Home canning closure system

Claim 1

An improved home canning closure system provided for a container having a threaded neck portion terminating in an annular rim defining the periphery of an open mouth, said closure system including: a metal lid covering and closing the open mouth of said container and having a sealant means positioned around the periphery of its lower surface and adapted to sealingly engage the annular rim defining the open mouth of said container; and a plastic ring adapted to be placed over the metal lid and including an annular top panel portion and a skirt portion depending therefrom, the skirt portion incorporating threads adapted to engage the threaded neck portion on said container neck, the annular top panel portion including a downwardly and inwardly depending annular biasing flange which cooperates with the threaded engagement between the plastic ring and the container to form a spring means to maintain a uniform force on said metal lid to bias the metal lid into sealing engagement with the annular rim on said container, said annular biasing flange allowing the metal lid to flex out of sealing engagement with said container when the force on said metal lid due to the pressure within said container exceeds the uniform force of said spring means on said metal lid to thereby vent said excess pressure from said container.