Coolship Fetish Engulfs Oregon


The race to develop beers with rare and interesting character is spreading as brewers grapple with increased competition and the need to differentiate themselves. One result of that reality is a growing number of Oregon breweries have installed coolships or plan to.

“I think it’s exciting for brewers because it brings ‘local’ into the brewery on a whole new level,” said Jeff Alworth, author of “The Beer Bible” and a local blogger. “There’s something incredibly seductive about the local-ness of spontaneous fermentation.”

Microflora can vary widely from place to place, even in a small area. Alworth related a story in which buckets of wort were left out overnight in Forest Park, all within reasonably close proximity. The buckets were then pitched into larger batches and left to ferment.

“The amazing thing is they all tasted different,” Alworth said. “Even a couple hundred feet is enough to get a different mix of microbes. It’s crazy. I think yeast is on the frontier of experimentation, and spontaneous fermentation is basically yeast foraging. It has a lot of appeal.”


Part of that appeal may be the risky nature of the approach. Spontaneous fermentation can be done almost anywhere, but the results can be wildly unpredictable. Some places have characters floating around that aren’t conducive to producing good beer. Success is a roll of the dice. That reality means most of those using coolships have done meticulous research prior to launching.

There are, however, exceptions to the meticulous research model. McMenamins Edgefield and Block 15 both viewed their coolship program as largely an experimental venture. At Block 15, the coolship is permanently situated inside and has no direct exposure to outside air.


“We put it in our ‘wild cellar’ with the thought that the resident flora would be enough,” said Nick Arzner, head brewer. “I didn’t have high hopes for the early batches and was pleasantly surprised when they matured into great spontaneous offerings.”

The optimum time for allowing inoculation in an outside setting appears to be during cooler nights in the fall, winter and early spring, depending on location.

“There are also differences in the fermentations inoculated in the fall versus winter or early spring when the trees are starting to bloom in the surrounding orchards,” said Logsdon’s Shilpi Halemane. “These can result in more/less acidic beer, or beer with more/less wild yeast character. Blending from different points in the season can bring those elements together.”

While most coolships are shallow-draft rectangular vessels made from metal, there are plenty of odd presentations. Allegory uses a converted dairy tank. At Edgefield you’ll find an old mash tun. Ale Apothecary, the biggest outlier, uses a carved-out spruce tree.

Some may think the interest in coolship beers is a fad or trend that will go away. But brewers see them as a chance to experiment and expand their skills. In some cases, the vessels will be multipurpose.


“We’ll use it for spontaneous inoculation beers, as well as other projects,” said Sean Burke, head brewer at Von Ebert. “We’ll put fresh hops in there as well other ingredients that seem like they might be fun to play with: tree branches, blueberry bushes, who knows? Experimentation is the name of the game.”

At pFriem, Lord has several things in mind.

“First, we can taste the difference between ‘wild or spontaneous’ beers and those inoculated with a lab culture,” he said. “We’ll continue to rely on lab cultures for many of our specialty beers. The coolship will allow us to add another beautiful and complex color to our palette. Second, while we already seek to express time and place using fresh, local fruits, the utilization of native microflora represents the ultimate next step in the expression of our unique terroir.” •

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March 1, 2019

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