Carbonation/Bottle Bombs

So I recently brewed a NB Scottish Wee Heavy. I went to London for two months for work, so brewed it right before leaving, let it ferment and then put in the basement for the duration of the two months. All readings indicating fermentation was done when i got back.

I then bottled the beer, added half a pack of US-05, four ounces of sugar and left in my closet. I recently went on vacation for a week and put the bottles in the closet. We did turn the central air off for the duration of the week and my guess is that temperatures got to about a high of 80.

I got back from vacation and found that two bottles had exploded (sorry, not a big mess, just a dried sticky puddle). I immediately put the batch in the fridge to prevent more bombs. I also noticed that some of the caps were pushed out (never seen this before).

My question is what could have caused this. I had tried two random ones and they tasted great, so no infection. I didn't think that the more yeast would have done it, bc I thought it was the amount of sugar that mattered. I put less than the called for amount of priming sugar when bottling.

I am down to two hypotheses:
1) the increase in temperature (would account for the caps)
2) only a couple bottles were infected (would not account for the caps)

Not sure about this...

Is adding extra yeast to the priming sugar unique for this style of beer? I've never heard of having to add extra yeast. There's usually plenty left over in the wort to carb. Not sure if it would account for the exploding bottles or not though.

Could have had just a couple infected bottles maybe.

I've had my beer carb in fairly hot rooms without exploding.

I would guess that adding the extra yeast was your problem. The only time to need to add more yeast is after lagering at cold temperatures which settles the yeast out of suspension and leaving very little in the bottling bucket. You had all the yeast you needed without adding more. You may also have had some residual sugars that the original yeast didn't take care of for whatever reason (ie stuck fermentation) and the fresh yeast went nuts. Just some ideas but I'm no expert.

mrduna01 said:

I would guess that adding the extra yeast was your problem. The only time to need to add more yeast is after lagering at cold temperatures which settles the yeast out of suspension and leaving very little in the bottling bucket. You had all the yeast you needed without adding more. You may also have had some residual sugars that the original yeast didn't take care of for whatever reason (ie stuck fermentation) and the fresh yeast went nuts. Just some ideas but I'm no expert.

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+1 probably hit this on the head.

mrduna01 said:

I would guess that adding the extra yeast was your problem. The only time to need to add more yeast is after lagering at cold temperatures which settles the yeast out of suspension and leaving very little in the bottling bucket. You had all the yeast you needed without adding more. You may also have had some residual sugars that the original yeast didn't take care of for whatever reason (ie stuck fermentation) and the fresh yeast went nuts. Just some ideas but I'm no expert.

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Adding extra yeast does NOT cause bottle bombs, adding too much sugar does. You can add all the yeast your heart desires and if fermentation is complete then it's ONLY going to eat the sugar you added to it.

IF of course fermentation is complete.

The best analogy is 10 guys in a dorm room eating one pizza as opposed to 1 guy eating 10....When you add more yeast you're only adding more eaters, not more food, the amount of waste (co2) is still going to be the same, you only get x amount of co2 from y amount of sugar, no matter how many folks are eating it, no more or less. Now if the 1 guy manages to eat all 10 pizzas, or if the 10 guys in the dormroom each eat one pizza, then the amount of gas produced in the tight quarters is going to rise incrementally.

This is why it is idiotic to, if your beer hasn't carbed, to add sugar. If you've already added your priming sugar, the problem is not with the foodsource, its with the eaters. So you add more eaters, not more food. If you add more sugar, you run the risk of bottle bombs if the yeast ever decides to wake up and eat ALL the food both old and new that you fed them..

More than likely you're bottle bombs were caused by the rise in temp. Gas expands when it's warm....So the gas expanded in the bottles creating more pressure. And more than likely the two bottles that blew had some small flaws in them, that the expanding gas exploited. I get one or two bottle bombs every summer for that very reason. It's nothing to stress out about, or anything you can really control, if you are going to have temp swings. Obviously if you live in a colder clime, or you don't plan on going anywhere during the summer and turn your air down, then you don't run the risk of it.

