How to Cold Crash Your Homebrew

Cold crashing is a tried-and-true way to clear up beer that involves no seaweed or fish guts whatsoever, just gravity and a cold nap. Here’s how to do it.

Dave Carpenter Oct 18, 2016 - 4 min read

How to Cold Crash Your Homebrew Primary Image

Brewers have a language all their own, and to the uninitiated, a conversation between two beer makers sounds like a bunch of gobbledygook.

Brewer 1: My beer hasn’t dropped bright yet.
Brewer 2: Did you remember kettle finings?
Brewer 1: Oh, no, I completely forgot! Just went straight to knockout and then whirlpool.
Brewer 2: You could try cold crashing.
Brewer 1: Great idea!
Brewer 2: Thanks! Let’s have a beer to celebrate!

Bright beer is beer that we mere mortals would simply describe as clear. As long as it’s not too dark (e.g., an imperial stout), you can peer right through it, with nary a hint of haze to be seen. Most commercial lagers are exceptionally bright because they’ve been filtered.

Kettle finings are substances such as Irish moss and Whirlfloc that we add to boiling wort to promote clarity, while cask finings such as isinglass and gelatin are added to fermented beer for the same reason. Cold crashing is a tried-and-true way to clear up beer that involves no seaweed or fish guts whatsoever, just gravity and a cold nap. Here’s how to do it.


You’ll need a cold space, ideally close to freezing, that can accommodate your bucket, carboy, keg, or other vessel (if you’re lucky enough to own a glycol-jacketed cylindroconical, the fermentor’s own cooling system obviates the need for such a space). In the winter, this might be an uninsulated garage or even the great outdoors. Just don’t let your beer freeze unless you’re making Eisbock!

Natural refrigeration is cheap, but mechanical is more consistent and perfect year-round. An old refrigerator is ideal because no temperature override is necessary. Just crank the temperature down as cold as it will go, place the beer inside, and wait. A chest freezer will require an external temperature controller to keep the temperature from dipping into ice territory. You’re aiming for just above freezing: lagering temperature, more or less.

Once your beer is in a suitably cold, dark space, it’s a waiting game. Flocculent yeast strains such as many from the British Isles may require barely a day or two. Bavarian Hefeweizen yeast and some of the more “powdery” Belgian strains might need a couple of weeks to truly drop bright.

Remember, your beer will continue to clarify in the keg or the bottle, so no need to aim for 100 percent transparency during cold crashing. In fact, if you bottle condition your beer, you do want enough residual yeast to ensure that those bottles carbonate up in a reasonable amount of time.

Beer clarity is as much about personal preference as anything else. Witbier is traditionally cloudy, and Oktoberfest is usually crystal clear. But it ultimately comes down to taste. If you like the beer you make, you’ve clearly brewed it right.

Learn to create crisp, cold-conditioned lagers at home with CB&B’s Introduction to Lagering online class. Sign up today!