5 Home Brewing Tips to Avoid the Dreaded Bottle Bomb

by Brad Smith on August 27, 2009 · 11 comments


Today we are going to look at how to avoid the dreaded bottle bomb when homebrewing your own beer. I recall my first bottle bomb vividly. It was my third batch of beer — ever. I was not home at the time, but when I arrived back in my apartment, I knew something was wrong. You see, my third batch of beer happened to be a stout.

The bottle exploded in the kitchen and left dark stout covering the walls, counter, floor and cabinets. It was only a 12 oz bottle, but it looked like someone had repainted the kitchen. Glass was also scattered as far as the living room and a small piece had even embedded itself in the drywall. I realized at that point that this homebrewing thing was a lot more dangerous than I had guessed. Someone could have been hurt.

In the years since, I learned quite a bit more about brewing and bottling. I have not had another beer bottle explode since then. I would like to share a few of my tips with you now:

1. Use High Quality Ingredients

The quality of brewing ingredients in the 1980s was nowhere near the quality home brewers have access to today. However, you still need to be careful when purchasing ingredients – particularly those that look like they have been on the shelf for a while. First, always use fresh malts and malt extract. Older liquid and dried malt extract in particular will ferment much more slowly than comparable all-grain wort. Yeast also has a limited shelf life. Liquid yeast is generally of higher quality than dried packets, but it must be stored under refrigeration and must be used in the recommended shelf life. Liquid yeasts are typically dated – so pay attention to the date when you purchase and use the yeast. Old, expired yeast will ferment slowly or possibly incompletely contributing to exploding bottles.

2. Allow the Beer to Ferment Completely

One of the chief causes of exploding homebrew bottles is beer that has not been fully fermented before bottling. Many home brewers are anxious to drink their newest brew and rush it into the bottle too early. The beer then completes its fermentation in the bottle, producing extra CO2 pressure that can cause bottles to fail. Malt extract based beer will ferment more slowly than a comparable all grain beer, so malt extract brewers are at higher risk. Finally, many extract brewers use plastic buckets with covers that seal poorly. As a result, gas may leak out the edge of the bucket rather than through your airlock. A beginner will interpret the lack of airlock activity as an indicator that fermentation is complete, never realizing that the CO2 from active fermentation is leaking from the cover. I usually allow a minimum of two weeks for an average beer to ferment before bottling, and wait a longer period if brewing a high gravity beer.

3. Use Good Bottles, and Inspect Them

A poor quality bottle is a recipe for disaster. Even under normal carbonation, a beer bottle at room temperature can reach 30+ psi. Never use a twist off bottle – they are too thin and your caps will not properly seal. Select the thickest bottles you can find, clean them thoroughly and inspect each of them by holding them up to a light source each time you use them. Immediately toss any cracked, chipped or thin bottles. Consider purchasing high quality reusable bottles from your homebrew store – these are generally better than disposable commercial bottles. If you use them several times, the cost is quite reasonable.

4. Calculate and Weigh the Right Amount of Priming Sugar

Sugar density varies tremendously depending on who made the sugar – one cup of corn sugar from one manufacturer weigh dramatically more than another. Weigh your priming sugar – don’t just measure it by volume. You can calculate the exact weight of priming sugar needed using a spreadsheet, online calculator or BeerSmith.

5. Store your Beer in a Cool Dark Place

Light and heat are natural enemies of finished beer. Light and heat break down critical flavor compounds, promote additional fermentation and increase the CO2 pressure in the bottle. As you heat a bottle of beer, it also dramatically increases the pressure in the bottle itself. Store your beer in a cool dark place to avoid bottle bombs and preserve its natural flavor.

Thanks for joining us on the BeerSmith Home Brewing Blog. If you have additional suggestions for improving your bottling, or ideas for future articles please leave a comment. As always, feel free to subscribe, share this article with a friend or bookmark it on your favorite social website.

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