New answers tagged over-carbonation
Gushing is a sign of over-priming. You can get over-priming from using too much priming sugar, bottling too early (before the yeast has finished) or from a wild yeast or bacteria that eats the remaining sugars and produces CO2. In my experience, I have had a half a dozen gushers and two (unintended) sour batches. I would argue that all my gushers were from ...
Tobias and Tallie are right, and there are other things to look for: As scum on top of the beer, or a ring around the neck is a nearly always from an infection (the other possible cause would be unusual ingredients, like cocoa butter from chocolate, but you would know that). Another thing that can cause gushing, without infection or over carbonation is ...
If you took a specific gravity reading before you bottled and were confident that it was at final gravity, de-gas a sample and take another gravity reading now. If it's the same, it's over-carbonated. If it's noticeably lower, then some other wild yeast or bacteria else has likely got a hold of it.
There should be a characteristic flavour if it's infected. Many bacterial infections will produce acid, so often infected beer is sour.
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