Since I started brewing again I've been using one-gallon kegs, but when I did a quick batch of Northern Brewery's Festivus Miracle a few weeks ago I bottled in swing-top bottles thinking I'd share with neighbors for the holidays.

Well, not only did it not carbonate, but I wound up very much not liking the beer anyway, so it got dumped. No great loss, and I'll be doing a Great Lakes Christmas Ale clone later this week for which I have high hopes.

The thing that irritated me more than the taste of the beer was the fact that it didn't carbonate. I used carbonation drops, which I've used a lot in the past and never had an issue, but since I'm planning on bottling some of the next Christmas Ale both to share and to potentially take to a homebrew club in January, I figured I better figure out my bottling situation because there is nothing more disappointing than waiting for a beer to finish bottle conditioning only to find it didn't carbonate.

A couple of years ago I had another batch (also a holiday ale, coincidentally) that didn't carbonate in the bottle and I was able to rescue it using Lallemand CBC-1 after the fact, which was a bit of a hassle. I suppose if I wanted to guarantee carbonation in the bottle I could pre-emptively make CBC-1 part of the bottling process to begin with but I also don't want bottle bombs, so ... this is why kegging wins on this point.

But, certainly for beers that need to age for a bit like high-gravity beers, bourbon barrel whatever, bottling is a great way to do so I got to thinking it'd be good to have a solid bottling process that removes as much chance from the equation as can be removed.

Carbonation Failure Theories

The couple of other times in the past I've had bottle-conditioned beers fail to carbonate, the first was a high-ABV bourbon and oak infused stout (pushing 10%), and the other was the aforementioned holiday ale that wasn't particularly high ABV (maybe 6.5% if I remember correctly), but it had cherries and honey in the mix.

In both cases, my best guess there is I pitched enough yeast to have it ferment, but maybe there simply wasn't enough residual yeast to eat the priming sugar and carbonate the beer.

The other potential cause in the case of the bourbon stout is the bottles themselves. I used swing-top bottles and perhaps they weren't fully sealed and the carbonation escaped as it was being generated. I don't believe the gaskets themselves were the issue since they were brand-new at the time of that batch, but it's another potential cause of failure.

In the case of the holiday ale I actually used 500 ml PET bottles so the bottle and lids weren't the issue; my best guess there is lack of residual and/or tired yeast due to the inclusion of fruit and honey.

It's also entirely possible I didn't wait long enough, but I kept bottles of the bourbon stout around for 2-3 months and while the flavor was quite good, the carbonation just never happened.

Lastly, two other things crossed my mind as potential issues:

1. I cold crash my batches, usually for 48 hours. Everything I've read indicates this does not negatively impact bottle carbonation and that you just have to wait a bit longer for the yeast to become re-activated, but the potential impact of cold crashing crossed my mind.
2. The use of carbonation drops versus table sugar or some other kind of sugar. When I was brewing quite a bit a couple of years go before taking a break while working on the new brewing space I used carb drops nearly exclusively and didn't have any issues other than with the couple of batches I mentioned, but it's another variable.

To summarize the theories:

1. Not enough residual yeast to carbonate
2. Bad gaskets or seal on flip-top bottles
3. Didn't wait long enough
4. Carb drops don't work as well as table sugar

So, let's set up this experiment and see what we can learn.

The Sacrificial Batch

For the purposes of this experiment I happened to have a second batch of this year's Learn to Homebrew Day recipe. I made the first batch using RO water and some additions, and for the second batch I used tap water and added 1/4 campden tablet. My tap water is pretty noticeably chlorinated when it's not filtered, so I was curious to give this a shot and see what the differences are between two otherwise identical batches.

When the tap water batch was done fermenting I thought I'd potentially sacrifice it as part of the experiment to hopefully get to the bottom of potential carbonation issues when bottle conditioning.

The Experiment

To test my various theories, I decided to cold crash for 48 hours and bottle as follows:

I also replaced the gaskets on the swing-top bottles with new silicone gaskets to remove the possibility of old/worn gaskets being the issue.

I'm going to let all the bottles condition at 68 degrees F for a full two weeks before chilling a couple to see where things stand.

Hate to end on a teaser, but check back in a couple of weeks for the preliminary results of both this experiment, and the result of the taste test between RO water with additions versus tap water with campden!

(Yeah, I know, terrible scientific method here with changing multiple variables and trying to squeeze multiple things into one experiment. I do what I can.)