The 13th Fermenter

While presenting cask ale over several occasions last week, I was asked: So, why isn't this firkin made of wood?

First: what's a firkin? A firkin is simply a specific size of English beer cask, one which contains 9 Imperial gallons. That approximately translates to 10.8 US gallons, or 86.4 US pints (16 ounces).


As are kegs, most (but not all) firkins today are constructed of stainless steel.

Prior to the 1930s, although wood may have been the material of the vessel, wood was not necessarily wanted as a flavoring agent. Normal practice would be for brewers and coopers to line their casks with pitch or other substances to prevent the beer from coming into contact with the wood. Wood could be a source of microbiological infection.

Beers today that are deliberately infused with wood flavor might be tasty, but they are not necessarily historically accurate in that practice.

So what is the point of cask ale, the advantage of serving beer from a firkin?

Imagine a firkin cask as a small fermenter. Beer is transferred, still fermenting, from large brewery vats to this smaller 10.8 gallon brewery 'vat'.

Cask-conditioned ale —real ale— is beer in its ideal state, literally fresh from the fermenter, still alive. Rather than a drinker traveling to a brewery, the brewery has figuratively and literally come to the drinker. The very opposite of an aged wine cask, a firkin is indeed the 13th fermenter. Brewery fresh.

And what does 'fresh beer' taste like? What does fresh bread taste like, straight out of the oven?

It's an ineffable quintessence of flavor.

• Go here for a handy comparison of serving sizes and containers.
• Go here for more on one brewery's wooden casks.