Lautering is the process of separating sweet wort from mashed grain. Most homebrewers mash and lauter in the same vessel, a combination mash-and-lauter tun (MLT), while large commercial breweries usually pump the mash to a dedicated lauter tun, thus making the mash tun available to start a new brew.
Lautering (separating wort from the grain bed) and sparging (liberating wort sugars from the grain bed) are so intimately linked that we sometimes don’t think of them as distinct processes. But not every sparge method is ideally suited to every lautering device, and knowing what works best for your system (or conversely, knowing what system works best for your preferred sparge method) can help you get the most out of your grain.
Homebrewers usually sparge in one of two ways:
- Fly sparging (also called continuous or German sparging) involves slowly running off wort from the bottom of the grain bed while simultaneously adding hot water (often sprinkled with a sparge arm) to the top at the same rate. As gravity pulls hot water through the grain, the water picks up sugar, resulting in continuous rinsing of sugar from top to bottom.
- Batch sparging (sometimes called British sparging) involves adding hot water to the grain bed in one or two large batches, mixing it thoroughly with the grist, and draining it from the tun. Because all of the hot sparge water is added at once in each batch, the wort sugars are extracted fairly uniformly from throughout the grain bed.
Homebrewers employ both methods, but some lautering options are better than others, depending on the method you prefer.