Abstract: A recipient having an axially upwardly open neck formed with at least one radially projecting neck thread is capped by fitting a circumferentially thermally shrinkable sleeve around a plug, fitting the plug into the open neck to block same, fitting the sleeve also around the neck over the neck thread, and heating the sleeve and thermally shrinking it circumferentially into tight engagement with the plug and with the neck and neck thread. The sleeve can be first fitted around the plug and then shrunk over the plug, after which the plug and sleeve are fitted together to the recipient, whereupon the sleeve is shrunk over the neck. Alternately the plug is fitted to the neck, then at the same time the sleeve is fitted around the plug and around the neck, and then the sleeve is heated to shrink it onto the plug and neck at the same time.

Abstract: A recipient having an axially upwardly open neck formed with at least one radially projecting neck thread is capped by fitting a circumferentially thermally shrinkable sleeve around a plug, fitting the plug into the open neck to block same, fitting the sleeve also around the neck over the neck thread, and heating the sleeve and thermally shrinking it circumferentially into tight engagement with the plug and with the neck and neck thread. The sleeve can be first fitted around the plug and then shrunk over the plug, after which the plug and sleeve are fitted together to the recipient, whereupon the sleeve is shrunk over the neck. Alternately the plug is fitted to the neck, then at the same time the sleeve is fitted around the plug and around the neck, and then the sleeve is heated to shrink it onto the plug and neck at the same time.