There’s not that many reasons for your precious beer to explode, in fact, generally only one reason. The short answer is that it was bottled to soon…This is a common occurrence in spring and early summer. Now the long explanation. As you know the way to get bubbles in your beer is to trap them inside the bottle. I’m trying to figure out where to start with this explanation and I guess it all starts with understanding the relationship between sugar, yeast and temperature.
If you beer is bottled in cooler weather before it is fully finished it will be fine until the weather turns warm and the yeast that has been sleeping in the cool weather becomes more active in the bottles. It’s this activity that creates the gasses that we want to trap in the bottles. If your wort was finished fermenting properly before you bottled it, then the measured amount of sugar you put in will be perfect to create just the right amount of bubbles in your bottle…. However, if it wasn’t finished and you add your sugar to the bottle as instructed, this sugar combined with the unfermented sugar will be to much and will create an excessive amount of pressure in your bottles. This can be a very dangerous situation and must be treated with the utmost caution. See more under the heading of ‘can you explain more to me about yeast’
In desperate situations you can uncap your bottles, therefore releasing some pressure and then recap them. This must be done with the utmost care wearing eye and hand protection.
One other thing that can cause your bottles to explode is if you add more than the recomended amount of sugar to your bottle at the bottling stage of the process. Getting the perfect end result is a matter of getting every step along the way right.
Occasionally a contamination can cause you bottles to explode but this is an extremely rare occurrence.
Its a good habit to always taste your beer before you bottle it as this will indicate what you can expect your brew to taste like in 4-6 weeks time, only better. Don’t think about the fact that it is warm and has no bubbles, just concentrate on the taste.
For more information see ‘Why is temperature so important?’