As a proud owner of a Jewish mother, a Jewish Grandmother, and now a little baby, I am quite accustom to gushing. It usually starts off lightly and then bursts into a full force stream of compliments about how cute/smart/funny/alert/strong/perfect the baby is, and how she looks like me (ok, so they're not all compliments... ) And that's great when it comes to my kid. But when it comes to my beer I prefer it to, well, stay in the bottle.
Case in point: I have a few bottles of beer that I brewed with a fellow homebrewer (Let's call him "P.I.C." for "Partner in crime") back in November. It was a Belgian Triple that was brewed on PIC's system, bottled by him (without me present), and was lagered in his fridge for a month before it was delivered into my waiting hands sometimes in early December. I got thirty bottles that promptly went into the basement of my building, where the temperature at this time of year is around 12 degrees C. So far so good.
I drank a couple of bottles, and they were good, but they could be better. A bit of research taught me that a Tripple should be aged for a couple of months to achieve peek flavor, and so I left them in the dark, cold basement to age slowly, and for the past month I've been slowly going through them.
But it turns out that I'm not the only thing going through them. It was slow at first: a feeling that the beer is a touch over carbonated. Then a foam that rose out the bottle when I first opened it. Then it got to the point where I'd have to have a glass ready to pour the beer into as soon as it was opened. And finally, a couple of days ago, I opened one of the bottles (very slowly, after cracking the cap open a couple of times to let the gas escape) and was treated to a full-force geyser out of the bottle. No doubt, it had a gushing problem.
Why do bottles gush? Well, in the simplest terms, it's when there's too much pressure in the bottle. Since pressure is the result of fermentation, over-pressure is, loosely speaking, the result of over-fermentation. That is, there was more fermentable material in the bottled beer than was required to carbonate it. There are three main reasons for this:
1. The beer didn't finish fermenting before it was bottled, leading to residual sugars being fermented.
2. Too much priming sugar was added
3. The beer was infected with a bacteria or foreign wild yeast that can ferment sugars that ordinary beer yeast cannot.
The first case happens sometimes when cold-crashed beer gets warm again. The yeast wakes up, eats up the rest of the sugar, and presto! Gushing. If there's enough sugar, the bottles wont just gush, they'll explode.
The second case is self-explanatory. If you dump too much sugar in the beer before you bottle, you'll end up with too much bottled gas. This happens a lot with beer made from kits. Beginner brewers just dump all the sugar in without calculating what they actually need, and without realizing that often a kit comes with two or even three times as much sugar as necessary.
The third case is typically the result of poor sanitation somewhere a long the process. Typically, if the gushing is not limited to a bottle or two, but is consistent throughout a batch, the problem is in the bottling equipment, the racking equipment, or the fermenter. In other words, something that comes in contact with the entire volume of beer.
So what happened to the Tripple? Well, it's a bit of a mystery. On the one hand, PIC insists that his bottles didn't gush. On the other hand, he tends to drink his beer so green it's practically still wort. On the third hand, I know the guy, and he tends to pour priming sugar in by the cup-load. On the fourth hand, the slow progression of the process seems to indicate infection. On the fifth hand, this is not the only beer he had bottled that I've ended up wearing rather than drinking, so that points to something in his process. And on the sixth hand, he claims it's all my imagination, and that it never happens to him.
I don't know what happened to the Belgian. To be safe, though, the next time I open a bottle, I'll do it in the tub. And take a video, just to prove I'm not imagining things...