For nearly 40 years, beer drinkers in post-World War II America were conditioned to think the best beer was a bright golden color—clean and crisp without a hint of haziness, even at palate-numbing temperatures. A well-made beer was transparent and devoid of any sediment.
There were reasons, both cultural and commercial, that this was the case in post-Prohibition America: Families with German roots controlled most of the rapidly growing domestic breweries in the 1940s and 1950s. The trend accelerated as industry consolidation took hold during the 1960s. Lager beers became omnipresent. In addition, as beer was shipped farther from its point of origin and spent more time in wholesaler warehouses, filtering became important to stabilize the product and extend shelf life.
By the second half of the 20th century, pilsner-style lagers had won the beauty contest, thanks to the style’s thirst-inducing Champagnelike appearance.
Beers are filtered, using either cake or surface methods, and classified into three basic levels: rough, fine and sterile. Using cake or depth filtration, beer passes through a powder substance, such as diatomaceous earth (fossilized marine alga diatoms), finings (isinglass, the swim bladders of fish) or perlite (volcanic glass). Surface filtration uses membranes to filter beer. With lautering, the grain bed acts as a rough filter. In lager beers, gravity helps the process, as the beer is dropped bright while aging. Some brewers also use a technique called cold filtering, where proteins clump together at lower temperatures and are easier to remove. While homebrewers filter beer at 5 microns to remove yeast, grains and hop sediment, commercial brewers typically go much further to as low as 0.5 microns.
As craft brewing expanded, some domestic brewers came to realize that filtration can go too far, stripping away the natural goodness of beer. Overfiltering can take out color, hop bitterness and proteins that add body and help form the beer’s head.
“I appreciate the extra mouthfeel and head retention of unfiltered beer,” says Andy Brown, the brewer at Wynkoop Brewing Co. in Denver, CO. Brown had been taught at brewing school that filtering was an integral part of brewing. Then he had an internship under Dick Cantwell at Elysian Brewing Co. in Washington state, where filtering was rarely used. After spending time at Left Hand Brewing Co., Brown came to Wynkoop, where beers such as the B3K Schwarzbier are unfiltered hits.
