Unlike beers stored in a regular keg, cask-conditioned brew goes in unfiltered and undergoes a secondary fermentation in the container (aka the cask). The yeasts remain alive, affecting the beer’s flavors and character. A good beer on cask is a great beer, but attention newbies: Cask brews are served at a warmer temperature than regular draughts.

Here’s where to try them.

Cask Central
Every spring the Washington Beer Commission (­washingtonbeer.com) organizes a cask festival at which several dozen in-state breweries pour from 
over 70 different casks. It’s well worth the $35 cost 
of admission.

Unfiltered Pub Crawl
There are too many pubs tapping casks to list them all, but here is a sampling: West Seattle pub the Cask
(thecaskseattle.com) plays host to a revolving set of fresh regional brewskies, and the Hopvine (3pubs.com/hopvine.html) staff taps a cask every Monday, an event that coincides nicely with the Capitol Hill pub’s 5 to 7pm happy hour. Elliott Bay’s West Seattle brewpub pops a vintage cask one Wednesday a month, the Burien pub does the same on Thursday (elliottbaybrewing.com).

The Redmond Two-Step
Equipped with a few tables and a tiny bar, Redmond beer and wine store Malt and Vine (maltandvine.com) doubles as a sipping spot for serious geeks, who wander in on Wednesdays to try the cask of the week. Nearby, visit stellar brewery Black Raven (blackravenbrewing.com); the staff taps a firkin, an 11-gallon cask, every Wednesday at 4pm.

Thirsty Thursday
On Thursday, May 19, the first day of Seattle Beer Week 2011 (seattlebeerweek.com), West Seattle’s Beveridge Place Pub (beveridgeplacepub.com) hosts its annual Cask-o-Rama, a rowdy celebration of local beer and your chance to try cask brews exclusively produced in Seattle.