Canning closure and method

A one-piece reusable closure for a container having a body portion and an upwardly extending neck portion which terminates in an upper circumferential sealing lip and defines a mouth and having helical container thread means on the outer surface of said neck portion, said closure comprising:

• a central cover section having an inner surface and an outer surface and a depending peripheral skirt having helical skirt thread means for threadingly engaging the container thread of a container;
• an annular gasket comprising a resilient, compressible closed cell foam resilient at temperatures up to about 250.degree. F. at the periphery of said central cover section, said gasket being bonded to said central cover section for confronting the periphery of a said sealing lip;
• limitor means displaced from said gasket for limiting the extent of threaded engagement with said container thread means whereby compression of said gasket against said lip is limited to a predetermined degree;
• and a portion of said central cover section being outwardly dished, but being movable, under gas pressure to an inwardly dished configuration and capable of generating an audible sound upon movement.

A one-piece reusable closure for a container having a body portion, a circumferential flange extending outwardly from said body portion, and an upwardly extending neck portion which terminates in an upper circumferential sealing lip and defines a mouth and which has a helical container thread means on the outer surface of said neck portion above said flange;

• said closure comprising:
• a central cover section having an inner surface and an outer surface and a depending peripheral skirt having helical skirt thread means for threadingly engaging the container thread of a container;
• an annular gasket comprising a resilient, compressible closed cell foam resilient at temperatures up to about 250.degree. F. at the periphery of said central cover section for confronting the periphery of a said sealing lip;
• a limitor means integral with an edge of said skirt for limiting the extent of threaded engagement with said container thread means whereby compression of said gasket against said lip is limited to a predetermined degree;
• and a portion of said central cover section being outwardly dished, but being movable under pressure, to an inwardly dished configuration and capable of generating an audible sound upon movement.

A method of canning comprising the steps of:

• providing a container having an upper circumferential sealing lip which defines a mouth and having container thread means in the vicinity of the mouth;
• providing a one-piece closure comprising a flexible, outwardly-dished central cover section terminating outwardly in a depending peripheral threaded skirt for threadingly engaging said container thread means, said closure having an annular gasket bonded to said closure adjacent said skirt, said gasket comprising closed-cell foam material resilient at temperatures up to about 250.degree. F. for compression against, and sealingly engaging, said lip around the periphery of the entire lip, said closure having limitor means displaced from said gasket for limiting the extent of threaded engagement with said thread means;
• filling the container with a desired quantity of product to be canned;
• threadingly securing said one-piece closure to said container to form a seal between said gasket and said lip and until said limiting thread engagement is reached so as to limit the maximum extent of gasket compression and to thereby seal said product within said container together with a small volume of gas;
• then heating said container and said product contained therein to a predetermined elevated temperature and thereby generating within the sealed container pressure sufficient to break the seal between the gasket and the container and to vent at least a portion of said gas volume to the surrounding atmosphere;
• then cooling said container and thereby re-effecting the seal between said gasket and said lip without further manipulation of said closure so as to maintain a subatmospheric pressure in said container.

A method of canning comprising the steps of:

• providing a container having an upper circumferential sealing lip which defines a mouth and having container thread means in the vicinity of the mouth and having a circumferential flange extending outwardly from said container below said container thread means;
• providing a one-piece closure comprising a flexible, outwardly-dished central cover section terminating outwardly in a depending peripheral threaded skirt for threadingly engaging said container thread means, said closure having an annular gasket bonded to said closure adjacent said closure skirt, said gasket comprising closed-cell foam material resilient at temperatures up to about 250.degree. F. for compression by, and sealingly engaging, said lip around the entire lip, said closure having limitor means integral with an edge of said skirt for limiting the extent of threaded engagement with said container thread means;
• filling the container with a suitable quantity of product to be canned;
• threadingly securing said one-piece closure to said container to form a seal between said gasket and said lip and compressing said gasket until said limiting thread engagement is reached so as to limit the amount of gasket compression and to thereby seal said product within said container together with a small volume of gas;
• then heating said container and said product contained therein to a predetermined elevated temperature effective to prevent spoilage of said product and thereby generating pressure therein to force a portion of said contained gas to break the seal between the gasket and the container by compressing said gasket to vent said gas under gasket to the surrounding atmosphere;
• then cooling said container and thereby re-effecting the seal between said gasket and said lip without further manipulation of said closure so as to maintain a subatmospheric pressure in said container.