If you’ve ever visited a nice beer bar, you may have noticed a small sink your bartender uses to rinse your beer glass before serving you. That sink looks like this:

It’s called a star sink, or a glass rinser. You press the glass rim down into the glass rinser, which shoots a mist into it. It looks super cool and it’s also an efficient way to prepare a beer serving glass. However, you might be asking yourself, “Why doesn’t the bar just prepare clean glasses beforehand? Why rinse them right before serving me my beer?” Well, the glass cleanser doesn’t give your glass a thorough cleaning. Rather, it’s used to blast away away lingering dish soap, or other crud that accumulates when you’ve left a glass out for awhile.

But this sink actually serves a greater purpose than just cleaning your glass.

When you rinse a beer glass, it becomes more slippery, and there’s less friction when beer fills it. This allows a more even, clean pour and a substantial, fragrant head. As we’ve established before, beer foam is actually a good thing, because it carries a great deal of your beer’s aromas, and smelling is half the fun. The other benefit of rinsing a beer glass is that the spritz can cool the glass down, because we know that pint glasses often have the tendency to prematurely heat your beer up.