion, and a sealing bead positioned between the first portion and the sealing edge of the second portion, and the second portion configured to deflect relative to the first portion such that the sealing edge and the sealing bead have a contacting relationship with an inner wall of the cartridge when the piston is inserted into the cartridge. The sealing edge and sealing bead cooperate to prevent leakage during storage and to prevent blow-by during use.