Lautering

Lautering (/ˈlaʊtərɪŋ/)[1] is the beer brewing process that separates the mash into clear liquid wort and residual grain.

This is a delicate step, as the wrong temperature or pH will extract tannins from the chaff (grain husks) as well, resulting in a bitter brew.

Some homebrewers use English sparging, except that the second batch of water is only held long enough for the grain bed to settle, after which recirculation and draining occurs.

While the basic principle of its operation has remained the same since its first use, technological advances have led to better designed lauter tuns capable of quicker and more complete extraction of the sugars from the grain.

[5] The false bottom in a lauter tun has thin (0.7 to 1.1 mm or 0.028 to 0.043 in) slits to hold back the solids and allow liquids to pass through.

Brewhouses in plain public view, particularly those in brewpubs, often maintain the swan-neck valves and grant for their visual effect.

A good quality lauter tun has rotating rake arms with a central drive unit.

Craft breweries often have manways on the side of the mash tun for spent grain removal, which then must be helped along to a large extent by the brewer.

Some small breweries use a combination mash/lauter tun, in which the rake system cannot be implemented because the mixing mechanism for mashing is of higher importance.