Heat-shrunk threaded bottle cap

A method of capping a recipient having an axially upwardly open neck formed with at least one radially projecting neck screw thread, the method comprising the steps of:

• (a) fitting a circumferentially thermally shrinkable polyvinyl chloride sleeve around a plug having radially extending grooves;
• (b) fitting the plug into the open neck to block same;
• (c) fitting the sleeve also around the neck over the neck screw thread;
• (d) heating the sleeve and thermally shrinking the sleeve circumferentially into tight engagement with the grooves of the plug to rotationally lock the plug in the sleeve;
• and, separately from step (d),
• (e) heating the sleeve and thermally shrinking the sleeve circumferentially into tight engagement with the neck and into a threading engagement with the neck screw thread, wherein said sleeve may be repeatedly screwed onto and unscrewed from said neck screw thread.

A method of capping a recipient having an axially upwardly open neck formed with at least one radially projecting neck screw thread and an annular radially outwardly open groove, the method comprising the steps of:

• (a) fitting a circumferentially thermally shrinkable polyvinyl chloride sleeve, having an annular tear line in a lower region thereof, around a plug;
• (b) fitting the plug into the open neck to block same;
• (c) fitting the sleeve also around the neck over the neck screw thread so that the tear line is positioned slightly above the groove;
• (d) heating the sleeve and thermally shrinking the sleeve circumferentially into tight engagement with the plug;
• and
• (e) heating the sleeve below the tear line, and thermally shrinking the sleeve circumferentially, below the tear line, into tight engagement with the neck and into a threading engagement with the neck screw thread, wherein said sleeve may be repeatedly screwed onto and unscrewed from said neck screw thread.