This year's edition of my favorite local brewfest is Saturday, Oct. 29. At Washington Cask Beer Festival VI, around 30 Washington breweries, in addition to some from neighboring states, will be pouring naturally conditioned beers for a happy crowd of beer aficionados. For those less expert, cask-conditioned beer is still a bit of a mystery, but if you've visited Britain and stopped at a good pub or three (preferably listed by the Campaign for Real Ale) you know what to expect. The campaign (CAMRA) is Britain's voluntary organization that promotes beer made the old-fashioned way. Most commercial beers undergo a process that arrests fermentation, after which they are pressurized with CO2 in bottle or keg and shipped to the retailer. Cask-conditioned beer is a living product. Cask beers are in the final stage of fermentation when they are packaged, and CO2 is a natural by-product. They are poured from the container, using gravity, or pumped by hand with a beer engine. Cask beer can be a revelation—rich, aromatic, and subtly textured, bursting with fresh, ripe flavors. Cask beer can also be delicate. Things can go wrong, resulting in infected beer with nasty spoiled flavors. The beers served at the Washington Cask Beer Festival over the years have been good—the few spoiled beers have been yanked right away. Washington brewers are also imaginative. A British cask beer festival might concentrate on indigenous styles, but our cask festival has featured cask-conditioned variations on Belgian styles as well. Local brewers tend to be rather aggressive with styles and flavor profiles, too, so if you're looking for a high-strength IPA with hop bite, you'll probably be in the right place. Herbert's Cask Festival Beer (which is specially brewed collectively by the Washington Brewers Guild members) will be available, as will pub food from Fred's Rivertown Alehouse. Raise your glass and help raise money for the guild, whose goal is to promote quality and value in locally handcrafted beer. There are places in Seattle that go to the trouble to pour naturally conditioned beers. A few that regularly feature them include Maritime Pacific's Jolly Roger Taproom, the Elliott Bay Brewpub in West Seattle, and the Stumbling Monk on Capitol Hill—and that's just for starters. Get out there and explore, and, as they say in Merrie Olde, "ask if it's cask." Washington Cask Beer Festival VI: $35/person in advance, $40/person at door. Noon– 4 p.m. and 6–10 p.m. Sat., Oct. 29. Fisher Pavilion, Seattle Center, 305 Harrison St., www.washingtonbeer.com.