what is an airlock, and what does it do?
The key part of making a wine is the fermentation process. This is the part when the little yeast cells munch on the sugar in the wine mixture, kicking out alcohol and carbon dioxide. The alcohol is, of course, good. But the carbon dioxide is a gas. If you had a sealed container, and those yeast kept making more and more carbon dioxide, the container would blow up. That would be bad. On the other hand, you can’t just leave the top off the container. While that would let the carbon dioxide escape, it would also let lots of oxygen in. And oxygen isn’t a good thing to mix with wine – it turns it into vinegar. The answer is an airlock. The airlock lets the carbon dioxide escape. It also doesn’t let air enter easily. It’s not that it has to BLOCK air from coming in exactly. The carbon dioxide inside is under pressure and wants to get out. But the air outside isn’t actively trying to get in. Think of it as a bottle of soda. If you shook it up and then laid a piece of saran wrap on top of the
