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Over Priming Home Brew Bottle Bomb

Monday, June 1st, 2009

If you happen to over prime your bottled home brew beer, this is what you will get:

home brew bottle bomb

“Huston We Have A Problem”

This beer was very excited to see me!  It had a texture more like soda at least until it settled down.

Over priming creates a veritable fountain of fizz, and if left unattended can shoot off on its own.

A tell tale sign of over priming when the cap begins to buckle. The bubble in the middle should be a dimple.  If you see a cap in this state, make sure to open it over the sink! Some folks call this a bottle bomb, but I have never had one explode. More than likely the cap will shoot off and you will have a sticky mess wherever the beer was stored. One way to contain the situation is to use a bottle opener to gently relieve the pressure without prying off the cap.

beer over priming

The solution to this problem is to add the correct amount of sugar at bottling time. Make sure to measure out how much dextrose (corn sugar) you are using. I use about 3oz by weight for a five gallon batch. Don’t get aggressive with this ingredient, less is more. You can also prime with dry malt extract (DME), however it is more expensive, requires more, and I have not been able to tell the difference.

The hard core home brewers will tell you to solve this problem, keg the beer instead of bottle it. I consider myself a hardcore brewer, and I do keg a lot of my beer. That said, I still enjoy bottling as the flexibility and portability are big advantages, though it does take more time. The photos above were from an experimental one gallon batch of mint porter, which didn’t turn out that great. I manually primed each bottle and a few bottles got too much dextrose.

  1. 3 Responses to “Over Priming Home Brew Bottle Bomb”

  2. To be fair, there are a few possible outcomes to over-sugaring your beer, mostly dependant on your containers.

    Over-foaming is the most common problem, as the photo nicely documents.

    Over-sugaring plus increased storage temperatures can lead to some more drastic results. Copper-top bottles will have the cap forced off enough to allow the beer to foam out. Messy, but not the end of the world. Rocker-top bottles will actually build up pressure until the rocker top is unseated; if the seal wasn’t great to begin with, the beer may have dried into a sugar-stuck seal, in which case the bottom of the bottle will actually break off from the walls of the bottle. (yes, I’ve seen it happen; it’s messy, but safer than the whole metal frame popping off)

    The really scary stuff is if you try to bottle your homebrew in growlers. If you use the cheapest tin screw-tops, you’ll see deformation and bursting just like you would with a copper-top bottle, but if you spend the extra $0.15 for a quality, airtight, plastic threaded cap, then the combination of higher room temperatures and too much sugar can cause a growler to literally detonate. This happened with a batch we made and gave to a friend for St. Paddy’s; he didn’t want to pay much for bottles so he bought growlers, and saved one until mid-July. And stored it in his ground-floor, non-air-conditioned living room. Fortunately, the room was empty when the growler exploded, but he did have to pry shards of glass from the drywall, and that room never did smell like anything other than Irish Stout.

    By That Beer Guy on Jun 12, 2009

  3. Hi, i’m a newbie homebrewer, and I want to start with this Priming system, and my doubt is, I’ve been reading about the volumes of CO2 and the residual CO2 from the first fermentation process, and how to use the “higher” temperature of the fermentation to calculate this residual CO2, but all the pages and some forums say that you have to put the amount of sugar or dextrose for the volumes of CO2 at the same temperature that you fermented, So my question is this what happen with the volumes of CO2 when you put this bottles after been aconditioned at lowers temperature, it will increase? like the Henry’s law explain or it will remain the same at room temperature or refrigerated (2.5 volumes of CO2)?


    By Sebastian on Jan 22, 2024

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