My fiancee and I have taken the massive undertaking of brewing as much beer for our wedding as we can, and it's been a really fun project- thus far. We've brewed numerous batches successfully, yet our most recent batches have caused us a lot of frustration.

We made some delicious pumpkin ales, and stored them in a rubber container, and after a few weeks they started exploding. We were actually moving from one apartment to another, and I guess the commotion built up some pressure in the bottles. In any case, our bottles that had been quiet for 6 weeks started exploding- 1 by 1- 5 of them over the course of as many hours.

We cleaned off the surviving bottles, refrigerated them until they calmed down, and waited a day or two before attempting to degas them. I assume that with all the sediment that we lost in the secondary (aprx. 1 gallon), the standard 5 ounces of priming sugar from our kit was too much for our reduced volume beer. Anyways, I degassed the bottles, (easing out excess gas, then tightening again), and thought the problem was solved.

I then put the old pumpkin beers in a 3 month old bin of octoberfests that had never had a problem. Another pumpkin beer had exploded, covering my Octoberfests. I stupidly waited 48 hours since I was so exhausted from all the other chores of moving, before cleaning up the mess in the rubber container. After rinsing off the surviving pumpkin ales, and the octoberfests, I realized that the caps (custom made- grog tag.com) were beginning to show a bit of rust. Right after finishing cleaning the old bottles, an Octoberfest exploded into oblivion 6 feet away from me. Fortunately, I was fine.... But now I'm trying to figure out how this pumpkin ale chaos has affected my perfectly fine Octoberfests... I assume that my caps had corroded, and in the 48 hours I left them untouched, an infection ocurred that built up the pressure in the Octoberfests.

It's like a zombie appocolypse- my bad beers are now affecting my good ones!

So two questions:

1.) What are your thoughts on my theory about the original cause of the exploding? Using 5 ounces of sugar on 4 gallons of beer before bottling (again, this is due to the reduced volume from the high sediment). Should I use less sugar for the reduced volume? Should I add water to the beer to bring it up to 5 gallons again? For the record, we used the hydrometer and confirmed fermentation was done before bottling.

2.) Are the octoberfests exploding from the pressure increasing in the storage container as they explode one by one? Or are the octoberfests exploding from infection due to rusted caps?

In any case, I created an account here moments after this debacle occured with the octoberfests, and before finishing this post- another exploded in the container. I think I'm tossing this whole batch, for safety. But I don't want this to happen again. Beware of zombies.


  • 1. you can use pre-measured sugar tablets when bottling. This way you only have the exact amount of sugar required.
    – DaFi4
    Sep 6, 2016 at 7:54
  • 1. also, if you have less beer, then you need less sugar
    – DaFi4
    Sep 6, 2016 at 7:55
  • 2. maybe it got warmer over there, waking up something in the bottles
    – DaFi4
    Sep 6, 2016 at 7:56
  • you can get a cornelius keg and pour all the beer into it. serve it from the keg. The keg wont explode.
    – DaFi4
    Sep 6, 2016 at 7:56
  • 1
    What was your criteria used to determine fermentation was done when using your hydrometer? Stable SG? Are you sure you reached the true finishing gravity. Its possible to stall out a few points high. Take a couple readings and think because its stable its done. When bottling you pick up a bit more oxygen, the yeast can become reactivated and they finish the job on their way to the true expect FG.
    – brewchez
    Sep 6, 2016 at 11:31

2 Answers 2


A 25% increase in priming sugar really shouldn't do this. 5oz corn sugar in 4 gallons will put 3.2 volumes of c02. 4oz = 2.8 volumes.

3.2 volumes is within tolerance of a normal bottle. But most commercial beers will use a thicker champagne style bottle when more than 3 volumes are expected.

Its possible there was been more fermentables available to the yeast than ecpected from under attenuation in fermentation. However usually if this is the case the yeast has given up already and priming takes a long time if it even happens at all even with easily fermentable corn sugar.

The more likely senerio is that a wild yeast was introduced at bottling. Wild yeasts will consume sugars that brewer yeasts usually ignore so they will produce more carbonation. Usually the culprit for gusher infections.

As for the rusted caps. The inner liner should be ok and not effect the beer. You may be able like you said to get them very cold and try to degas and recap them. But is obviously risky if they are exploding. Use your own discretion.


You do need to be more careful about the sugar to beer ratio. I would think that could be a big part of the issue. However, if some of your oktoberfest beers are starting to go too then I suspect your fermentation was not as complete as you think. And even more realistic is that you have gotten a microbial contamination that has started to ferment out some of the non-fermentables in the the beers. They are overcarbonating due to that reason.

Seeing how its happening in two different batches, two different recipes; I'd suspect that's the real issue here. I don't think the rusted caps are the issue. They are exploding which means they are holding pressure. A contaminant would not be getting in there with sealed caps. The contamination happened somewhere in your process. (Or despite your measurements the beers were not truly done fermenting. see my comment on your question.)

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