Gushers - when will they occur?

[Cody]

I'd like to find out what causes a gusher. Not just overcarbonation, but what level of carbonation. We've got specialty Belgian beers at 4.5-5 vols of CO2, we've got Champagne. What's the difference, here?

The impetus behind this is that I have a beer that I've gotten uneven carbonation on, my Funky Saison. Some bottles are perfect, some start gushing out the top as soon as you pop the cap and take 20-30 minutes to even become drinkable. What level of CO2 is this? I used normal bottles and have heard that these are only good to 3 vols of CO2, which seems to contradict what I'm seeing with these.

[Quin]

Will also depend on temperature and time for CO2 to get back into solution following a temperature change. A beer/champagne that "gushes" at 50°F may be fine at 32°F.

[Cody]

Yeah, I'm talking normal temperature straight out of the fridge, say 38-40°. After chilling for a few days for stabilization.

[spiderwrangler]

The gushing is also going to be dependent on head forming proteins, etc (possibly other stuff if it's due to infection). If it was just highly carbonated water, it wouldn't foam up...

[brewinhard]

Temperature of the stored and served beer as stated above. Most likely caused either by overpriming or infection.

[Cody]

I get the causes of overcarbonation and that it is overcarbonation that causes the beer to gush.

What I want to know is if I have a continuum of bottles with different priming levels from low to high, at which point will I start to see beer gushing?

Spider is starting to get to my question.

[spiderwrangler]

I really do think that the prolonged gushers are due to a lot more than just volume of CO2. My first beer was a gusher... it was also a delicious IPA, but we bottled it way early because we'd brewed and were ferementing at a friend's house and they were leaving the state for 3 weeks. I doubt the volume of CO2 was any higher than what you might get in a bottle of highly carbonated Belgian-style ale... we aren't talking bottle bombs here, just gushing. When you opened the cap, it would slowly start to foam up, and if you set the bottle in the sink, would probably foam for a good 15 min or so. I'd pour it out in a mixing bowl and drink it that way...
Gushing in my mind is due partly to the CO2, but the underlying causes are probably based more on availability of nucleation sites where the CO2 can come out of solution and form bubbles (like Diet Coke and Mentos), combined with the presence of proteins and other compounds that allow for the formation of the foam. I feel like residual unfermentable sugars would factor in here somewhere. I'm sure that at some high carbonation level, even with 'normal' levels of the other considerations, you would be able to determine how much CO2 is too much, but it would be dependent on the beer itself.

So I guess that's my Chris White answer... it depends.

Cheers.

[Cody]

Interesting. Kinda makes sense. When I first opened one, I poured it into my clean glass and the entire thing was pure foam, no liquid whatsoever. My FG for this was 0.998, so not many unfermented materials left over. On the other hand, your point about nucleation sites rings a bell. I seem to remember seeing a lot of stuff on the sides of the bottles, like a light dusting of yeast, but on the sides. I'll have to go through my bottles and check this theory. Maybe a cleaning is in order.