Traditional German Brewday

Last week I asked reddit their opinion on brewing a maibock. Mai have been a bad idea. I ended up doing a decoction an then just for fun I chose to follow the Reinheitsgebot. Having never done a decoction I learned a few valuable lessons.

  • Manual decoction calculations are hard
  • Decoction smells amazing
  • Decoctions sputter and burn you. Gloves required
  • Kettle scorches suck
  • Decoction has an impact on the beer. Naysayers be damned!
  • Fortified my opinion that charcuterie boards are essential for brewing

Recipe and Process


Tap. Following the Reinheitsgebot does not allow for acids and brewing salts. That being said here is my horrible tap water.

  • Calcium: 82
  • Magnesium: 46 (this is why I usually cut with distilled water)
  • Sodium: 26
  • Chloride: 82
  • Sulfate: 66
  • Alkalinity: 210
  • pH: ~8

Aside from the shitty Magnesium content this profile is fairly close to Düsseldorf water. Perfect for Altbier so I figured it should make a palatable Maibock.

Mash pH was adjusted with Acidulated Malt to ~5.5.


  • 56.4% Weyermann Floor-malted Bohemian Pilsner Malt
  • 28.3% Weyermann Vienna Malt
  • 5.4% Weyermann CaraHell
  • 5.4% Weyermann CaraMunich I
  • 3.5% Weyermann Acidulated Malt
  • 1% Weyermann Melanoidin Malt


Here is where things get fun.

Start by heating up your carefully measured volume (1.5 qt/lbs) of water to strike temp. Infuse to get a temp of 97F. Rest for 20 min. Pull off your calculated thick mash amount and begin to heat. Do not stir much because kettle scotches/caramelization is awesome right?  Stir and feel the sugars stuck to the bottom and curse loudly 3-4 times. Once decoction pull has reached 148F rest for 15 min. Bring to a boil stirring constantly. You will notice now that the kettle scorch/caramelization has somehow been lifted off. I chalk that up to the mash pH. When the grain begins to boil have your hand as close to the mash as possible so that you burn your fingers when it sputters. Curse and put on some rubber lab gloves to avoid too many more burns. Boil for 15 min. Add decoction back to your mashtun. Miss temp by 10 degrees as curse again. Staggered cursing is much more effective than cursing prior to mashing. Re work your calculations to ensure the next 2 decoctions hit the right temp. Let the rest of the process go smoothly.

Decoction 1

  • Mash in 97F rest for 20 min
  • Pull decoction portion and heat to 148 then rest for 15 min
  • Boil decoction for 15 min
  • Add back to mashtun and hit 125F (target 135F)

Decoction 2

  • Rest for 5 min
  • Pull decoction portion and heat to 148 then rest for 15 min
  • Boil decoction for 5 min
  • Add back to mashtun and hit 150F (target 148F)

Decoction 3

  • Rest for 45 min
  • Pull decoction portion and Boil for 5 min
  • Add back to mashtun and hit 167F (target 168F)

Vorlauf and then fly sparge @168 to collect appropriate kettle volume.


Stir like crazy when the hot break forms. No ferm cap = easy boil over. The FWH addition helped keep that fairly in check. No boil over!

60 min total

  • FWH with 0.5 oz German Magnum 13.9% AA (20 IBU)*
  • 20 min 0.9 oz Czech Saaz 2.6% AA (4 IBU)
  • 10 min 1.1 oz Czech Saaz 2.6% AA (3 IBU)
  • Chill to 50F

Pitch Wyeast Bavarian Lager 2206 @ 1.75 million cells/ml/P

Ferment at 53F

I still have to do a diacetyl rest and then lager as cold as possible for 2 weeks.


  • OG: 1.071 (1 point higher than expected)
  • FG: N/A 1.016 expected
  • IBU: 27
  • SRM: Unknown but the decoction certainly darkened it! ~ 10
  • BU/GU: 39
  • ABV: 7.13 expected

*I calculate my IBU of FWH the same way as I do with 60 min boil additions as I find FWH calculators widely vary. YMMV.


The people of reddit do not lie. It was a day long event of 7.5 hours total including cleanup. People claim decoctions do nothing, I call BS. Aromas I have never smelled before were wafting all around my brew space. The wort was some of the best I have tasted. The colour got pretty dark! Aside from my first screw up it went well and I enjoyed doing this historical brewing method.

This coming brewday I will take things a little easier with a single hop NEIPA using Idaho 7.

This years magnum is resinous. Check out that hop nugget!


2 thoughts on “Traditional German Brewday

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