is a device for removing suspended particulate from beer. The filter construction consists of 4–5 mm (0.16–0.2 in) sheets pressed between plates with inlet and outlet channels. Modern filter sheets come in various nominally rated porosities, ranging from coarse to fine to sterile. The sheets themselves may be made from any number of materials, but they have traditionally been made from cellulose impregnated with diatomaceous earth. The sheets may be quickly blinded, depending on the turbidity of the beer to be filtered. Although it is easy to use otherwise, sheet filtration of turbid beer can be slow and cumbersome, requiring frequent back-flushing. This is why sheet filters tend to be more popular nowadays with small-batch breweries than with larger ones. Larger breweries tend to prefer membrane candle filters instead. See candle filter. Considering that beer making has been around for at least 8,000 years and probably longer, beer filtration has a surprisingly brief history. The first beer filter was registered with the German Imperial Patent Office only on June 4, 1878, by Lorenz Adelbert Enzinger, a Bavarian from Wasserburg who had moved to Worms in the Rhineland. Enzinger’s device consisted of several iron plates with paper leaves as a filter medium. These paper sheets had to be replaced after each filtration. That same year, Enzinger formed a company to manufacture and market his filter, and within just 8 years, he had sold his 1,000th filter. The first filter sheet capable of sterile filtration, that is, of trapping even tiny microbes, was developed in 1913 by the German chemist Friedrich Schmitthenner, who worked for the Seitz works, a company founded in 1887 in Bad Kreuznach. The Enzinger and Seitz works merged in 1982 and, after several additional mergers and acquisitions, have evolved into the modern German beverage bottling and packaging technology company KHS.

See also filtration.