Lautering and Sparging Questions Answered

Many beginning homebrewers don’t understand the term lautering.  In fact, there are many homebrewers who are confused about the difference between lautering vs sparging, mash tun vs lauter tun, and mashing vs lautering.  I’ll try and simplify these questions now.

First off, you have The Mash.  Mashing is the chemical and enzymatic process in which milled grain and liquor (your treated brewing water) are combined in a vessel (the mash tun) and allowed to set for a specified period of time (the saccharification rest) at a specified temperature to facilitate the conversion of the malted grain and unmalted adjuncts into sugar. 

Okay, the specified temperature determines its fermentability and body/mouthfeel and turns the malt and adjuncts into sweet wort.  The specified time is normally between 45 and 90 minutes (most often 60 minutes).  If you want to minimize the length of your brew day, run a starch conversion test at 45 minutes to check for full starch conversion.  If starch conversion is complete, the mash is over.

So now we have the sweet wort in the mash tun and starch conversion is complete.  It is time to separate the clear sweet wort from all the solids (grain and adjuncts).  This is basically the definition of lautering. 

In commercial breweries, the mash tun is a separate vessel in which the mash is conducted.  The mash is pumped over into a lauter tun for separation so that another batch of beer can be started in the mash tun.  

Lautering-Images of a Mash-Lauter Tun MLT

10 Gallon Cooler Mash-Lauter Tun MLT and Hot Liquor Tank HLT
Inside 10 Gallon Mash-Lauter Tun Showing False Bottom
MLT and HLT with Sparge Setup

For almost all homebrewers, the mash tun and lauter tun are combined (see the pics above).  What makes a vessel a lauter tun is the false bottom (or braid, slotted tubes, etc. which facilitate filtering the liquid from the wort).  No heat is added to the lauter tun since conversion is complete.  Thus, lautering is a physical process where mashing is a chemical and enzymatic (biological) process.

The Process of Lautering

As a process, laugering is sometimes broken down into three steps:

1.       Mashout-is where the temperature of the mash is increased to approximately 170° F (77° C) to accomplish two things: First this temperature stops the action of the enzymes that were activated in the mash, and thus stops the conversion of starch to sugar.  And second, heating the mash thins it out so that it will flow and drain better.  This is accomplished by adding heat to the mash tun or simply by adding hot water to the mash tun.  This step is not always needed but is important when you are using more than 25% wheat or oats or if the ratio of water to grist is less than 1-1/2 quarts/lb. 

2.       Recirculation occurs when the wort is removed from the bottom of the mash tun and returned at the top to facilitate clarification.  In a RIMS or HERMS or in most commercial breweries, this process is monitored until the wort is clear (measured by a sight glass or turbidity meter).  

For those who do their all grain brewing in coolers, this step is abbreviated by performing a Vorlauf.  A Vorlauf is simply a process of setting the grain bed and clarifying the wort.  After the mash is complete and before you begin to drain the wort into the kettle, you simply pull a small quantity (1-2 qts or liters) of wort from the bottom of the mash tun and return it gently to the top.  Continue this process until there are no chunks of grain remaining and the wort is somewhat clear.   It should be noted that the wort will not get nearly as clear from a vorlauf as it will from a full recirculation of the mash, but it is sufficient for most homebrewers.

3.       Sparging means to rinse the grain bed to remove as much sugar as possible.  The volume of hot water is normally calculated by the brewing software and presented on the brew sheet.  

When using coolers, I’ll normally raise the temperature of the sparge water a few degrees above the set temperature (normally about 167° – 185° F / 75° – 85° C) to allow for cooling during the saccharification rest.  The sparge water is kept in the Hot Liquor Tank (HLT) and the sparge is normally conducted in the lauter tun (or mash-lauter tun MLT).  

There are two ways to sparge.  One, mentioned above is the fly-sparge and the other is the batch-sparge

During the batch sparge (derived from the typical British brewing practices of parti-gyle brewing where two or more beers are made from a single mash but boiled separately) the entire volume of wort is drained before sparging and then a volume of hot water is added to the drained mash and stirred.  After about 10 minutes the wort is drained again.  This method is a little less efficient but does not extract any tannins or raise the pH of the mash like a long fly sparge can.


So, in conclusion, here are the simplified answers to the questions raised in the first paragraph:

1.       What is the difference between lautering and sparging?  Sparging is the rinsing portion of the process of lautering.  Lautering is simply the process of using the grain bed as a filter medium to drain and rinse the sweet wort through as it moves to the next step of the brewing process, the boil.

2.       What is the difference between a mash tun vs a lauter tun?  In homebrewing there is normally no difference, ie. they are the same vessel.  In commercial brewing, where multiple batches are brewed in every day, the mash tun is a separate vessel because it is needed for the next batch of beer and is used continuously while the sweet wort is moved to a separate lauter tun for the long process of recirculation to clarify and sparging to rinse the wort before the boil.

3.       And finally, what is the difference between mashing and lautering?  Mashing is the chemical and biological (enzymatic) process in which the crushed grain and liquor (your treated brewing water) are combined in a vessel (the mash tun) and allowed to set for a specified period of time (the saccharification rest) at a specified temperature to facilitate converting the starch in the grain to sugar.  

Whereas, lautering is simply the physical process of taking the sweet wort, the results of the mashing process, and draining and rinsing it through the grain bed to clarify it and remove as much of the valuable sugars as possible before the boil.

References: Information for this article on lautering was adapted from the Wilipedia page on Lautering,  the article in Craft Beer & Brewing Magazine:  Lautering and Sparging  by Dave Carpenter published  02-09-2016, Chapter 17 of How to Brew by John Palmer entitled “Aspects of Lautering”.

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