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Dialing in Your Process:  Mashing and Sparging

Dialing in Your Process: Mashing and Sparging

There are literally thousands of ways to homebrew a beer.  Between different equipment combinations, available products and budgets, you can do it just about any way you can dream up as long as you follow the basic science of the process. This week, I wanted to focus on dialing in the mashing and sparging process, talk about some of the science involved, and go over some techniques that might help you boost your efficiency, or even refine your process to make the best beer possible.

Carbon Atom Part of C6H12O6

Dough In With Science

The basic science of the mashing process is pretty simple:  you take malted grain and soak it at a temperature that will allow the enzymes in the grain to take carbohydrates and convert them into sugar that the yeast can eat.  Following this basic step, anyone can make good beer with reasonable consistency, even if their beer differs from batch to batch. Let’s take this basic process and expand a bit.

The enzymes that we’re targeting during a saccharification rest (147° F to 158° F) are Beta and Alpha Amylase.  These enzymes attack the starch present in grains in slightly different ways.  Beta Amylase is actually active from 140° F to 160° F, but the starch in barley doesn’t gelatinize (become water soluble) until 140° F, so we, as brewers, generalize the temperature range a little bit higher to ensure proper gelatinization of the starch so that the enzyme can actually get to it.  Beta Amylase makes the most fermentable sugar by converting a starch called Amylose into maltose sugar. Amylose is a single chain of glucose molecules linked together by their 1st and 4th carbon atoms, known as a 1-4 link. Beta Amylase is able to break this bond, resulting in our favorite two chain sugar, maltose. The only problem is that Beta Amylase can only break the single chain starches of Amylose, which do not branch.

Alpha Amylase also splits 1-4 linkages, but can also break some of the branches found in the other main starch in grain, Amylopectin.  By doing this, it creates single chain starches that the Beta Amylase can then convert. Amylopectin, however, also has 1-6 linkages at it’s branches, so although it allows further access for the Beta Amylase to break single chain starches, it leaves behind branched starches that are unfermentable. This is another reason why we mash inside of a temperature range where both enzymes are active, so that they can work together to create more fermentable wort.  The higher the mash temperature, however, the more of these branched starch structures are left behind, leaving body and residual sugar in your finished beer.

Different lengths and compositions of rope to show amylopectin and amylose

My personal visualization of this process is different lengths of string.  I know, I know, just bear with me here! Some, say 20% of them, are just long, straight pieces, and the rest are connected and criss-crossed.  Where they are crossed, the string is too thick for me to cut to the two inch length I want with the crappy pair of scissors I have, so I cut all of the two inch pieces that I can, and leave the rest.  Boom! You have fermentable sugar and non-fermentable sugar!

There are plenty of other enzymes present in barley, and by step mashing, you can include all of them.  The benefits of step mashing are mostly for less modified malts, such as pilsner malt (see our article on Homebrewing Belgian Style Beer for a more in depth look at the benefits of step mashing pilsner malt).  In this day and age, the vast majority of the base malt that we have access to is highly modified and awesome, so it’s not the big concern that it used to be.  Also, many homebrew systems aren’t set up to easily do temperature steps, so it’s often easier to do a single infusion mash.

Courtesy of one of my favorite BYO articles, The Science of Step Mashing, I re-created the below table to give you an overview of enzymes and optimal temperature ranges.


Optimal Temperature Range

Maximize the Enzyme



86° - 128° F

95° F

140° F


95° - 131° F

113° F

140° F


113° - 128° F

122° F

145° F


122° - 138° F

136° F

155° F


130° - 150° F

148° F

160° F


150° - 160° F

158° F

170° F

This simple table has helped me literally hundreds of times when designing a mash or trying to understand better the available enzymes and temperatures that are activated during the mashing process.


Enough Science!  Let’s Get Down To Process!

As we all know, process is important.  It doesn’t necessarily matter HOW you mash, as long as you’re following the science and making the sugars that you want for the beer that you’re trying to make.  My first mash tun was an igloo cooler with a bag in it as a false bottom, and although I’m sure the first couple of beers it produced were horrid, it was probably due more to my own poor recipe formulation skills and less to the equipment.

