Cold Crashing Your Homebrewed Beer

Many people start home brewing for a number of reasons. Some take up the hobby as a bit of fun, others are unhappy with the price and choice of real ale or craft beer in pubs, and others start so they can make beer to suit their own styles and tastes.

In all cases the resulting beer doesn’t always match the appearance of the commercially produced, leaving lots of Home Brewers scratching their heads raising the question ‘Why can’t I get my beer to look so clear?’

This is where Cold Crashing comes in.

What is Cold Crashing

Cold Crashing is the process of lowering the temperature of your home brewed beer before bottling. Introducing cold temperatures encourages yeast, proteins and other solids (such as hop debris) that are suspended in the beer to clump together becoming heavy enough to eventually sink and form the trub at the bottom of the fermenter. This would otherwise be left behind, causing a cloudy finish to your beer.

The result of the cold crash helps give your beer a cleaner, crisper and more colorful finish. The hazy look doesn’t usually affect the beers flavor but its presence is considered by most as a flaw, especially within the competition scene.

So How & When Should I Cold Crash?

If you cold crash 2-3 days before bottling once your final gravity is reached, this should provide enough time for the technique to work. This also allows you plenty of time for any dry hopping (which should be done prior to cold crashing, generally between 7-10 days prior to bottling) and for the yeast to clean up some fermentation by-products.

The ideal temperature you should reach is 35-40°F (2-4°C approximately). A temperature controlled fridge large enough to hold your fermenter is the most efficient way to achieve this.

What happens if I don’t have a fridge?

Cold Crashing via ice bathMany home brewers that start out don’t have the luxury of either an empty & large enough fridge or one that is solely dedicated to their home brewing needs, so there are alternative methods that can be implemented.

The first alternative is to wrap a large wet towel around the fermenter and sit it in a water bath (big tub) filled with ice/ice packs making sure that the edges of the towel are in the water. Replenishing with fresh ice or packs every 12 hours or so. The main problem with this, except having a large wet towel in the open for a number of days, is the fact that you’ll mainly be cooling the bottom of the fermenter and the temperature won’t really circulate to the top.

Another similar solution is to have a cooler (cool box or bag) that is big enough to fit the fermenter, take 6-8 ice packs or a lot of ice and place around the fermenter. If you did this in the evening/night time switch the ice packs for fresh ones in the morning. This probably wont drop the temperature as low as a fridge but you’ll find it will drop your beer by 10-15 degrees to about 50°F (10°C). Again keep switching ice packs for 3 days and then bottle.


I did this with my latest brew, an American Pale Ale, however I wrapped a beach towel around the fermenter rather than placed it in a cooler. With ice packs sandwiched between the towel and fermenter I managed to get the temperature to around 53°F (12°C) in 2 days, with the addition of bottle conditioning I’m very happy with the results.

If you are to cold crash and bottle condition your brew you may find that you need to allow extra time to condition, as there would be less yeast present to carbonate the bottles.

Using Additives?

There are a number of additives that can help contribute to a clearer finish in your beer, fining agents such as Irish moss or whirlfloc, which can be added to the boil with 10 minutes left.

Finings Banner2

Gelatin can be used post fermentation and goes hand in hand with cold crashing to help things even further. Don't boil the gelatin. Instead, boil 1 cup of water by itself. Take off the heat for a minute or two then whisk in 1 packet of unflavored gelatin. Then add that to your fermenter. You may notice some improvement in 24 hrs, but allow for the same amount of time that you would if you cold crash (2-3 days).

Clear beer_web

Time for bottling

When its time to bottle your brew that you’ve patiently looked after and been waiting for, make sure you place the siphon above the trub to avoid sucking up everything you have tried to remove.

Damian Brann was born in the 80s, and raised in the 90s. He's a video game hobbyist, and a lover of geek & pop culture. He's a home brewer and runs His favorite beer St Austell's Proper Job.

written by Damian Brann

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20 comments on “Cold Crashing Your Homebrewed Beer”

  • Can we cold crash and gelatin and filter the beer ?

