conditioning
Cellar conditioning
Receive, stillage, vent, fine and temperature-manage cask beer in the pub so it reaches the drinker in condition.
Also called cellarmanship.
What is actually happening
The cask is stillaged and left undisturbed for a day or more so the yeast drops. It is then vented with a soft spile to release excess condition, judged by hiss and by taste, and sealed with a hard spile once right.
Cask beer is the only mainstream product where the retailer completes the manufacture. A well-run cellar makes an ordinary beer taste better than it deserves; a poorly-run one serves excellent beer cloudy, flat or sour.
Typical conditions
| Temperature | 11–13°C |
|---|---|
| Scale | A commercial-scale operation |
Ranges, not targets. These describe what is usual across the styles and breweries that use this step, and a value outside the range is a decision rather than an error.
What goes wrong here
Risks rather than certainties. This step does not cause these faults; getting it wrong can.
- Acetic acid — Vinegar character produced by acetic acid bacteria, which need oxygen — so it always points to air ingress.
- Permanent haze — Cloudiness that does not clear with warming, usually from incomplete starch conversion or irreversible protein complexes.
- Dirty dispense lines — Beer spoiled between keg and glass by microbial growth in the lines — a venue problem rather than a brewery one.
Related steps and concepts
- Cask conditioning — The brewery-side half.
- Venting — The key intervention.
- Stillage — Where it happens.
Also at the conditioning stage
Barrel ageing · Blending · Cask conditioning · Conditioning · Dry hopping · Freeze concentration · Lagering
See the whole process in order on how beer is made.
Last reviewed 2026-08-16.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Because air replaces beer drawn from a vented cask, a broached cask has a service life measured in days rather than weeks, after which acetic souring and oxidation become perceptible.
Backed by a source
Sources: Campaign for Real Ale; Institute of Brewing & Distilling technical publications