Man, being reasonable, must get drunk; the best of life is but intoxication.
— Lord Byron, Don Juan, Canto II
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After mashing is complete, we must extract wort sugars from the grain bed. This involves two processes: lautering and sparging. These two terms are collectively referred to simply as runoff.
Lautering is the physical separation of liquid from the solids. Sparging involves rinsing the solids that remain with hot water so as to leave behind as little sugar as possible. The combination of lautering the grain and sparging it with additional water results in a kettle full of wort that is ready to be boiled with hops, just as you would if you were using extract.
Lautering
Lautering comes from the German läutern, meaning to clarify, clear, or refine. Lautering takes place after the mash and refers to the process by which wort is separated from the grain bed and collected in the brew kettle. It begins with Vorlauf and ends when the final mash runnings dribble into the kettle.
Vorlauf is the first step in lautering. Another German word, it refers to the initial runnings from the mash-lauter tun, which contain particulates from the mash. Although such particles won’t necessarily damage the final beer, it’s best to minimize the husk material that ends up in the boil kettle. Too much husk could translate to astringency in the finished beer.
Vorlauf runnings are best collected in a measuring cup or pitcher. A capacity of 2 quarts (2 l) should be plenty. Carefully opening the valve to the mash-lauter tun, you collect these initial runnings and observe the clarity of the flow. Once the wort is running relatively clear—which is to say, no chunks of grain—the flow is diverted to the boil kettle to collect the first runnings.
The small amount of wort collected during Vorlauf is then carefully poured back on top of the grain bed (right) so that it has an opportunity to filter through the husks and emerge as clear wort. You do this as gently as possible so as not to disturb the grain.
You may have to repeat this several times for the wort to run clear. Although we use the term “clear,” it’s likely that the wort will be rather cloudy, but it should be free of grain chunks.
With the wort running clearly and the outflow of the lauter tun flowing into the boil kettle, it’s possible to slowly open the valve a little farther to speed up the process. Do this very slowly and don’t tempt fate. If the liquid gets moving too quickly, the grain bed may compact, leading to a stuck mash that is reluctant to give up its precious liquid. With practice, you’ll learn how far you can open the valve on your system: Some are more permissive than others.
After the initial runnings have drained from the mash tun, it’s time to sparge. Close the valve and move on!
Sparging
The word sparge comes from the Latin spargere, meaning “to sprinkle or scatter.” In most commercial breweries, hot water is sprinkled over the grain bed during lautering to rinse the mashed grains of residual malt sugars. Among homebrewers, sparging is used more generically to describe any method of rinsing malt sugars from the mash, whether or not any sprinkling actually occurs. Three methods are popular:
- Batch sparging is a technique practiced, to the best of my knowledge, exclusively by homebrewers. Rather than continuously sprinkling hot water over the grain bed during lautering, one or two batches of hot water are added to the grain and then drained into the kettle. Batch sparging has the potential to be slightly less efficient than fly sparging, but it is fast. And with practice, it can yield results that are just as good as traditional methods.
- Fly sparging, also called continuous or German sparging, is the traditional method by which hot water is sprinkled over the grain bed as it is lautered. This process generally extracts more available sugars than other methods, but it is slow and can take an hour or more at homebrew scales.
- No sparging is relatively uncommon, and we won’t cover it in any depth. But it’s worth being familiar with it. In no-sparge methods, grain is mashed using the entire batch’s volume of water instead of dividing the water between mash and sparge. While this process saves time, it does so at the cost of efficiency, meaning more grain is needed to produce wort of the same strength as batch and fly methods.
Batch Sparge
Many homebrewers batch sparge instead of fly sparge. Batch sparging is a variation on the traditional British practice of parti-gyle brewing, through which (I’m oversimplifying here for brevity’s sake) different beers were produced from each set of runnings. The first runnings might become a barleywine, the second runnings a pale ale, and the third runnings an ordinary bitter. Batch sparging simply combines all of the runnings together into a single wort.
To execute a batch sparge, measure the volume of wort you collected in the first runnings and subtract it from the total batch volume. Let’s say you are brewing 5 gallons (19 l) of beer with an expected pre-boil volume of 6.5 gallons (24.6 l), which means you need 6.5 gallons (24.6 l) total. Here’s the process to follow after the mash.
1. When the mash is complete, open the valve to the mash-lauter tun and collect first runnings until the wort runs clear. Cloudy wort is fine. Chunks of grain are not.
2. When the wort starts to run clear, direct the flow into your boil kettle.
3. Gently pour those initial chunky runnings back on top of the grain bed.
4. When the first runnings have been collected, close the valve and measure the volume you’ve collected. Let’s say you collected 1 gallon (3.8 l) of wort in the first runnings. You need 5.5 gallons (20.8 l) more of hot (170°F/77°C) sparge water.
5. Add half of the total sparge water (2.75 gal/10.4 l) to the mash. Stir thoroughly and wait 5 minutes for the grain to settle.
6. Repeat steps 1 and 2, first collecting a small amount of wort until it runs clear, then run the wort off into the boil kettle to mix with the first runnings. These are your second runnings. As before, gently add the chunky wort back to the top of the grain bed.
7. Repeat once more with the remaining sparge water (2.75 gal/10.4 l) to collect a set of third runnings.
8. You should now have 6.5 gallons (24.6 l) of wort that you can boil with hops!
I recommend that brewers start with batch sparging because it’s easy and requires little additional equipment. Continuous (fly) sparging is a little trickier because hot water is sprinkled over the top of the grain bed at the same time as wort is drained from the bottom. The flow rates of the incoming water and outgoing wort have to match to keep the grain bed from becoming compacted.
When done correctly, fly sparging sets up a continuous flow of ever-weaker wort. Sparging continues until the desired volume of wort is collected, or until the specific gravity of the outflow drops below 1.008–1.010. Over-sparging, which means continuing to sparge after the gravity of the runoff falls below this threshold, can extract undesirable compounds from the husks that lend an astringent flavor to your homebrew.
Moving On
That’s it! Lautering and sparging aren’t mysterious, despite the esoteric names. They’re simply methods to get as much wort as possible out of your mash.
And with an end to lautering and sparging comes the end of the all-grain process. All-grain is just another way to satisfy the third of the essential steps, wort preparation. Once you have a kettle full of fresh wort, you can continue on to the boil, just as you did when brewing from extract.
This is an excerpt from our Illustrated Guide to Homebrewing by Dave Carpenter. Want to read the whole thing? Download it here.