① Introduction
Lauter Tun is a vessel for separating the wort from the solids of the mash. See grant, lautering, mashing, and sparging. A lauter tun works much like a large sieve. It normally has a slotted, perforated floor, also called a false bottom, which holds the spent milled grains, while allowing the wort to filter through the grain bed and collect in the space beneath; the wort then runs to the brew kettle.
Mashing occurs in a separate mash mixer, in which case the mash must be transferred by a pump to the lauter tun. The mash is usually pumped in from the bottom or side of the vessel to avoid excessive aeration of the mash. See hot-side aeration, oxidation, and staling. At the beginning of the run-off, the wort is usually recirculated through the grain bed as a filter mass, until the run-off appears clear through a sight glass in the recirculation plumbing.
