Author: Marshall Schott
Of all that contributes to the goodness of beer and other adult beverages, I view carbonation as being one of the most important. While guidelines list “required” amounts of carbonation based on style, I’m of the camp who prefers nearly all of my beers to have a decent sparkle, to me it’s what adds that refreshing touch. The beautiful thing about brewing our own beer is that we get to choose the carbonation level we so desire! Want a petillant Pilsner or sparkling Stout? Go for it!
What I’ll be discussing here are the various carbonation methods I’ve used not only for beer, but sparkling cider, mead, and non-alcoholic soda. The focus of this article is on the more practical side of carbonation, what I’ve done over the years to achieve what it is I’m looking for, as this is the stuff most people seem to ask me about. Naturally, as someone who kegs, force carbonation methods are those I know best and will be discussed a bit more in depth, though I’ll briefly go over bottle conditioning since that’s where I cut my teeth and it’s the method many rely on today.
| FORCE CARBONATION |
If there’s one thing I hate about brewing, it’s bottling beer, even more than cleaning up. I get that some people find it relaxing or whatever, but I don’t, I loathe it. Thankfully, I discovered kegging when I did, as without it I’d certainly not be able to brew near as often as I do. I got my first kegerator about 6 years ago and found there were two popular options for force carbonation– set it and forget it or crank and shake. As I progressed as a kegger, I began to view these options as extremes, the bookends inside of which lay other, perhaps even better, methods. Nowadays, I choose the carbonation approach that best fits my schedule, rather than relying on a single method for every beer. I’ll go over all of these here, but first, a few things I keep consistent between batches:
- Every beer I make is cold crashed for 12-24 hours then fined with gelatin and left to sit another 12-48 hours prior to packaging.
- I only transfer the clearest beer to kegs and tend to leave about a quart in the fermentor.
- I only carbonate cold beer.
Set It And Forget It
The easiest force carbonation method there is involves placing your filled keg in the keezer/kegerator, attaching the gas to the proper post, then leaving it alone until the beer reaches your desired level of fizz. I’ve done this multiple times and have found it typically takes 10-14 days at 12 psi to achieve stable and enjoyable carbonation, certainly better than the 2-3 weeks required for bottle conditioning, but still a tad too long for my impatient 
tush. Perhaps the best thing about this method is that it reduces the risk of overcarbonation to nearly impossible. Also, this is where those snazzy force carbonation charts come in most handy– so long as you know your beer temp (whatever your regulator is set to) and the pressure of the CO2 on to your keg, you can produce a very predictable level of carbonation using this method.
Crank And Shake
Presumably developed by eager beavers sick of waiting for their beer to carbonate, the crank and shake method allows brewers to carbonate beer in under an hour. For the first few months of my kegging career, this was my method of choice because ain’t nobody fittin’ to wait a full week for bubbly beer! My approach involved cranking the CO2 to 30 psi and gently rolling the keg on my lap for precisely 10 minutes. The trade-off to this quick and dirty method is the increased risk of overcarbonation, which I certainly have experienced. Nothing like being excited to try your latest concoction only to be let down by a glass full of foam. Also, there’s something about agitating the beer so much that made me anxious, which is what ultimately led me to the method I use most often today.
Burst Carbonating
About 4 years ago, a friend of mine posed the idea of carbonating beer samples pulled from the fermentor with a SodaStream, typically used to make sparkling water and fruit juices via a burst of high pressure CO2. This got me thinking about ways I might utilize a similar approach when carbonating kegs of beer. Without doing any research, the next beer I kegged was hit with 30 psi for 24 hours after 
which I reduced it to my preferred serving pressure of 12 psi. The beer was somewhere around 75% carbonated, definitely enough to drink and enjoy, but it took another 3-4 days to reach peak.
This was the method I used for about a year, until I upgraded my standard manifold to a 4-way secondary regulator, a device that allows for independent control of the CO2 going to each keg. With this, I was able to carbonate and serve beer from different kegs, and so began my experimentation with higher pressure carbonation. What I found certainly isn’t groundbreaking and totally based on my subjective carbonation preferences. There is some simple science involved, pressure to the keg is inversely correlated with carbonation time, but there’s no good way to predict CO2 volume accurately. I’ve documented the time it’s taken 5 gallon batches of my beer to reach what I consider to be adequate levels of carbonation at different pressure settings, your mileage may vary:
| CO2 Pressure | LOW/MODERATE | HIGH |
| <15 psi | Use carbonation chart | Use carbonation chart |
| 30 psi | 16 hours | 48 hours |
| 35 psi | 14 hours | 34 hours |
| 40 psi | 12 hours | 30 hours |
| 45 psi | 10 hours | 26 hours |
| 50 psi | 8 hours | 24 hours |
Since time to carbonate is also a function of volume, smaller amounts of beer carbonate quicker, for example I’ve carbonated 2 gallons of 38°F beer at 50 psi in right about 5 hours. These days, the pressure I select is dependent on when I’ll be able to tend to the keg– if I package on a work night, I’ll set the gauge to 40 psi so that it’s ready when I’m home the next day, whereas for Saturday night kegging sessions I’ll take it up to 50 psi since I’ll be around Sunday morning to reduce the pressure.
| NATURAL CARBONATION |
Bottle conditioning is likely the most popular form of naturally carbonating beer where a fermentable sugar, usually dextrose (corn sugar), is dissolved into a solution that gets combined with the fermented beer in a bottling bucket before being transferred to bottles. The filled and sealed bottles are then placed in a relatively warm location for upwards of 3 weeks where the residual yeast in the beer consume the sugar, producing a small amount of alcohol and, more importantly, CO2 that gets dissolved into the beer. Voila, carbonation!
