My apologies to extract brewers, but today is solely about all-grain brewing, and how we get the extract out of the mash when conversion of starch is complete. Three techniques are practiced by homebrewers, namely fly-sparging, batch-sparging, and no-sparging. In the first, hot water is sprinkled over the grain bed, while wort is run off from the bottom. In the second, wort is run off, then further water is added, and a second wort is run off, while in the third no water is added after the mash, and only the wort run off from the mash is what goes to the kettle.
As soon as I wrote that paragraph, my hackles started to rise at those three terms. They just seemed an incorrect way to describe these procedures, and another instance of brewers introducing meaningless jargon, such as “liquor” for “water,” and “knockout” for “finish.” You see, the term “sparge” has a quite precise meaning, which is to “sprinkle.” My Webster’s Dictionary is specific to brewing, for it defines it as sprinkling the mash with hot water. In short, fly-sparging is meaningless, since sparging is all we need to call it. And batch-sparging is not sparging at all, but merely re-mashing, and no-sparging is a back-formed negative term for single or dilute mashing.
Or am I merely being pedantic? I don’t think so, because there is no point in inventing new words or phrases unless they enable us to express ourselves more clearly, and I just don’t see that these new terms do that. In fact, they do the reverse by implying that all three procedures are related to sparging when only one of them is. So in what follows I shall use the terms I have described here, and desist from further pontification.
Let’s suppose you are brewing 5 gallons (19 L) of beer at an original gravity (OG) of 1.048 (11.9 °P), which would require 10 lbs. (4.5 kg.) of pale malt, since at our 65% efficiency pale malt yields 24 gravity points per lb./gallon. A normal infusion mash is carried out with about 1.25 qts. (1.2 L) of water per pound of grain, so in this case we would want 12.5 qts. (11.8 L) of water. As a rough guide, the grain will hold up to 0.1-0.125 gallon of wort per pound of grain, so in this case the holdup will be 1-1.25 gallon (3.8-4.7 L) of wort. Therefore, straight run off will give you less than 2 gallons (7.8 L) of wort, or even less if you have a significant dead volume under the run-off outlet. In other words, you have lost a third of your extract, and your expected OG will only be a maximum of 1.032 (8.1 °P) if you diluted that 2 gallons down to the brew length of 5 gallons (19 L).
So you have therefore got to do something to recover that lost one gallon (3.8 L) yield, and the obvious way to do so is to rinse out the grains with more water. You can’t do so just by adding one more gallon of water to wash it out, because there will be a partitioning of extract between the added “free” water and the wort in the grain. To get all the extract into your wort you will have to add considerably more than one gallon (3.8 L) of water; just how much is going to depend upon the method by which the water is added.
As I have mentioned above, sparging means sprinkling hot water over the grain and allowing it to trickle through the bed. This involves balancing the rate of sparging with the rate of wort run-off so that there is always an inch or so of water on top of the bed. Higher water levels will increase the pressure drop across the bed, which could pack the grains down tightly and slow the process considerably. If the bed dries out at all, it will crack open channels and the sparge water can run right through the bed without picking up any of the retained wort.
Therefore, sparging takes some attention on the part of the brewer, and some extra equipment. I have seen it done successfully with a china plate placed carefully on top of the grain bed, and the “sparge” water carefully run onto this plate from a vessel held just above the plate. However, a more common way is to use a sparge arm, which can either be made yourself, or bought from a supplier for $20-$40 depending upon the model. A sparge arm consists of a piece of tubing with a second tube at right angles to it; perforations on this latter mean that it swivels about the former when hot water passes through it. The upper tube is connected to the hot liquor tank; the valve on that is opened as you start run-off and the hot water is sprinkled gently over the bed by the rotating perforated arm.
Generally you would use an amount of sparge water up to the volume of the finished beer (5 gallons in this case). It should be at a temperature of around 170 °F (77 °C), since this will keep the bed at a reasonable temperature and the wort at a low viscosity so that the water will flow freely through the bed. Sparging in this way is quite an efficient process, as all the water has to pass from top to bottom of the bed allowing good contact between water and grain. The more slowly sparging is carried out, the better that contact will be, and many believe 1-2 hours duration to be optimal, though that does depend upon how finely the grain has been ground. For many of you that extra time on your brew day may be unacceptable, and I must say I usually only sparge for about 30 minutes.