Revvy said:

Adding extra yeast does NOT cause bottle bombs, adding too much sugar does. You can add all the yeast your heart desires and if fermentation is complete then it's ONLY going to eat the sugar you added to it.

IF of course fermentation is complete.

The best analogy is 10 guys in a dorm room eating one pizza as opposed to 1 guy eating 10....When you add more yeast you're only adding more eaters, not more food, the amount of waste (co2) is still going to be the same, you only get x amount of co2 from y amount of sugar, no matter how many folks are eating it, no more or less. Now if the 1 guy manages to eat all 10 pizzas, or if the 10 guys in the dormroom each eat one pizza, then the amount of gas produced in the tight quarters is going to rise incrementally.

This is why it is idiotic to, if your beer hasn't carbed, to add sugar. If you've already added your priming sugar, the problem is not with the foodsource, its with the eaters. So you add more eaters, not more food. If you add more sugar, you run the risk of bottle bombs if the yeast ever decides to wake up and eat ALL the food both old and new that you fed them..

More than likely you're bottle bombs were caused by the rise in temp. Gas expands when it's warm....So the gas expanded in the bottles creating more pressure. And more than likely the two bottles that blew had some small flaws in them, that the expanding gas exploited. I get one or two bottle bombs every summer for that very reason. It's nothing to stress out about, or anything you can really control, if you are going to have temp swings. Obviously if you live in a colder clime, or you don't plan on going anywhere during the summer and turn your air down, then you don't run the risk of it.

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As you said, assuming fermentation is complete. We do not know it was in fact complete which is why I said adding extra yeast could have led to a bottle bomb. In a case where the yeast got stuck, died or whatever, could they not ferment out in the bottle causing a bottle bomb? The sugar would still be there from the pre mature end of fermentation in the primary thus adding too much sugar could not be the ONLY way a bottle bomb could happen in a case where fresh yeast is added no?

Not being argumentative here (with someone obviously more experienced than myself). Just trying to learn myself.

Either way the heat explanation makes a lot of since to me as well.

Did you take a FG before bottling?

just my .02 but like in reevy's example which made sense to me if one guy eats 6 out of 8 slices of a large pizza then a dozen more guys come in there's only 2 slices left no matter how you dice it up so there is a limited amt of food no matter how infinite the amount of people or in our case yeast. so even if it wasn't completely fermented out I don't think it would make a bottle bomb. now that poses a good question though if you added more sugar to the mix and it wasn't fully fermented and I guess that would be like adding another pizza a dozzen guys and a small room with no way to escape....... Damnit I'm confused again comon REEEVVVVVYYYYY to the rescue please.

mrduna01 said:

As you said, assuming fermentation is complete.

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AHem...the OP had it sitting for 2 months before he bottled. And took hydro readings before bottle....Highly doubtful he had a stuck fermentation or anything else where adding more yeast could do more harm.

smmcdermott said:

So I recently brewed a NB Scottish Wee Heavy. I went to London for two months for work, so brewed it right before leaving, let it ferment and then put in the basement for the duration of the two months. All readings indicating fermentation was done when i got back.

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Well, if the yeast originally was London Ale yeast or something and it attenuated 62%, and then S05 was added, it could in theory be the cause of the bottle bombs. I mean, I've had S05 go up to 80%.

What I would suggest is not reyeasting unless a lager or another case where there was a long secondary, and using a similar/same yeast if it's necessary.

I was thinking it was the rise in temperature as well. I used Wyeast 1728 Scottish Ale.

I thought because it was in secondary for so long i needed to add yeast. WOOOPS. Live and learn.

I found a 1 L fliptop with the bottom blown out last night. Fortunately it was in a Rubbermaid. I had tried a couple already and they tasted great. I'm assuming the hot spell,(low eighties in the basement), took advantage of a defective fliptop. I have to figure out how to refrigerate the rest, I'm out of space!