For the second time I have a batch that ended up way over-carbonated after about four weeks in the bottle. That could be an indication that I used too much priming sugar, but could it also indicate that I bottled too soon when the fermentation wasn’t quite done?
Yes. Please provide some more info. How did you determine fermentation was done. How much priming sugar did you use, how much beer did you have in the bottling bucket. Etc…
Make sure you know exactly how much you are packaging. This is important when calculating the final carb volume. If you calculate for 5 gallons but are leaving half a gallon of yeast and trub at the bottom of your fermenter and only end up bottling 4.5 gallons, you are going to be overcarbing.
Yup, this was my problem for some of my early batches. As a result, they would hit a good carb level after 3 or 4 weeks, but then keep on carbonating past that and I’d lose a third of the bottle to foam every time I opened one. Now, if anything, I intentionally undercarb a bit. Generally, I shoot for the 2.2 vol range, no matter the style and I haven’t had any problems since. It can take a bit longer for some batches to carb up, but once they do you can use a good aggressive pour and get a nice head without worrying about a bunch of foam.
Also, make sure your priming solution is mixed in. It will get reasonably well mixed if you just put it in the bottling bucket and rack the beer on top of it, but I always give it a gentle stir (no splashing) with a sanitized spoon to make sure the priming sugar is equally distributed.
I had an issue with some infection that would turn my bottles into gushers. I bleached everything I had and replaced all my tubing and plastic bits and that did help and was rather cost effective. Some infection, when it is in the early stages, doesn’t have much of a flavor or odor so you might miss it when bottling.