conditioning
Cask conditioning
Complete fermentation and carbonation inside the cask the beer will be served from, so it arrives at the drinker alive.
What is actually happening
- Racked while still working. Beer goes into the cask before fermentation is quite finished, with live yeast still in it. The sediment settles to the belly of the cask.
- Conditioned in the cellar. The remaining yeast produces a small amount of carbon dioxide, which dissolves and gives cask beer its gentle natural condition. No gas is added.
- Vented, then served. A soft spile in the shive lets excess pressure out. From the moment it is vented, air enters as beer leaves — which is what starts the clock.
The beer is racked with a small quantity of residual fermentable material and live yeast, often with finings and sometimes with priming sugar or dry hops. Secondary fermentation in the cellar generates the beer’s gentle natural carbonation.
Because the cask is vented and beer is replaced by air as it is drawn, a broached cask has a service life of a few days. That is not a flaw in the format; it is the consequence of serving live beer.
Typical conditions
| Temperature | 11–14°C |
|---|---|
| Duration | 3–14 days |
| Scale | Used at both homebrew and commercial scale |
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.
- Oxidation — The universal ageing fault: oxygen degrades beer into papery, cardboard-like staleness, and dulls everything that made it good.
- Undercarbonation — Too little dissolved CO₂, leaving the beer flat and dull — carbonation carries aroma as well as providing texture.
Styles where this step is decisive
- Ordinary bitter
The everyday British cask ale: low in strength, gently bitter, and built to be drunk in pints over a whole evening.
- Best bitter
A step up from ordinary bitter in strength and depth, with more malt body while staying firmly sessionable.
- Dark mild
A low-strength dark British ale, gently sweet and nutty, built for drinking in quantity after physical work.
- English pale ale
The bottled British pale ale tradition: biscuity malt, earthy and floral English hops, and a firm, dry, mineral finish.
- Strong bitter
The strongest of the bitters, with pronounced malt richness, firm bitterness and noticeable fruit from warm fermentation.
- English IPA
The original IPA: a strong, firmly bitter English pale ale with earthy, floral hop character and a dry, mineral finish.
- English porter
The original dark British beer: chocolate and light coffee over a nutty malt base, restrained rather than aggressive.
- English brown ale
A malt-led brown ale with hazelnut and caramel character, moderate strength and a dry, clean finish.
- British golden ale
A modern British cask style: pale, crisp and citrus-hopped, developed to win drinkers back from lager.
- Oatmeal stout
A stout brewed with oats for a silky, full mouthfeel, balancing roast against smoothness rather than sweetness.
- Scottish ale
Malt-forward Scottish ales with caramel depth and very restrained hopping, traditionally graded by shilling price.
- Old ale
A matured English strong ale with dried fruit, treacle and often a trace of oxidative or wild character from age.
- Low-alcohol bitter
A genuinely fermented British ale brewed at very low strength, keeping cask character without dealcoholisation.
Related steps and concepts
- Cellar conditioning — The pub-side half of the process.
- Fining — How the beer is dropped bright in cask.
- Real ale — The campaigning definition built on this practice.
Also at the conditioning stage
Barrel ageing · Blending · Cellar 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.
Cask-conditioned beer completes its fermentation in the container it is served from, retaining live yeast and residual fermentable material, and is dispensed without added carbon dioxide.
Backed by a source
Sources: Campaign for Real Ale; Institute of Brewing & Distilling technical publications