All-Grain Brew Day Walkthrough (III: Mashing In)


Mashing in is the mixing of water and grain. Mixing equal volumes of water and crushed malt yields a mash thickness around 1.0 qts./lb. (2.1 L/kg), depending on how loosely the grains are settled.

This is the third installment in the All-Grain Brew Day Walkthough, which started with a post on strike water preparation

Once the brewing liquor is heated and the grist is crushed, it’s time to mash in. Mashing in, or doughing in, is mixing the hot strike water with the crushed grains so they come to rest at the target mash temperature and thickness. Homebrewers have a few options when it comes to mashing in.

Mash Temperature and Thickness

Most single infusion mash recipes specify a mash temperature in the 148–162 °F (64–72 °C) range. Optionally, the mash may be heated to 168–170 °F (76–77 °C) following this for a mash out. Mash tun space for homebrewers is frequently limiting, and mash thicknesses in the 1.0–1.5 qts./lb. (2.1–3.1 L/kg) range are common, although thinner mashes [up to 2.4 qts./lb (5.0 L/kg)] are workable. A lot of moderate-bodied ales are made by mashing at 152 °F (67 °C) at 1.25 qts./lb. (2.6 L/kg). Mash times are frequently 60 minutes, although shorter times may work just as well.

The temperature of the mash is determined by the temperature of the strike water, crushed grain, and your equipment. Homebrewers can calculate their strike water temperature, or arrive at it via trial and error. As a rough rule of thumb, if your equipment and grain is that “room temperature,” heating the strike water to 11 °F (~6 °C) above your target should yield the correct mash temperature. [This assumes a mash thickness of around 1.25 qts./lb. (2.6 L/kg).]


Which Vessel?

Most homebrewers mash in their mash/lauter tun. This is convenient because, once the mash is over, you simply open a ball valve to start recirculation. However, if you are using a modified picnic cooler as a mash tun, or any other type of mash tun that is not heatable, there are some times when mashing in your kettle is the best choice.

Mashing in your kettle allows you to perform step mashes. It also allows you to heat the mash to maintain a steady temperature, stir the mash to improve extract efficiency, and heat the mash to mash out temperatures. The only downside is that you need to scoop the mash to your lauter tun when you’re done, and rinse out your kettle. Of course, if you have a heatable mash tun, you can benefit from all these things without having to transfer your mash from your kettle to your lauter tun.


Pre-Heating the Mash Vessel

Many homebrewers preheat their mash tun by filling it with water at or above their projected mash temperature. This can be a good idea if your mash tun is not heatable, or is not heated during your brewing day. This is doubly true if you are brewing outside and your equipment is cold. If your mash tun is heatable, this is not needed.


Mashing In


When mashing in, the mash will foam when it is fully hydrated.

There are at least three options for mashing in — pour hot water into the crushed grains, stir crushed grains into the hot water, or mix the two as you go. Of these options, adding water to the dry grain is the worst. This tends to wet the grain into lumps or “balls” of wet grain surrounding dry interiors. It takes a lot of stirring to break these clumps up and evenly mix the water and grains.

Stirring the grains into hot water is a better option. This wets the grains completely as they enter the water and it’s relatively easy to stir the grist in to the brewing liquor. In addition, you can add the hot strike water to the mash tun and let it sit for about 5 minutes to pre-heat the mash tun. If the temperature of the water drops too much, drain some or all of the water back your hot liquor tank and heat it again.

A third mash in option also has several benefits — adding the grains and water at the same time. If you take two “scoops” of the same volume — beer pitchers, large measuring cups, etc. — mixing one scoop of water and one scoop of crushed grain yields a mash thickness around 1.0 qt./lb. (2.1 L/kg), depending on how finely the grains settle in their scoop. As such, one option for mashing in is to alternately add a scoop of strike water followed by scoop of grain until the grain is gone. The mash can be stirred as it is slowly layered in. As you approach 2/3 to 3/4 mashed in, you can take the temperature to see how close you are to your target. If needed, you can heat your remaining strike water to a higher temperature or stir in some cold tap water to bring the temperature down. As you near being completely mashed in, the mash will be somewhat thick (around 1.0 qt./lb.  or 2.1 L/kg). As such, pour in the correct amount of strike water to hit your target mash thickness. (If you’ve heated the correct volume of strike water in your hot liquor tank, simply stir in that water once all the grains are wet.)


