Closure seals

Claim 1

A TWO-PIECE BLANK FOR FORMING A VACUUM SEAL WITH AN EXTERNALLY SCREW-THREADED CONTAINER COMPRISING A DISCLIKE RIGID VACUUM CAP MEMBER, GASKET MEANS CARRIED ON ONE FACE OF SAID CAP MEMBER FOR SEALING AGAINST THE MOUTH OF SAID CONTAINER, AN OUTER CUP-SHAPED CLOSURE SHELL MEMBER, FORMED OF THIN DEFORMABLE DUCTILE METAL AND COMPRISING A TOP HAVING A CENTRAL APERTURE THEREIN OF LESS DIAMETER THAN SAID CAP MEMBER, AND A SKIRT ADAPTED TO HAVE A SCREW THREAD FORMED THEREIN BY BEING INWARDLY DEFORMED BETWEEN ADJACENT THREAD FORMATIONS ON THE CONTAINER, A SECURITY BAND AT THE LOWER MARGIN OF SAID SKIRT FOR ENGAGEMENT UNDER A SHOULDER ON THE CONTAINER, SAID SKIRT HAVING A WEAKENED PORTION BETWEEN SAID SECURITY BAND AND THE UPPER PART OF THE SKIRT, AND A SHOULDER IN SAID SKIRT DEFINING A GROOVE BETWEEN THE TOP OF SAID CLOSURE SHELL MEMBER AND SAID SHOULDER WITH THE EDGE OF SAID VACUUM CAP MEMBER BEING TRAPPED IN THE GROOVE, THE DIMENSION OF SAID GROOVE BETWEEN SAID TOP AND SAID SHOULDER BEING GREATER THAN THAT OF THE EDGE OF SAID VACUUM CAP MEMBER, WHEREBY UNSCREWING MOVEMENT OF SAID CAP AFTER THREAD HAS BEEN FORMED IN SAID SKIRT WILL RESULT IN RAISING SAID CAP MEMBER OUT OF ENGAGEMENT WITH THE CONTAINER MOUTH ONLY AFTER A PREDETERMINED ANGULAR MOVEMENT OF SAID CLOSURE SHELL IN THE UNSCREWING DIRECTION.