Benefits of Wet Milling and Grain Conditioning

Rumored to be originally popularized by traditional German breweries for more efficient lautering, grain conditioning is a simple technique that involves applying a small amount of water to a grain bill prior to milling. Over a small amount of time, this freshly applied moisture is absorbed into the husk of the grains which increases its pliability and resilience through the crushing process.

With just a few household items and common brew supplies, homebrewers can easily reproduce this traditional method to increase the likelihood of a more uniform crush, better flowing filter bed, reduced astringency, increased mash efficiency, and much more. Here’s how to do it!

The Process

1) Gather up the necessary tools and resources. (The process can be replicated using a variety of different methods and gear, but I’ve found the tools listed below to work the best!)

Mash paddle or stirring stick
• Spray bottle with mist nozzle
• Grain and Mill
• Clean water
• Large plastic bag or bucket

2) After you’ve scrounged up your equipment and ingredients, you’re almost ready to get down to business. To calculate the amount of water you’ll need, take your overall grain weight and multiply it by 2%. Moisture less than 2% will likely have little conditioning effect on the grain, and much more than 2% just becomes messy and unnecessary. Here’s a calculation example for reference:

(Grain Bill weight) X .02 = (H20 weight for conditioning)
11.25lbs X .02 = .225lbs conditioning H2O

Or for more accuracy…
5103g X .02 = 102g conditioning H2O


Now that we know how much moisture to apply for conditioning, we can fill up our spray bottle with clean water. Rather than worry about filling the spray bottle to the exact weight, I recommend filling the spray bottle completely up then taring or zeroing it on your scale. This quick trick lets you easily monitor the amount of water you’re using by periodically setting it back onto your balance and checking your negative weight.

4) After preparing your spray bottle and scale, pour your entire grain bill into a large bucket or plastic bag. A larger surface area makes it easier to apply and mix your moisture in more evenly, so try and pick a vessel or bag which gives you plenty of room. With the grain in your container, mist the top of the grain bed, then use your mash paddle or stir stick to agitate and mix the grain around. Periodically, set your spray bottle back onto your scale to monitor your water usage. Repeat misting, stirring, and weighing until you’ve hit your target weight, and the grain is consistently moistened.

5) Congrats, the hard part is over. Once you’ve applied 2% moisture, allow the grain to sit for 10-15 minutes. This permits the moisture to permeate and reabsorb into the husk material. After the hold, the husks should exhibit an almost rubbery texture. Proceed to feed your newly conditioned grains into your choice of mill and crush like normal. Feel free to check your grain after a few seconds of milling to make sure the crush looks good. The grain should look very uniform, and there should be very little grain flour or dust produced. In some cases I’ve seen my conditioned grains take up almost twice the volume of normally crushed grains due to increased hull integrity!

Shop All Grain kits

Grain that needs slightly more conditioning This grain needs a bit more water to get rid of the dry spots.

And that’s it, in five easy steps you’re able to not only reproduce a traditional technique perfected long ago, but also gain more control over your brewing process! Time to kick back, relax, and have a homebrew (or get a batch of beer brewing!).

Quick Troubleshooting

If you’re still producing a lot of grain dust and flour material during milling, feel free to apply a little more moisture and repeat the conditioning process again. Alternatively, if your mill seems to be gumming up, you can pour your grains back into your conditioning container and allow them to dry out another 15 minutes, wipe out your rollers, and crush a small of dry grain through to clean it up again.

Give grain conditioning a try with our all-grain recipe kits on your next brew day, and let us know how it goes!

Logan Cisewski is an avid homebrewer and food scientist from Southern Wisconsin. You can follow his new projects and beers on Instagram at Labrat_Experimental_Brewing.

written by Logan Cisewski

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8 comments on “Benefits of Wet Milling and Grain Conditioning”

  • Great info. Since you're exposing the rollers to water, I was wondering if using this method changes anything with respect to maintenance or longevity of the mill? I believe the rollers and all metal parts that come in contact with the grain are aluminum so rust shouldn't be an issue. Thanks!

  • I condition my grains the day before it goes in my Corona mill. I don't measure the water. I just fill the spray bottle up with RO water and spray, mix, spray, mix... etc. I use a lot of water (5+ oz for 11# of grain) and don't find it to be any harder nor messier than using a precise 2%.

  • I condition my grain and it really helped improve lautering (batch sparge). I was able decrease the mill gap to get a finer crush and faster conversion. My grain stays in suspension better during the mash instead of dropping to the bottom and compacting. I also dont need to add rice hulls to my wheat beers anymore even with up to 40% wheat in the grist. I condition the grain prior to start heating the mash water, by the time the mash water is up to temp the grain is ready for milling.

  • Hey Jon, I've been conditioning for the last 6 or so batches and haven't noticed any ill effects on my mill. I give it a wipe down and a few good spins before putting it back on the shelf. This is with a 2 roller monster mill.

    • Hey Logan - Thanks for the feedback. This sounds like a great technique, I'll have to give it a shot next brew day.

  • Salvation! I'm still learning my way around my new 10gal mash/lauter cooler and have had 3 stuck sparges in 6 batches, which turn fly sparges into slapdash batch sparges with more trub and low efficiency and god knows what kind of temperatures. Can't wait to try this approach. To Jon's comment, any decent mill should have steel rollers, and it'd be good to clean & dry them while your mash is resting. Maybe run a wet rag through the rollers and hit it with a hair dryer?

  • Water weighs 1 gram/ml, so if you have ml markings on your spray bottle, you don't need to weigh it to find out how many grams you have used, you can just use the ml scale.

  • Geoff Cunningham July 10, 2016 at 2:28 pm

    I had heard of this technique and was glad to see your article and clear instructions... however, I just tried this today and the result was not good! My efficiency went down about 9%, than with dry milling. The grain looked overall less crushed after I milled it, so I was skeptical. If I try this again - I would take "stan's" cue and decrease the gap on the mill for a finer crush (although I've never messed with that before).

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