What is double mashing, and why do we need it?

In principle, double mashing means splitting the amount of malt into two or more portions. By mashing in several rounds, you avoid mess and overfilled malt pipes.

Pros and cons of double mashing

Have you tried brewing an imperial stout, Belgian quadrupel, barley wine or other big beers that require large amounts of malt? Then you have probably experienced a troublesome brew day with an overfilled malt pipe, heavy lifting and lots of mess.

Many brewing machines have a tall and narrow design. This is what can cause problems, and it can be particularly difficult to extract as much of the sugar as you want. Sometimes the grain bill is simply too big for your particular brewing machine.

There are of course quick and easy “shortcuts” for getting around large amounts of malt, and the result can often be good. But if you want to do it properly and without compromise, double mashing is a good solution that gives you full control of what goes into your beer.

Double mashing makes the brew day a little longer, but it can make the work less strenuous. And most brewing enthusiasts will agree that the result is worth the extra care.

Keep it simple – split the mash in two

The simple method is to split the mash straight in two. To explain it simply, let's take an example where we are mashing 12 kg of malt in a brewing machine with a maximum capacity of 8 kg.

1. Instead of cramming your brewing machine/kettle full, measure out the amount of water for 6 kg of malt.
2. Mash in 6 kg of malt and leave it for the usual mash time. You do not need a mash-out here, as you want the same temperature for the second round.
3. After the mash time, lift the malt pipe and sparge with as many litres of water as there are kilos of malt. In this case, sparge with 6 litres of water. After sparging, you should end up with roughly the same amount of liquid as you started with before the mash.
4. Empty and wash the malt pipe so that it is ready to use again.
5. Mash in the second half of the malt in the wort you made in the first round, and leave it for the usual mash time again. This time you can do a mash-out if you like.
6. Sparge as usual. The rest of the brewing process continues as normal from here.

In most cases you can expect not to get as good a yield as with a normal mash using a normal amount of malt. Even so, it will be considerably better than with an overfilled malt pipe, and you get an easier brew day at the same time. Since double mashing gives you more room, you can compensate by using a little extra base malt.

If you are brewing a beer with a lot of specialty malt, we recommend using all the specialty malt in the second mash round. Also note that the wort becomes very strong and thick here, so in the second round we strongly recommend adding a handful of rice hulls to prevent the mash from becoming too compact and difficult to sparge (stuck mash).

Double mashing with the «No sparge» method

The «No sparge» method is an alternative way of double mashing. This method takes a good deal more time, but the yield is also that much better than with traditional double mashing. «No sparge» is excellent for beer styles that benefit from a very long boil. For example bock, barley wine and beer styles that do well with a bit of caramelisation.

As with traditional double mashing, the malt is split in two. We use an example in the procedure:

1. Calculate the water for the first mash round so that you end up with a little under half the maximum volume of the boil kettle. For example, if you have a kettle that is completely full at 46 litres, you can plan to end up with 20–22 litres after the first mash. Do not allow for sparge water; everything goes into the mash here.
2. Mash the first round as usual, but do not sparge the malt. Hence the name: No-sparge.
3. Chill the first-round wort and transfer it to another container. For example a fermenter or another kettle. If you brew on a HERMS, it can be transferred straight to the boil kettle.
4. Repeat the same process with fresh water and the second half of the malt.
5. When both mash rounds are finished, combine them in the boil kettle and boil until you reach the desired amount of wort. Here you can really concentrate the wort as much as you like, and get great caramelisation as well. Allow plenty of time, as the boil can easily last several hours.
6. If you want to, and still have the motivation to brew after such a long boil, it is also possible to sparge the spent grain separately. That way you can get an extra small batch of lighter beer out of it (second runnings).

Easy shortcuts to big beers

For some people, a busy everyday life leaves no time to mash and boil for hours. That should not stop you from brewing big beers. There are of course quick and easy “shortcuts” to big beers.

Spray malt and malt extract

Using spray malt and malt extract is by far the easiest method, and it does not lengthen the brew day either. Feel free to replace part of the base malt with spray malt or liquid malt extract to increase the OG (the original gravity of the beer). If you use software to build your recipe, spray malt and malt extract will usually be available as separate ingredients you can add, and it will also calculate how much you increase the OG.

You can also use dextrose or table sugar, but here it is important to remember that pure sugars tend to ferment out completely. This means you can certainly brew a strong and big beer, but it can often come across as thin or boozy, since the sugar only adds alcohol, not body or mouthfeel, to your beer.

Half batch and «no sparge»

If you want to brew strong beers but do not want to double mash or add spray malt or extract, you can compensate with half the volume. In other words, you brew half as much as you normally would. That gives you plenty of room for the malt and a strong wort, but you compensate with a smaller volume.

If large amounts of malt are still involved, «no sparge» can be an alternative. This means that you do not sparge the malt after mashing, but instead add all the water to the mash. Bear in mind, though, that mash efficiency can drop with «no sparge», since you do not rinse out all the sugar after the mash.