First and foremost, you need to know what you’re trying to make before you dough in, so you’ll want a good beer recipe.  Are you making a pale ale? A pilsner so full of saaz hops and lager yeast that the Czech Republic will beg you for your recipe?  All of these beers will have different mash temperatures, so you will need to decide what the best mash temp will be.

Mash Sludge

On our system (we currently use the Robobrew for recipe kit formulation and testing), we usually heat the water to about 6° F above the actual mash temp.  You are going to cool the mash water down when you add your grain in, both because of the thermal mass of the grain itself, and because you are actively agitating it to ensure that you don’t have any dough balls.  This temperature loss is going to vary between brewing equipment and brewing conditions, so you may have to brew a few times to get yours just right. You can also easily calculate it brew day to brew day pretty closely by using brewing apps like Beersmith and a good thermometer.

Once you’ve doughed in and you’re performing your chosen mash rest, you’ll probably notice over the course of the mash if you’re not recirculating that your temperature readings are different on the top and bottom of the mash bed.  This is because over the course of a mash, the heat stratifies, which is just a fancy way of saying that the heat rises inside the vessel. Take your readings from the center, and don’t worry about it too much. Unless you are recirculating with a heating source or constantly stirring, there’s nothing you can do about it except for upgrading to a RIMS or HERMS system to recirculate and regulate the temperature digitally.  

Clear Wort Vorlauf

When you get to the end of your mash, you are going to need to set the grain bed. This is called a vorlauf, and is very important no matter how you decide to sparge.  If you are not using a pump, this process is simply opening the ball valve on your mash tun and filling a vessel, like a standard beer pitcher, then slowly and evenly pouring it back over the top of the mash until the wort comes out crystal clear.  Well, clear in that there are no more flecks of grain. Sometimes this happens in a half of a pitcher, sometimes it take ten. Be vigilant and don’t rush it! You want to leave behind everything but the wort. Remember to open the ball valve all the way during this process, because otherwise you won’t get the full weight of the liquid forcing the grain to form a grain bed, and you’ll be there forever.

If you are using a pump, it’s quite the opposite.  Since a brewing pump is pulling with some reasonable force, you’ll want to ramp it down (on the out side of the pump, definitely not on the supply side) so you don’t compact your grain bed, which is surprisingly easy to do! 

Gravity Sparge Old School Style

Now We Sparge

All sparging, or lautering, really is is washing the grain with warm water get all of the sugar that you just created into the boil kettle.  There are two basic ways to do it, and another million small modifications that may differ system to system.

The first way, and one of the most common, is called a Fly Sparge or Continuous Sparge.  With this method, generally performed with the aid of gravity, you are putting warm water on the top of the grain bed at the same rate that you are allowing wort out at the bottom via the ball valve on the mash tun.  One thing that is often overlooked is that this method NEEDS to take at least an hour, if not an hour and fifteen minutes. This method is slow and steady and should not be hurried if you want to keep your efficiency numbers up.

Heat your sparge water to at least 180° F.  The reason for this is that by the time it sits for an hour and fifteen minutes, you’ll finally have the temperature of the mash up to 168° F or so, and that extra heat helps the sugar dissolve into solution and be taken with the wort to the boil kettle.  The goal is always to have the temp of the grain and wort in the mash tun at or around 168° F, not the water you’re using to wash it.

The second way, and one of my favorites, is a batch sparge.  You can do this either by gravity or a pump, and it’s simple and quick without sacrificing efficiency if done properly.  

First, simply drain your entire mash volume into the boil kettle and get the fire rolling to start the boiling process. Take your volume of sparge water and cut it into 2 or 3 parts.  You can do a single batch, but efficiency will suffer.  I recommend doing at least a double batch, and have had a lot of luck with a triple batch. For water calculations to make your life and brew day infinitely easier, check out our All-Grain Pocket Guide.  

