Force carbonation vs. Bottle conditioning!

It is clear that good carbonation is essential to producing a high-quality beer since it enriches the flavors and also provides the beer with a pleasant texture (organoleptically speaking).

But as a homebrewer, what method should you go for, bottle conditioning or forced carbonation?

In this article, I will tell you everything you need to know about the different carbonation methods, how to carbonate your beer using one of them, what to avoid doing in order to get the best results, and more!

So, what is the difference between natural (bottle conditioning) and forced carbonation? During bottle conditioning, CO2 is generated through the action of the yeast cells consuming the sugars and creating CO2, whereas in forced carbonation, carbon dioxide is mixed into the beer by force, hence the name, thus incorporating it into the liquid. The latter method has the advantage of being faster but also more expensive.

First and foremost, let’s take a closer look at what exactly carbonation is:

What is Carbonation?

Carbonation is the process that occurs when CO2 is mixed with the already fermented beer and, depending on factors such as temperature and CO2 pressure, the level of carbonation will be higher or lower.

The level of carbonation sought is not always the same as it depends on the style of beer.

There are two methods of carbonating beer: the natural or bottle conditioning method, and the forced carbonation method.

Let us look at each of them in more detail:

Bottle Conditioning

When bottle conditioning, what we do is add some sort of fermentable sugar to the beer so that the yeast can consume it to generate CO2, usually white sugar, dextrose, etc., but it can also be wort, honey, or any other fermentable.

Bottle conditioned beer

Note: In some cases, a very small quantity of yeast is added as well, but this is only done if the beer was filtered beforehand.

Once the sugar is added, the bottle is filled and then closed, and in this way, we retain the carbon dioxide produced by the yeast cells (when they consume these new sugars that we introduced) since it can’t get out of the bottle and ends up mixing with the beer, carbonating it.

As for the containers we can use to carbonate beer go, it can be done in kegs, cans, or in bottles.

Bottle carbonation using a Primer

Priming is basically the method by which CO2 is generated inside the bottle as a product of fermentation. This CO2 cannot escape and is incorporated into the liquid inside the hermetically sealed bottle.

When the container is filled, the previously prepared primer (and yeast, unless the beer is not filtered) is added, then it is covered and fermentation is completed in a closed container, resulting in carbonation.

Can a keg be carbonated naturally?

Of course it can, and this method is carried out in the exact same way as it’s done when using bottles.

The finished beer is poured into the keg (being careful not to oxygenate too much), then the sugar we are going to use is added. Once this is done, it is recommended to leave it for 7 to 10 days to have a properly carbonated beer.

Note: Generally speaking, it’s advisable to add the primer first to the keg and then pour the beer on top of it since this helps it to thoroughly mix in.

How to make and use the Priming Solution

To make the primer correctly you need to boil approximately 300 mL of water mixed with the sugar we are going to use for the whole batch we want to carbonate (between 5 and 8 grams of sugar per liter of beer depending on the style). 

If you’re using a Keg to condition and carbonate your beer it’s best if you pour the primer into the keg first and then pour the beer on top of it (no need cool the priming solution here since the keg will cool it for you in no time).

In the case of bottles, the proportion you put into each one should be carefully calculated since, in the case of adding too much of the priming solution, you could end up getting under- and over-carbonated beers (over-carbonated beers could even explode, so be careful!).

How to make the Primer:

  1. In a saucepan add 300 milliliters of water and start heating it.
  2. While the water is heating up, put in about 5 to 8 grams of sugar per liter of beer.
  3. Let it boil for 2 or 3 minutes, stirring occasionally.
  4. Remove it from the fire and pour it into the fermenter or bottles without cooling if this is done before transferring the beer (if you’re pouring it on top of the beer, let it cool first).
  5. Bottle the beer and let it sit at room temperature for 7 to 10 days.


  • Affordable since we only need sugar.
  • No other equipment is required, such as pumps, etc.
  • Reduces oxygen pick-up due to the action of the yeast inside the container (it consumes it during fermentation).


  • It can modify the flavor of the beer.
  • Leaves sediment at the bottom of the container.
  • If sugar amounts are miscalculated, it is possible for the container to explode, or in the best case, to produce excessive carbonation.
  • It takes a long time to achieve balanced carbonation (7 to 10 days minimum).

Forced Carbonation (using CO2)

To understand how carbonation works, we have to consider that the carbonation of any beverage is based upon the balance between the gas that is being dissolved, the gas pressure on the liquid, and the temperature of the liquid. 

The efficiency of this process depends on:

  • Bubble size: the smaller the bubble introduced, the greater the surface area of gas exposed to the liquid, therefore carbonation will occur faster.
  • Exposure time to the liquid: if not given enough exposure time, much of the CO2 will be lost without dissolving.
  • Pressure: it is extremely important that the pressure is kept at a constant so that the CO2 can dissolve into the beer.
  • Temperature: the lower the temperature, the shorter the time it takes for the CO2 to dissolve.

How to carbonate beer using CO2

When doing this, we carbonate our beer by keeping it at a constant temperature and subjecting it to a consistent CO2 pressure, so that it dissolves in the beer until it reaches the ideal carbonation point that we want

This is a process that takes some time (not as long as carbonating using bottle conditioning) and is faster the lower the temperature of the beer is. Forced Carbonation is usually done inside the keg by connecting it to a CO2 tube.