Besides the time it takes, the biggest bummer I can think of when it comes to carbonating naturally is when a beer comes out either too fizzy or not fizzy enough, which I’ve learned is usually the result of using improper amounts of priming sugar. Thankfully, sophisticated calculators are available that take into account various factors including beer style and type of sugar used, allowing brewers to dial in precisely the volume of CO2 they desire in their beer. Priming tabs/carbonation caps aren’t a bad option in a pinch, but I wouldn’t recommend relying on them for every beer.
For those who keg, natural carbonation is incredibly easy and works very well in my experience. While some sources recommend using the same amount of priming sugar you would when packaging in bottles, others suggest using 1/3 to 1/2 the amount of priming sugar when keg conditioning. I’ve done both a few times and there doesn’t seem to be all the much of a difference. At this point, my recommendation would be to use whatever the calculator suggests for bottle conditioning, which ought to ensure at least adequate carbonation, and in the event it gets too bubbly, you can always purge to fix.
| COMMON CARBONATION CONCERNS |
Will cold crashing leave enough yeast to naturally carbonate my beer?
Yes. A cold crashed beer will still carbonate. If you have the ability and you like packaging clearer beer, do it without worry, there’s still plenty of yeast in suspension to consume the priming sugar and produce CO2. If you’ve a beer that isn’t carbonating, it’s likely due to a poor seal or the temperature being a bit cool. Some people experience beers tend as taking a bit longer to carbonate as well.
Will fining with gelatin/Biofine/ClarityFerm leave enough yeast for natural carbonation?
Absolutely! Fining agents help to drop yeast out of suspension, but not nearly enough to make carbonating your beer an issue. In fact, some of the best bottle conditioned beer I’ve had was fined with gelatin prior to being packaged, and it was beautifully clear to boot!
Can I bottle condition a lager beer that spent a long time lagering?
Absolutely. If you’re concerned, which I’ve never been, you can always toss in some additional yeast while racking the beer from fermentor to bottling bucket, just try to make sure it’s well homogenized before packaging. I’ve heard of people having success with anywhere from half a pack of dry yeast to a full pack of liquid, but I’ve never done this, so do your research if choose to.
I used a priming sugar calculator and my beer is way too carbonated, what’s up?
Assuming you used the proper amount of priming sugar, the cause of “gushers” can likely be explained by one of two things. First, it’s possible you packaged your beer before it was done fermenting, meaning the yeast continued to ferment the residual sugars in addition to whatever else you added. The other cause, which I sadly think is responsible for the large majority of gushers, is contamination. The bottling process can leave the fermented beer more vulnerable to wild yeast and bacteria, many of which are capable of chowing down on sugars the brewers yeast left behind. A consequence of overcarbonated bottles is bottle bombs, which can lead to potentially tragic injuries, please exercise caution when opening or disposing of such bottles.
How can I fix overcarbonated beer?
Fixing overcarbonated beer in a keg is super easy, simple unhook the gas from the post and purge the keg of just enough pressure so that the lid does not become unseated– if you lube your o-rings regularly, it shouldn’t be a problem if you deplete the keg of all gas. Every 6-12 hours, steal a sample and purge the keg again if it’s still too carbonated. I’ve found it takes a few purges, 3-4 over the course of a couple days, to produce a noticeable decrease in carbonation. The nice thing about this method is your beer remains undisturbed, so there’s no impact on clarity, and untouched by oxygen. However, there are some who contend the constant purging may reduce the aromatic qualities of hop-forward styles. A quick and dirty method for those who don’t want to wait involved purging, giving the keg a bit of a shake to push our more CO2, purging again, then repeating this process until the carbonation is where you want it. Similar to the way the crank and shake method increases the risk of overcarbonation, this may lead to undercarbonated beer, plus it’ll require more time to settle afterwards.
For overcarbonated bottle conditioned, I’ve heard of some who’ve had success cracking the cap to relieve pressure a few days in a row, but that seems iffy to me, making the beer vulnerable to both oxidation and contaminants. If one is certain their overcarbonation is not due to a contaminant but some other component, I suppose this is might be worth a shot, I really can’t say since I’ve never done it and I’m inclined to dump anything that gushes.
My kegged beer has been on gas for awhile and it’s still flat, what’s the deal?
I’d bet cash money you’ve got a leak somewhere in your CO2 system. Having built multiple keezers for friends, I’ve learned there are a few main culprits when it comes to leaks, the most common of which is a real facepalmer– a loose connection between the primary CO2 regulator and tank. As tight as you might be able to get the nut with your hand, it’s likely not tight enough, thus I recommend using a crescent wrench or vise-grips to ensure a secure connection. It’s also important not to forget the washer that goes between the regulator and tank, I’ve used both nylon and fiber, they’re similarly effective.
That about covers it. If I left anything out, please don’t hesitate to ask in the comments section!
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