Take your first batch of sparge water and put it right back on top.  For the gravity version of this process, I usually heat the water to at least 180° F, if not a bit higher.  If using a pump for this method, remember that the water in your hot liquor tank needs to be at a boil, or very close to it. It will be around 180° F by the time it travels through hoses and the pump and hits your wort.  Once you have your water in, mix everything back up. Destroy that pretty grain bed you just created, and make sure all of the grain is good and wet. Some people like to let this sit for 15 minutes or so, but I never bother, especially if I’m going to wash it two more times.  I figure conversion is already done, so all I’m doing is losing heat.

After you mix everything back up, re-set the grain bed with another good vorlauf. Once it runs clear, drain it into your boil kettle again. Follow this process with the rest of your sparge water, one or two more times, and that’s it!  It’s fast, easy, and crazy efficient!

Igloo Cooler Vorlauf

Equipment Do’s and Don’t In The Mash

A good mashing vessel will help you hold your mash temperature for the duration of the mash, usually 60 minutes for a standard, single infusion mash.  Modified coolers are a great answer to this problem, losing only a degree or two during the mash, and even that only on a really cold day. More modified vessels, such as the SS Brewtech InfuSsion Mash Tuns, use the same principle of heavy insulation without the capability of direct heating, but engineer them to be better suited to the brew house and easier to clean.  And they’re made of pretty, shiny stainless steel!

Some mashing vessels, such as defunct and legally acquired modified half barrel kegs, or the BrewBuilt Mash Tuns allow you to actually heat your mash water directly in the same vessel, making them less prone to heat loss when you add your mash water.

No matter what vessel you choose, the thermal mass of the grain will go a long way towards helping you keep your temperature.  You can always keep some boiling water at hand if you need to make last minute temperature adjustments.

The really important part of a good mashing vessel is the false bottom.  A good false bottom will make or break you when it’s time to vorlauf, sparge and transfer to the boil kettle.  It needs to be the right shape for the vessel that you’re using to avoid channeling and leaving behind fermentable sugar (although this is less of a problem if you batch sparge), and strong enough to withstand the weight of the grain and pressure of the liquid as you pull it out.

If you can, choose a false bottom that is hard piped, meaning no hose connections between the false bottom and ball valve in the grain bed.  You want to make sure that all of that weight and pressure doesn’t collapse a flimsy hose and make for the worst mash ever.

If you do have a stuck mash due to equipment failure, there’s no easy way to fix it. The easiest way I’ve found, and trust me, it’s still an absolute pain, is to use the biggest brewing bag you’ve got, and put it into a bucket, the kettle, or a backup mash tun and pour your entire mash into it.  You can then fix your equipment, and hopefully try again!

The most important part of mashing and sparging, first and foremost, is that you're having fun!  Your process will change to accommodate your equipment, but the actual science behind it won't change.  Make sure that you get to know your system by brewing on it often, and figure out how the process works best in your own head.  That is the beauty, and key, to homebrewing!

Thank you for reading!  Feel free to leave comments, questions, and bad jokes as you see fit below!  Brew On!

Pertinent References

The Theory of Mashing -

The Science of Step Mashing -

Understanding Enzymes -
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AJ - August 31, 2020

I have been switching it up lately to see what I like and what I don’t like, I started off with the single infusion – single batch sparge and used that for a while. Then, I decided to split the sparge to see if anything changed. Efficiency went up a little. Then I built a fly sparge contraption and decided to give that a shot. Efficiency went up again, but I felt like I was losing too much heat with the tun lid off for an hour and the temp of the grain bed was a little low. I’m looking at direct heat step mash now in my boil kettle figuring that I can transfer to the mash tun for lautering and sparging. I also like the idea of decoction, but only for specialized styles, not every brewday… Tweaking the process is part of the fun.

Tyler - December 21, 2018

Definitely gets me thinking about my efficiency numbers and my fly sparging process. It doesn’t take me nearly an hour to complete my fly sparge and sounds a little daunting to add that much more time into my brew day but that may be why I’m a little low on efficiency. I have never batch sparged before but that sounds pretty enticing. My system is a gravity system with 2 igloo coolers and only one burner. Thinking about how the batch sparge would work for me. Maybe add near boiling water to my hot liquor tank just before I empty the first round of mash? Anyway, thanks for the info and science lesson.

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