Mashed In

Once you are mashed in, put a lid on your mash. If you can’t add heat to your mash tun, and need to retain as much heat as possible, insulate it with blankets or other insulating materials. After 5 minutes or so, take a small sample of wort to measure your pH. Take the sample in a small cup or jar and cool the container in ice water until the sample is at room temperature. This shouldn’t take long as you only need a volume of wort large enough to submerge the pH electrode in.

The pH of the cooled sample will be approximately 0.35 higher than the actual pH at mash temperatures. (At higher temperatures, the pH of an aqueous solution decreases as more hydronium ions (H3O+) are formed from water. Note, more hydroxl ions (OH) are also released, so the overall acidy or alkalinity of the solution does not change.) In the brewing literature, it is sometimes unclear how a measurement was taken. And, in the homebrew literature, the advice on how to interpret published pH values varies. Briggs, et. al., in their book, “Brewing: Science and Practice” (2004, Woodhead) say, ”Infusion mashes are best carried out at pH 5.2–5.4 (mash temperature), and so will give cooled worts with pH values of about 5.5–5.8.”. [Ed. But see commentary in comments section.] If you are brewing a dark beer and have added carbonates to your water, don’t worry if the pH is too low initially. Keep taking the pH over the course of the mash and you will likely see the pH drift into the right zone. It takes a little while for the carbonates to neutralize acidity.

In your brewing notebook or brewing software, take a note of the volume of strike water you used, its temperature, and your initial mash temperature. (You should already have the details of the grist written down.) If you made any adjustments, note what those were. This will help you adjust your procedures, if needed, to make things go more smoothly next time.

Next up, what to do during the mash.

Related articles

A Mash In Option

Reiterated Mashing

Should You Go All-Grain?

Simple 3-Gallon All-Grain Brewing



  1. Chris, I was always under the assumption that you want your room temp mash pH to be between 5.2-5.4? Not the other way around. That’s basically what the recommendation is in Brun’ Water, and what I’ve read from other various sources. I think Martin himself has explained that too?

    • Not to steal Chris’ thunder…

      M. Brungard proscribes a range of mash pH based on recipe (from the Bru’n Water Knowledge page):
      Suggested Mashing pH Targets (room-temp measurement)
      More fermentable wort with less body
      5.3 to 5.4
      Less fermentable wort with more body
      5.4 to 5.5
      More sharpness or tartness in beer
      5.1 to 5.2
      Lighter-colored beers
      5.3 to 5.4
      Darker-colored beers
      5.4 to 5.6

      Bru’n is setup to work with room temperature mash pH measurements, accounting for pH differences between room and mash temp. More recently he proposes that for sharper hop utilization for IPAs, one should be around 5.5 at room temp based on commercial brewer feedback. Not all of the literature agrees on optimal mash pH at mash temps – and seems to change based on brewing traditions (British vs German), style and recipe. Narsiss and Balmforth specify slightly different “optimal” ranges. A recent Q&A with John Kimmish from The Alchemist claims 5.1-5.3 is required to make good ale – hard to argue with Heady Topper’s master brewer. 5.2-5.4 puts you within a reasonable window of room temp mash pH and gives room to emphasize a specific flavor nuance you might require nudging up or down, and given the lack of precision in most of the cheaper pH meters or strips – a good middle target.

