Why are all beer caps 21 gears?
One of the requirements of the cap is tightness, which means more pleats; at the same time, the cap is firm, which means that the amount of pleats can not be too much to ensure that each pleat has a larger surface area. 21 teeth are the best compromise between these two requirements.
These lids are made in accordance with the internationally accepted German standard DIN6099, to make sure all the lids are the same. This standard not only defines the diameter of the bottleneck, but also the shape of the edge of the bottle cap and the manufacturing material.
These lids are made in accordance with the internationally accepted German standard DIN6099, to make sure all the lids are the same. This standard not only defines the diameter of the bottleneck, but also the shape of the edge of the bottle cap and the manufacturing material. One of the requirements of the cap is tightness, which means more pleats; at the same time, the cap is firm, which means that the amount of pleats can not be too much to ensure that each pleat has a larger surface area. The 21 teeth are the best compromise between these two requirements.The invention of this wave shaped edge metal cap is William Petr. He found that the optimum number of teeth for the bottle top of the sealed gas drink was 24, and the patent for the steel mould was designed. The 24 fold cover became standard for many years. Around 1930, steel moulds were threatened by cheaper tinplate molds. If the new mold still uses 24 teeth, it can not apply for a patent, so it has been changed into 21 fold to avoid infringement on the original design. 21 fold number is the minimum number of teeth to avoid beverage leakage.
