Why are there 21 teeth on the beer bottle cap?


Speaking of beer, there is a very interesting phenomenon that everyone may have never noticed. That is, there are not more than 21 jagged teeth on the beer bottle caps, and the number of jagged teeth on the beer bottle caps of all brands is the same.

Before the tin beer bottle cap was invented, most of the bottle caps were wooden stoppers, but the wooden stopper was very troublesome when it was opened, and the beer itself had sufficient gas. If it could not be opened at once, the gas inside would slowly run away. Without sufficient foam, the taste of beer will naturally deteriorate. So people hope to find alternatives to wooden corks to quickly open the cap. At the end of the 19th century, the Englishman William Pat found that the sawtooth metal caps were more convenient to open. The only difference was that the tin caps he invented were 24 teeth. The appearance of the beer caps at that time was basically the same as what we saw today. , There are paper pads inside to prevent the beverage from contacting the metal. The 24-tooth bottle cap is patented and has been in use until the 1930s.

The development of industry saves manpower. The original manual capping gradually evolved into industrial capping. The 24-tooth cap was first pressed with a foot press, one by one, on the bottle mouth. After the automatic filling machine appeared, the bottle cap was put into a hose for automatic installation. However, during use, it was found that the 24-tooth bottle cap easily blocked the hose of the automatic filling machine, and this situation would not occur after changing the number of teeth to a single number, but a 23-tooth seal was found in the subsequent installation. Sex is not as good as 21 teeth, so the 21 tooth cover is still used today.

The beer bottle cap is designed with 21 serrations, which is not designed according to any principle, but the result obtained after people's experiments. And this experiment is actually related to the corkscrew.

As we all know, beer contains a lot of carbon dioxide, so there are two most basic requirements for bottle caps. One is better sealing. People like to drink beer in summer because it contains carbon dioxide. Carbon dioxide will be released soon after entering the body, taking away the heat inside the body and making people feel cool. And with the release of gas, it can also impact the inside of the mouth, stimulate the mouth, give a pleasant sense of stimulation, and bring out some bacteria. Therefore, when drinking beer, people like to drink in large sips, so that more carbon dioxide can be inhaled, which brings a comfortable taste, which is also a unique flavor of beer. Because beer contains a lot of carbon dioxide gas, it is necessary to consider how to open the beer bottle safely and conveniently in the design. After inventing a screwdriver suitable for opening bottle caps, and by constantly modifying the sawtooth, it was finally determined that the 21 tooth bottle cap is the easiest and safest when opening, so all the beer caps we see today are 21 serrations.

The second is to have a certain degree of bite, that is, the commonly known bottle cap should be firm. This means that the number of folds of each cap and the contact area of ​​the bottle mouth should be in a certain proportion to ensure that the contact surface of each fold can be larger, and the wavy seal on the outside of the bottle cap can increase friction and facilitate Open. And 21 teeth is the best choice to meet these two requirements.

The design of beer bottle caps has been recognized, and it is soon used in other beverage packaging, such as cola, sprite, sour plum soup and other bottled beverages.

Why are there 21 teeth on the beer bottle cap?
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