    • Chris Colby says:

      Hmmm, apparently I’ve been misinformed on this. I’ve done some research and it appears that the optimal mash pH values in the professional brewing literature are given as the pH of cooled samples, not the actual pH of the solution (which makes the most sense). I need to track down an actual, primary source for this, but I’ve found enough second-hand sources that I trust and appear to be independent that I’ll accept that conclusion. I’ll fix the article to reflect this information. Thanks for your comment.

      [Edit: OK, I’ve made the changes in the main text. This is both somewhat interesting and somewhat frustrating. The chemistry itself is very straightforward — the pH of an aqueous solution does change with temperature; there’s nothing controversial about that. The question is whether the pH values reported in the brewing literature are the actual pH values or from cooled samples. Professional textbooks — at the least the ones I have — give various pH values, but don’t mention how they were measured. I’ll keep digging.]

      • Chris Colby says:

        Arrrrrrrgh! Why is there not a simple and consistent answer to this question? I just looked in Bamforth’s 2006 text, “Scientific Principles of Malting and Brewing” (American Society of Brewing Chemists) and found this:

        “The pH of the mash depends on mash temperature, and at 65 °C the pH of a mash is approximately 0.35 less than 18 °C because of dissociation of buffering substances. This difference must be considered when measuring pH and when declaring the ‘optimum pH’ for mashing events.
        Although the precise picture will depend on the nature of the grist and the mashing regimes involved, it has been shown that the highest yield of extract and highest ferment ability occur at pH 5.3–5.8 (measured at 65° C).”

        Note that 18 °C = 64 °F (roughly “room temperature”) and 65 °C = 149 °F (mash temperature)

        • From 2009 Briggs “Brewing: Science and Practice”
          “A major difficulty follows from the habit of measuring the pH of worts or mashes at
          room temperature and assuming that these values apply at higher temperatures, when they
          do not (Hopkins and Krause, 1947). Weak acids, like water (see Appendix), dissociate
          more as the temperature rises and so the pH values of their solutions fall, like the pH
          values of mashes (Table 4.8). Thus at 65 ëC (149 ëF) the pH of a wort is likely to be about
          0.35 pH unit lower than at room temperature and 0.45 lower at 78 ëC (172.4 ëF). ”

          and then

          “The pH optimum of -amylase, determined at room temperature, is
          about pH 5.3, but its optimum estimated from mashing experiments is often reported to be
          about 5.7. This error is due to the pH having been determined on the mash after it was
          cooled, when the pH had risen. Because of this difficulty the pH optima of changes
          occurring in mashes are a little uncertain (Table 4.9).”

          The confusion is acknowledged, but never seems resolved. de Clerk references pH values that can only be at room temperature, while Narziss and others are inconsistently using mash temperature references (without a temperature) and room temperature values. Taking pH measurements at mash temperatures requires lab grade equipment.

          This is a major area of confusion for home brewers – especially those with a bit of chemistry in their backgrounds who know that temperature is linked to pH. Palmer & Kandinsky seem to land squarely on the side of room temperatures in their new book – and very similar ranges as recommended by Brungard. AJ de Lange also recommends room temperature.

          • Chris Colby says:

            I think Briggs, et . al. nails it here. When he combed through the literature, pH values were taken at different temperatures, so you really need to look at each individual study and see what the researchers did. And in some cases, they may not have specified.

            He does go on to say this, “”Infusion mashes are best carried out at pH 5.2–5.4 (mash temperature), and so will give cooled worts with pH values of about 5.5–5.8.” To me, that’s the answer most homebrewers are looking for.

  2. Alexander Gashti says:

    Since FL is very hot, I’ve tended to brew my all grain batches indoors, but with an underpowered electric stove, I can not boil full volume for a 5 gallon batch. My solution to this problem is to cut the recipe in half, brew in a bag in two separate pots of equal size, and conduct the same mash and boil in both vessels. Then combine the cooled wort from each pot into the fermenter. This works well. However, one of the pots tends to come to temperature faster and does not retain the mash temperature as well as the other pot. Weird. Maybe it’s the stove, or maybe it’s the pot, but this is a solution for someone who can not brew outdoors.

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