    • David Doucette

      You can, but that may be a bit overkill. If you have access to a decent filter, you shouldn't need to cold crash & use gelatin in addition.

      • Don't tell him that. Yes, by all means gelatin and CC your beer. Nothing wrong with a crystal clear brew.

        • Yes, by all means use gelatin and cold crash. I use this with wine and beer. Gelatin also reacts with tannins and removes some of them as well.

        • Clarity and taste are very subjective. If you must have a crystal clear brew, by all means use what you must. For me, taste is 1st, then clarity is a bonus. Brew on my friend!

  • TheBarefootBrewer March 11, 2016 at 10:50 am

    One thing to note about cold crashing in the fermenter is the pressure change between temperatures.
    I had 2 carboys suck the airlock dry and expose my beer to oxygen because as the temp changes, the pressure inside the carboy contracts and sucks in whatever was in the airlock. Now a bit of star san isn't going to hurt a full batch of beer but the air it's exposed to once it's gone is.
    To remedy this, I just make sure to either just start with- or switch to for crashing- an extra long blowoff tube. By that point, the air in the tube, blocked by sanitizer at the end, will all be co2 emitted from the brew and harmless to it's its health.

    • Misterchipster August 4, 2016 at 2:51 pm

      I beg to differ on this, when a carboy is left relatively undisturbed the heavy C02 "settles" to the bottom of the container. This blanket effect on top of your beer protects your beer even with the introduction of a small amount of air drawn through the airlock, because it is not and heavy as the CO2 the air remains "on top" of the CO2 blanket. Caution should be used to not disturb the carboy to avoid "stirring" the air into the CO2 blanket. Have seen this work on commercial food applications just fine.

    • The amount of air pulled in wont make a difference. There's still a CO2 blanket over the beer that hasn't gone anywhere. I wouldn't worry too much about that

  • Can you cold crash before kegging?

    • David Doucette

      Yes. Kegging also acts as a cold crash, if your dip tub is high enough, the particulates in your beer will drop below the dip tube. But no harm will be done if you cold crash, and then keg it.

  • An ice block frozen in a bunt cake pan fits perfectly over the top of a carboy. Place an old t - shirt over the carboy, followed by your doughnut ice, and you're off to the races!

  • Can you cold crash a fruit beer? Fruit added to secondary

  • Will there be enough yeast in suspension to carbonate for bottling?
    I've also seen picture of fermenters caved in from cold crashing. How do you prevent this and how do you prevent oxygen exposure after the airlock is sucked dry?

  • I've been brewing since 2004 ish. Can't remember the book I read on Brewing when I started, but it had a few pages on this. So I've been crash cooling as routine from day one. Now I did have a dedicated refrigerator for this. I know a lot of people don't. But the effect of a beer crashed cooled is night and day clarity. On a regular beer say IPA , on avg I'm 7-10 day fermentation, followed by 7 day dry hop, followed with 7 day crash. I mostly keg so with temp at 34° I'm right there. I always keep my eyes open for people getting rid of refrigerators. They can't see the uses we can.

  • Has anyone used dry ice? Any Problems using dry ice?

  • Won't using a floculent like irish moss do the same thing?

  • Use a plate filter. Its made in canada a one or three micron filter will do just fine. Don't have to do all that work.

  • First, I suspect that lowering temperature moderately slowly is preferable to a sudden drop. Yeast can release off flavors when stressed by sudden temperature changes.

    Second, gelatin works best in beer that is already very cold. Cool if to within a couple of degrees of freezing, then add gelatin. Two or three days later the beer will be brilliantly clear.

  • My question is what happens after the cold crash. Can I immediately bottle the beer, or do I bring it up to room temperature and then bottle? If I need to being it up to room temperature, do I need to step up the temp slowly over a few days or take it out and let it come up to room temp over a few hours? Perhaps it does not make a difference?

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