The first in a new series for Ferret the Beer. It’s continuing mission to explore strange new beer terms, to seek out new concepts and new stylizations, to boldly go where no beer person has gone before.

[I’ve been watching a lot of Star Trek lately…]

[Etching of the Bass Union system. Via]

The Burton Union system is a system of wooden fermentation vessels used predominantly by the brewers in and around Burton-on-Trent, England in the mid to late 1800s.  This network usually consists of 24-60 large wooden barrel casks (about 150 gallons/ea) laid on their side in rows, suspended off the floor. These barrels are linked together so that wort/beer can be evenly dispersed throughout the Union. At the top of the barrels is a swan neck pipe that connects to a trough suspended over the barrels. This trough, being slightly pitched to one end, is connected to another feeder trough so that the wort/beer can be re-circulated into the barrels.

Actively fermenting wort (usually 12-24 hours after adding the yeast) is fed into the Union, via gravity, from the primary fermentation vessels. As the yeast continues consuming the sugars, it is forced out of the top of the barrels through the swan necks in foamy bursts. The beer runs down the trough, into the feeder vessel and back into the casks to continue its fermentation, all the while leaving behind a large amount of its healthy, viable yeast. This yeast is collected and the beer subsequently becomes steadily brighter and brighter. After about 6 days in the Union, the beer is drained from the barrels and moved to a finishing vessel whereby it’s blended with other beer or packaged.

The most notable users of the Burton Union System were the Bass Brewery and Marston’s Brewery. Unfortunately, it is a labor and capital-intensive process, requiring constant maintenance and, thus, all but one British brewery has abandoned this approach. Marston’s still uses their Union largely for the production of their flagship beer, Pedigree Bitter.


[Modernized Burton Union system seen in Burton-on-Trent at the National Brewery Centre, formerly the Bass Brewery museum and Coors Visitor Centre. Bass has been owned by Molson Coors since 2002. Image via]

Firestone Walker in Paso Robles, CA, operates a modified Burton Union System, calling it Firestone Union. Besides Marston’s, they are recognized as being the only other brewery using a Union Set today. Where Marston’s chooses to use barrels that are more neutral in character, Firestone uses heavy or medium toast American oak barrels to impart a wood flavor to the beer. According to the brewery, this process “improves the fullness of the palate, enhances hop maturity and lends a clean briskness to the finish. The influence of the toasted oak also imparts unique hints of smokiness and vanilla, as well as a subtle fruitiness to the flavor profile.” The beer that most benefits from this effect is their flagship, DBA (Double Barrel Ale). They choose not to collect the yeast or foam that comes out of the fermenting vessels for re-use.

Additional links:

  1. Michael Jackson’s 1992 article on Marston Brewery’s Burton Union System that was going through an expansion at the time
  2. Firestone Walker’s webpage on their Firestone Union System
  3. A video from 2009 where then-head brewer (now-brew master), Matthew Brynildson, discusses the Union process (specifically starts at about 2:20) (via


  1. The Oxford Companion to Beer, edited by Garret Oliver, 2011. “Burton Union system” article by Matthew Brynildson

Do you have any ideas or requests for the BREW LEXICON series? Let me know in the Comments!