The crown cork was patented by William Painter on February 2, 1892 (U.S. Patent 468,258). It had 24 teeth[citation needed] and a cork seal with a paper backing to prevent contact between the contents and the metal cap. The current version has 21 teeth. To open these bottles, a bottle opener is generally used.
The height of the crown cap was reduced and specified in the German standard DIN 6099 in the 1960s. This also defined the "twist-off" crown cap, now used in the United States, Canada, and Australia. This cap is pressed around screw threads instead of a flange, and can be removed by twisting the cap by hand, eliminating the need for an opener.
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