Essay17 October 2026 · US trade · Industry

Why Firestone Walker chose Fuller’s yeast

Firestone Walker’s Double Barrel Ale took silver in English-Style Pale Ale at the Great American Beer Festival this month. The yeast it was built on came from a laboratory in Oregon, catalogued as a Fuller’s ESB strain.

The American influence on British beer is usually told through hops. This one runs the other way: a Californian brewery choosing an English yeast despite a cleaner alternative, and keeping something of its character ever since.

Why they chose it

David Walker, the English half of Firestone Walker, set out how the brewery picked the strain for Double Barrel Ale in a letter to Jeffrey House this October, forwarded to us with his permission to quote. The same passages appear in Gordon A. Ponce’s account of the transatlantic loop at The Craft Beer Finder. What decided it was beer trials.

“The number given to the original DBA yeast (Wyeast) we can’t recall at the moment, but it was a Fullers ESB yeast. Why did we use it? Because in beer trials, that’s the one we liked best even though the Chico yeast was cleaner.”

That last clause is the whole thing. Chico, the Sierra Nevada strain and the workhorse of American craft, was the cleaner ferment, and they knew it. Cleaner is a flavour word here, not a hygiene one: a ferment that leaves less of itself behind in the beer. They chose the Fuller’s ESB yeast anyway. They preferred the beer it made. Wyeast is a yeast laboratory in Oregon. The original catalogue number has not yet been confirmed.

The yeast was not the only English thing they chose. DBA has been partially fermented since 1996 in what the brewery calls the Firestone Union, a set of individual 60-gallon oak barrels that Firestone Walker says was inspired by the 150-year-old Burton Union process and describes as “a nod to the traditional cask-fermented English ales that first inspired us”. So an English yeast went into an English fermentation method, and neither was the easier option. The brewery’s own account of the barrels has commercial brewers abandoning the process for the additional care and expense it required.

Adapting the yeast to the brewery

A yeast that settles readily is easier to collect for the next brew. But if it settles before finishing its clean-up work, that advantage becomes a problem.

“The Fullers yeast was a prodigious producer and flocculator, which was beneficial when reharvesting yeast for future brews. But that same flocculation characteristic lead to Diacetyl issues.”

Diacetyl is the buttery, butterscotch note that most brewers spend their time getting rid of, and the way they get rid of it is to leave the yeast in the beer long enough to take it back up. A strain that flocculates hard can be at the bottom of the tank before that is done. The clean-up crew clocks off early.

Walker describes what that meant in a young brewery’s laboratory:

“In the early days our lab, such as it was, could measure diacetyl in the tank and its reduction during maturation, but we couldn’t measure its precursor. Our issues with diacetyl occurred during packaging when the hidden precursor mixed with a little oxygen and turned into diacetyl.”

That is the trap, and it is a precise one. They could watch the fault fall away in the tank and sign the beer off. What they could not see was the compound waiting behind it, which, in Walker’s account, became diacetyl when exposed to oxygen during packaging.

“It was a great yeast when we could tame it, but a nightmare otherwise and we adjusted within a few years.”

Fuller’s in America

Fuller’s already had an American audience, and Jeffrey House had helped build it. House founded Thames America Trading Company at the turn of 1980 and brought London Pride and ESB to the United States, with draught ESB following in 1987. We have written before about the other direction of that trade: Anchor’s beers crossing back in Fuller’s returnable kegs for a London pub trial in late 1991.

Walker’s own introduction came earlier, and was more personal than the imports: House says Walker first drank London Pride in London at eighteen, and visited the brewery at Chiswick later.

The continuing Fuller’s influence

Within a few years, Firestone Walker moved to a more reliable derivative of the original yeast. Read what Walker says it kept:

“We eventually morphed to a derivation of this and more reliable for our needs; now our OG House Ale yeast. Still essentially a Fullers/London yeast.”