There’s a debate that crops up from time to time in the wine community regarding the best way to seal a bottle. For centuries, wine was sealed with a round bit of cork crammed into the neck of the bottle. What began as necessity based on the limits of technology of the day became a cherished tradition. Now there are a variety of ways to seal a bottle of wine from corks made of hard rubber to screw-cap tops. Most of these offer a better and more stable alternatives to the traditional cork but most wine is still sealed with cork. Corks are traditional and trusted, rubber corks are seen as questionable and screw-caps are down-right dubious.
To a lesser degree, there’s a similar question that plagues beer lovers, is the pop-top better than the screw top. Interestingly, the screw-top moves in exactly the opposite direction in beer than it does in wine. It doesn’t provide as good or stable of a seal as the pop-top cap, the older sealing method.
The cap does two things. It seals out the air which would spoil the beer in time. It also seals in the pressure of the carbonated beer which is why it hisses when you open it. The pressure is greater inside the bottle than in the atmosphere. The hissing is the compressed gas rushing out of the bottle.
In order to do these things, the cap must hold on as tightly as possible to the lip of the bottle. The pop-top style cap has an uninterrupted lip to crimp around. This tight of a hold plus the rubbery lining on the inside of the cap forms a very reliable seal on the bottle.
Bottles with threads instead of the fat, uninterrupted lip provide a less reliable seal. There are simply more spots around the inside of the cap that air or infecting bacteria can get in or out.
The reason that wine bottles with screw-tops caps provide a better seal while beer bottles with screw-top caps form less reliable seals has to do with the way that the bottles are processed on the bottling line. When brewers switch to screw-top caps, they stick with the same machinery and, basically, the same caps. The caps are placed on the bottle top and pressure applied to the edges until they crimp around the neck of the bottle. The cap has to do the same job with a less reliable bottle neck. Screw-top wine bottles, on the other had, allot much more room to the threads. The metal tops is perforated below the threads which allows a long collar that can reliably hold onto the bottle top. Also, most wine is still so the cap isn’t fighting internal pressure the same way that a beer bottle is.