Lautering and the lauter tun

Lautering normally has three steps: mash-out, recirculation and sparging.

• Mash-out: raise the mash to about 76 C. This stops enzyme action and thins the wort so it runs more easily.
• Recirculation (vorlauf): run the first cloudy wort back over the top of the grain until it runs clear. The grain bed itself is the filter.
• Sparging: rinse the grain with hot water at about 76 C, slowly, so the last of the sugar washes through. Do not go hotter, or tannins come out of the husks.

A lauter tun is a vessel that holds the mash during lautering. It has a false bottom, a plate with many small holes that lets the wort run through and holds back the husks. Large lauter tuns also have rotating rake arms that cut through the bed so it does not pack down. At home, a cool box with a stainless braid or a false bottom does the same job.

Some breweries use a mash filter instead: a stack of cloth plates that squeezes the wort out of a finely milled mash. It works faster and extracts more, but it is industrial equipment. Home brewers use a lauter tun, or the bag method known as brew-in-a-bag, where the grain sits in a mesh bag that is lifted out and drained.

Run off at a trickle, about a litre every two or three minutes in a small system. Rushing packs the bed down and causes a stuck sparge.