Bottle Bombs

Q: Recently we started bottling our homebrew in individual bottles (saved from microbrews we drink). We’ve had two or three bottles suddenly combust, as in the bottle explodes! They were not all from the same batch. Do you know what may cause this and what we can do to avoid this from happening in the future?
— Wendy Lin • New York, New York

A: This question has a rather short, but important answer. Most breweries in the United States use “one-way” glass bottles for packaging. These bottles are lighter in weight compared to returnable bottles and are not intended to be used more than one time. Since the bottle filling and capping process can stress glass bottles, especially these lighter weight types, one-way glass is at greater risk of having bottle failure compared to the heavier returnable type of bottle.

While returnable glass at one time was common in the United States, little if any real use of returnable glass is seen today. There are several reasons for this including logistics of dealing with returnable bottles, the expense of cleaning and preparing for re-use, the unsightly scratches that develop over time and the generic form the bottles usually take. Furthermore, in-line scanners must be used to ensure that damaged glass is not re-used. All of these steps add costs to this type of package. Even European brewers are using more one-way glass because of the marketing advantages to using custom bottles with different shapes and embossed images on the glass surface.

My suggestion is to acquire heavy glass bottles that you know are intended for re-use. At one time this was easy, but today is more and more difficult as the use of returnable glass continues to decline. If you buy new specialty bottles, such as flip-top bottles or champagne bottles with beer bottle sized crown tops, you can use these heavier bottles with little fear of bottle grenades, provided that you have your priming procedures under control.