There are some other points about sparging, the first being that the sparge water should ideally be treated (that is with whatever added salts) the same way as the mash water. If it is not, then as the sparge continues, the pH of the liquid in the tun will increase as the gravity drops and unwanted materials such as silica and tannins may be leached out into the wort. For the same reason, it is normal practice to stop sparging when the liquid from the tun has reached a specific gravity (SG) of about 1.008-1.010 (2.1-2.6 °P). By that time you should have collected 5.5-6 gallons (21-23 L) of wort, and be ready for the boil.
This is an old, traditional procedure that was widely used until the invention of sparging sometime in the early 19th century. Brewers would run off from the first mash, then re-mash with hot water, collect a second wort, then maybe mash one or two times more, to give a total of up to four worts. Often the first, or the first and second together would go to make a strong beer, while the third might make a table beer, and the fourth a small beer. We wouldn’t do a re-mash (batch sparge) that way, but would simply mash a second time after collecting the first wort.
This is obviously simpler and quicker than sparging, for it requires no extra equipment and the second mash can be run off quickly, with the spigot wide open. There are some difficulties with this approach, for you have to stir the bed and second mash water very thoroughly, which means you must recycle the first running of the wort to ensure there is no carry-over of grain particles or unconverted starch. You also have to calculate how much water to use in the second mash in order to hit your target volume of wort, which we’ll look at later. The biggest problem is that this procedure is not as efficient as sparging in removing extract from the spent grain. You may see that intuitively from the fact that, unlike sparging, not all the second mash water travels all the way through the grain bed. That may mean that you will find it difficult to reach your target OG the first time you adopt this approach. The simple remedy for this is that the next time you do a brew you add a little extra malt, 10% being a common amount for many homebrewers. However, this is a factor that militates against consistency in your brewing, if that is what you want to achieve.
The strike water for the second mash should be about the same temperature as the strike water for mashing, or about 176 °F (80 °C), and should be adjusted for mineral content as for the first mash. As stated above, this second mash water must be thoroughly mixed with the grain – any unmixed clumps of the latter will result in loss of extract. How much water you use depends on how much wort you collect from the first mash. In the example above we got 2 gallons (7.6 L) this way, so you would need to collect another 3.5-4 gallons (13-15 L), and this is what you would use in the second mash, although you should allow a little extra for any dead space below the faucet in the tun. It is probably wise to use a little more than you think you will need, and boil for a little longer if necessary, whereas you are stuck if you do not collect enough wort.
Single or dilute mash
This procedure is the oldest, simplest and quickest of the three methods, for it consists of simply collecting the wort after mashing. It is obviously very inefficient as I discussed earlier. You can improve the efficiency in several ways. The first is to use much more water in the mash, but there is a limit to this if you want to get good starch conversion and to avoid the wort being highly fermentable, leading to thin beers. So the second is to increase the amount of grain, which may take as much as 20% or more extra grain. The third is to add an infusion of water at the end of the mash before run-off. The fourth way would be to add both more grain and use a more dilute mash. Calculating the amounts of grain and water required to do this is difficult to do with any accuracy, and is beyond the scope of this article.
However, the intricacies of these calculations mean that this procedure gives quite variable results, and makes it just about impossible to brew in a consistent manner. It is also more expensive than sparging, in terms of ingredient costs, and requires more vessel space, so it may not be practical for making high gravity beers. In fact, if you are going to do more than one brew this way, you will very soon spend more money on extra ingredients than it would cost to buy a sparge arm. However, some commercial brewers do make strong beers this way by taking this first run wort, which will be at a high gravity. Some claim this gives a superior flavor, while others may simply want to make a very strong beer in a smaller batch size than their regular beers.
Sparging is the “classical” technique and consistently gives the best yields, and is very versatile in terms of making beers of different original gravities. It takes the longest time of the three methods, and requires buying a further piece of equipment. Re-mashing is quicker, but it results in lower yields, is somewhat inconsistent, and involves higher ingredient costs. Single mashing is simple to do and the quickest to carry out, but is expensive in ingredient costs, and may require a much larger mash vessel than the other two techniques.
It seems to me that if you plan to do all-grain brewing on a regular basis, then sparging is the way to go, and is my preferred choice. But your choice of method will depend upon your own preferences and circumstances. In the end, it is your beer you are brewing in your brewery, and not mine!