By doing this and controlling the overall CO2 pressure inside the keg, we allow carbonation to take place.

This process can be accelerated by agitating or rolling the keg, which increases the rate at which the CO2 is allowed to dissolve in the liquid.

This process is more expensive than doing it naturally (carbonating using fermentable sugars) and can only be done in kegs or in steel fermentation vessels.


  • Easy to get the amount of carbonation right.
  • Does not leave any sediments.
  • Does not modify the flavor.
  • Faster than natural fermentation.


  • Costly.
  • Requires a steel barrel and CO2 tube with a regulator.
  • Does not reduce the oxygen level inside the container.

At what pressure should the Keg be at?

To answer this question, it is essential to take into account two other variables: the temperature of the beer and the volumes of dissolved CO2 we want to reach.

The simplest and most convenient answer is to set the regulator to 1 BAR (15 psi) of pressure and keep the keg refrigerated at a constant 5 degrees Celsius.

After approximately 2 days, our beer should have about 2.5 volumes of dissolved CO2 (a more than acceptable value for the vast majority of styles).

Is it possible to do forced carbonation and then bottle?

Yes, it is possible. A tip in the case of choosing this method is to do it with the beer at the lowest temperature possible, since this way we stabilize the liquid and avoid losing carbonation levels.

Another recommendation is to raise the levels of dissolved CO2 before bottling since, during the process, some carbonation may be lost.

Bottle Conditioning vs Forced Carbonation

If we only focus on the final product, forced carbonation is definitely better because we get a cleaner and more stable beer, although for us homebrewers this is necessarily not the case. 

In the homebrewer’s world, the most convenient method to choose is bottle conditioning or fermenting beer in a keg using sugar, since the cost is much lower and, if we take the necessary precautions, the level of carbonation will be identical.

It should also be taken into account that bottle conditioning, by going through a second fermentation process, absorbs much of the oxygen that may have been introduced into the bottle during filling, which increases its shelf life.

Is there a difference in taste?

Undoubtedly yes, the sediment in suspension produces unpleasant flavors generated by the yeast, and in extreme cases, a wet cardboard or green apple flavor could be produced if there is excess oxigen in the bottle.

Although this can be reduced to a minimum by judiciously applying the techniques we have seen throughout this article.

In addition to this, the carbonation of one method vs the other is also slightly different: Force carbonated beer loses most of the CO2 quite quickly once served, which doesn’t seem to be the case with beer that was carbonated naturally.

Try it out: pour yourself a glass of force carbonated beer as well as one that was bottle conditioned, and once you’re halfway done with the beer, one will have lost more carbonation than the other.

Are there any risks involved?

Yes, both methods come with some risks. A few things can go wrong, but if we pay attention to what we are doing, there shouldn’t be any problems.

By bottle conditioning, the main risk is associated with exploding bottles. Yes, beer bombs. If you put more sugar (or whatever you are using for the secondary fermentation) inside the bottle, it could explode.

This happens because the fermentation inside the bottle generates way more pressure than the bottle or caps can take. 

With forced carbonation, the risks are also pressure-related: Poorly sealed kegs or hoses can lead to CO2 leaks, but too much pressure inside the keg can be dangerous as well. 

Bottle Conditioning Pros

  • Oxidation is not as much of a problem.
  • Cheaper, less equipment needed.
  • Possibility to add more flavors (honey, brown sugar, etc.)

Bottle Conditioning Cons

  • Cloudy beer, lots of sediment
  • Higher risks of inconsistent carbonation.
  • Takes longer (up to three weeks for lagers).

Force Carbonation Pros

  • Quicker (especially if you roll or shake the keg)
  • More accurate carbonation, with the regulator and a fridge you can know the exact level of carbonation.
  • Beer with less sediment.

Force Carbonation Cons

  • More expensive, more room and equipment needed.
  • Need extra equipment to bottle.

What methods do commercial breweries use?

Both methods are used by commercial breweries. Many Belgian breweries bottle condition their beers (Orval, Lambic beers), as well as some Weissbier breweries in Germany.

A lot of small to medium-scale craft breweries around the world force carbonate their beers, either in the tank or once in the keg.

And something that is commonly used for larger breweries is natural carbonation in a big Lagering tank.


As with most brewing processes, it all depends on how much we are willing to spend and what criteria we apply.

Budget, beer style, brewing experience, and time, are some of the factors that will make us decide on one carbonation method or the other. Of course, you can do both if you have the time and equipment to do so, and then compare the results.

This article intends to provide you with all the necessary tools so that you can conclude for yourselves which is the best option.

Frequently Asked Questions

Can beer carbonate if sugar is not added? Yes indeed, but in no case is this favorable as it is mainly due to incomplete primary fermentation or, in the worst case, due to severe contamination.

At what PSI should I do the forced carbonation? It is recommended to maintain a pressure of between 15 and 20 psi depending on the temperature of the beer (preferably between 5 and 8 degrees).

Can I force carbonate my beer at room temperature? Yes, but it is not recommended. You will need a lot of pressure in the keg. It is always recommended to Force carbonate beer when it’s cold, at least at 4 or 5 °C (39 to 41°F).

How much primer can I use? That will depend on what you are using as a primer and the levels of CO2 that you want in the finished beer. It’s not the same to prime with table sugar as it is with honey. Fortunately, there are a few priming calculators that we can use to get the accurate amounts.

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