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.
False Bottom
The false bottom is standard in commercial breweries and very common in homebrew systems as well. It is the ideal lautering device for those who fly sparge because the uniform hole pattern prevents channeling, which can reduce extraction efficiency.
False bottoms are available from most homebrew supply stores. One well-known false bottom, the Jaybird, is manufactured and distributed exclusively by NorCal Brewing Solutions. First produced in 2008, the Jaybird false bottom came along when homebrewer Jay Webster came across a few spare sheets of perforated stainless steel and offered to fabricate false bottoms for members of HomeBrewTalk.com. Six hours and 80 private messages later, it was clear that the demand for quality false bottoms was significant. Housed in the 9,000 square foot NorCal Brewing Solutions homebrew store in Redding, California, Jay’s team still custom builds every Jaybird false bottom to a tolerance of 1/64-inch using plasma cutters.
False bottoms are de rigeuer for fly sparging and can also be used to batch sparge if care is taken to lauter slowly so as not to compact the grain bed.
Screen or Braid
A lautering screen or braid is best suited to those who exclusively batch sparge because each batch of runoff is, practically speaking, homogeneous with respect to dissolved sugar. Channeling is not an issue with batch sparging, so the lautering device’s only role is to filter wort from the grain. The most common screen is probably the Bazooka screen or a clone thereof (we understand that the Bazooka screen has been discontinued). For the braid, you can either take one out of a toilet or hot water heater supply hose or Bargain Fittings sells them ready to go.
In theory, the runoff from a batch sparge could flow through the screen and out of the tun as quickly as gravity allows, but in practice, running off too quickly can compact the grain bed and result in a stuck mash. Braids and screens are not recommended for fly sparging due to the likelihood of channeling.
Some homebrewers prefer to lauter using a manifold with regularly spaced slots, which offers the flexibility of either batch sparging or fly sparging. These are effective lautering devices as well and a great DIY project for those who wish to build one. A great advantage of false bottoms, screens, and braids, however, is that they’re readily available off-the-shelf for those of us with limited DIY skills.