Packaging: Priming Sugar, Headspace, and the Bottle Bomb

Dissolve the weighed sugar in a little boiled water, cool it, put it in the bottling vessel, and rack the beer gently onto it. The racking mixes it without splashing. Priming each bottle individually is where inconsistent carbonation comes from, and inconsistent means some bottles are flat and some are over-pressure. A measured tablet or drop per bottle is more consistent than a spoon and still less consistent than batch priming. Stir gently once, if at all. Vigorous stirring at this stage is oxygen introduction at the very last moment, which the oxygen rung says is when the beer is most vulnerable — it will be sitting in the bottle for months.

Fill from the bottom of the bottle with the tube all the way down, and let the level rise. Leave about 25 mm of headspace — enough for the cap to seat and for the liquid to expand, and no more than that. Too little headspace risks the cap being pushed off; too much is a reservoir of air that will oxidise the beer over the months it is stored. Consistent fill height is also what makes the carbonation consistent between bottles. Cap immediately after filling. A row of open filled bottles waiting to be capped is a row of bottles taking on oxygen and whatever is in the air, which is the sanitation rung arriving at the very last step.

Leave the bottles at fermentation temperature for two weeks. The yeast needs warmth to work through the priming sugar, and bottles put straight into a cold store stay flat until they are warmed again. Then open one. That is a real measurement: if it is under-carbonated, the rest need longer; if it gushes, move the whole batch somewhere cool and drink it quickly. Testing one bottle at two weeks is how a problem is found while it can still be managed. After conditioning, cold storage slows everything and keeps it stable. And record what went into the batch — the priming weight, the volume, the temperature, the date — because a carbonation that came out exactly right is worth being able to repeat.