How to Avoid Bottle Bombs
Many people new to home brewing underestimate the power of carbonation in glass bottles. A small amount of leftover sugar can make a refreshing bubbly brew. A large amount can lead to glass shrapnel and wasted mead.
To avoid this issue, you need to know what causes it and how to prevent it. Bottle bombs are caused by actively fermenting yeast converting sugar into Carbon Dioxide (CO2). This CO2 production increases pressure inside the bottle. If the pressure exceeds what the bottle can handle, it explodes!
Best case scenario, you make a mess with spilt mead and broken glass. Worst-case scenario, you or your pet needs surgery.
Several ways are possible to prevent yeast from causing bottle bombs. Some are situation-specific. Some are just a terrible idea.
Stabilisation
By far the safest way to prevent bottle bombs is to stabilise the mead with potassium metabisulfite and potassium sorbate. These stabilisers prevent yeast metabolism and proliferation. As a result, no sugar is metabolised into CO2. See our How to Stabilise Mead article for more details.
So when should you stabilise?
1. For large batches you plan to age for years. Stabilising also adds some protection from oxidation making it very useful for long-term aging.
2. For non-carbonation friendly bottles.
3. For low ABV batches you wish to backsweeten.
Deplete All Sugar (Dry Mead)
“Dry” here means no residual sugar in the mead. If your fermentation continues until the gravity is below 0.980, you are safe to bottle. If there is no sugar, no CO2 can be produced. As you can tell, this would only work for bone dry meads. Anything else needs an alternative method.
Push the Yeast to Max ABV
I am notorious for this method. It is not without risk, but it can be done with proper precautions. I am the first to admit stabilising is safer.
If you are still reading, I can at least teach you the safest way to do it:
1. Push the yeast to the ABV limit (~16% ABV For Wyeast 1388). See the next paragraph for more details. This is not always perfect, so...
2. Use carbonation-friendly bottles or keg the mead. Even if I get a bit of pressure, the bottles/kegs are fine.
3. Refrigerate the bottles. I generally don’t because I have a good handle of this method, but it is safer. Also, batches that you drink cannot make bottle bombs!
4. Store bottles in a sealed Tupperware container. If they explode, at least the mess is contained.
The ABV limit depends on your yeast and SNA practices. For Wyeast 1388, I know it will ferment 120 Points (1.120 to 1.000). I simply add honey to my desired sweetness upfront. For example, if I want a final gravity of 1.020, I start with 1.140.
If you use a different yeast, you will have to work out its ABV tolerance in YOUR hands. Don’t trust published tolerance! Yeast don’t read packet inserts! This way is not perfect, so be sure to bottle in pressure-friendly bottles and store in Tupperware just in case.
Pasteurise
I do not recommend this method. I only list it because it does technically work, but the risk of a boiling hot, pressurized bottle exploding into glass shrapnel and liquid lava is not something I can promote. Please just stabilise.
Products Linked In This Article
Potassium Metabisulfite
available in 10, 50 and 100 gram pouch sizes
Potassium Sorbate
available in 10, 50 and 100 gram pouch sizes
