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Reiterated mashing

Anyone have experience with REITERATED MASHING? Been doing some research and was considering doing it for an Imperial Stout I’m making for next years Xmas gifts for friends.
I’m using 22.25 lbs of grains and was going to split the grains in half. Mash as usual with the first mash and then add 150DF water until I reach 1 gal over my pre boil vol. Run that volume into a kettle.

Mash in with the second half of the grains into that kettle and heat until I reach my mash temp; then hold for an hour. Then dump that back into my mash tun and recirculate and vorlof back into (clean) boil kettle.

Does that sound about right?
Is there still a need to lower my efficiency when using this mash technique being that I’m not actually using all 22 lbs in a single mash tun?

Or… lower my grain bill and fit it into one mash tun. Add DME as needed later in the boil to reach my desired gravity…AKA CHEATING

Any advise will help.

I’ve never heard of reiterated mashing until now. I’ve heard of partigyle mashing (might be something your interested in depending on what you have in mind).

Your process seems right from what I read. A quick mash at 150°, quick sparge. Let that rest while you mash in your BK with the additional grain, keeping the temps low to aud in fermentability. After 60-90 mins dump that back into your MT, and then sparge again. LONG DAY!

Obviously adding DME at the end is much easier. It happens a lot more than what you think, in both the homebrew world as well as the commercial world.

Edit: did you read this from BYO.

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No shame in extract. I used some Maris Otter LME in my barleywine. Easier than planning around crummy efficiency for my system at its limits.

Sounds like alot of extra work. I probably would simultaneously mash one in the tun as normal wash out a cooler and just biab the grains I couldn’t fit in the mash tun then mix them. If your system is to small for 22 lbs of grain which I assume is what your worried about make a smaller batch. Another way that I used to do is make a real thick mash then double sparge and mix all three runnings together for the boil.

I’ve done reiterative mashing a couple times. First try made a SMaSH imperial pilsner (11% ABV), and then made a “dobble” barley wine (as described by Randy Mosher in “Radical Brewing”).

The process you’ve outlined will work fine, but you will need to calculate in lower efficiency - you will be leaving about 25% of your extracted sugars in the mash tun with the grains, as opposed to the 6-9% or so that is typical for batch sparging or the 5% or so for fly sparging.
You can increase your efficiency - a lot - by modifying what you do as follows (assuming you are fly sparging):

  1. mash as per normal with 1/2 the grain and hold for one hour.
  2. sparge into a first kettle until you collect the amount of water you will need for your second dough-in (should be the same volume as you used for your first dough-in). Heat this to strike temperature.
  3. continue sparging into a second kettle until the total volume equals your boil vol.
  4. clean out your mash tun, add the remaining grains, dough in with the wort from the first kettle. Hold for one hour.
  5. Sparge into your now clean first kettle, using the runnings from the second kettle as the mash level gets low.
  6. After you run out of liquid in the second kettle, continue sparge adding 150F water until you reach your pre-boil volume.
  7. Boil and process as normal.

Note, this will give better efficiency than what you wrote, but it will still be lower than you are used to getting for a single mash. That’s the basic trade-off for this method. Higher gravity for lower efficiency.

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How do you like reiterated mashing as opposed to adding DME or other forms of sugar? The extra work for me is fine when I do it a time or two a year. It sounds like this method would allow you to use your existing equipment, but still have a truly “All Grain” beer.

Yeah one of the sources came from BYO. There were a few places I’ve read about it, but the bulk of info came from BYO.

I’ll bet ya $50 that if you supplement with DME no one will be able to tell the difference…

Sure seems sooo much work… The main, or perhaps the only reason stuff was done like this years ago was, 1, under modified malt, 2, thermometers and temperatures weren’t available/understood. It seems your doing a throw back style. Not hammering on you, just saying, the way things are done with all we have to avail, is probably as good as it will get… There aren’t any methods that will push brewing over the top. Sneezles61

Hahaha your probably right.

Yeah I’m more or less interested in doing it for the experience at this point. I’ll post how it turned out

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I did what I called a ‘split mash’ for a bock back on 12/31, Regular mash and sparge with 1/2 the grains, then took that wort to use as the liquor for the 2nd 1/2 of the grain bill. 1st mash was at 147, 2nd mash started at 147, then did a decoction up to 157 for 20 minutes.
It did increase my mash efficiency by 15% (from 53% to 68%) over my previous bock with the same grain bill, but it also increased my total mash time from 75 minutes(with a decoction) to 147 minutes. Worth it? Adding DME is ALOT quicker. We’ll see how the bock turns out.

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I have this weakness that when I read about some old, obsolete technique and I have the means to do it, I want to try it out. I did a clone of Pilsner Urquell a few years ago using the original process - undermodified malt, 4 hour quadruple decoction, 4 hour boil. I’ve played around with Turbid mashing, and one time helped brew a Sahti in a wood-fired sauna using a hollowed-out log (kuurna) lined with straw and juniper twigs as a sparge vessel.

It’s about the experience, more than the results. There is a reason these techniques are no longer widely used. But by doing them, it does give me a much better feel for what works and what doesn’t, which gives me more options when I decide to do something that is outside the box.

So I would encourage you to give it a try, but don’t expect to adopt it for typical use. Simply adding DME is MUCH easier and faster.

Still looking forward to someday finding a wooden tub I can use for doing a stone brew (boil using red hot rocks dropped into the wort as a heat source).


I thought about using the hot rock method but not for the whole mash process but to give it a smokey character


Well, did it take way longer… yes
Was my wife ready to kill me after… well, yes
Did I reach my estimated OG of 1.105… yes!

I can say that today was a huge success and I learned a lot. Splitting my 24.5 lb grain bill in half, mashing 12.25 lbs with 4 gal of water. After 30 minutes, topping it off with an additional 5 gal of 150DF water. Run that off into a kettle while emptying the mash tun. Refill the MT with the other dry grains and stike with the wort from the first mash. Let set for 1 hr and continue as normal.

I was able to use my existing 10 gallon pots and mash tun to mash 24.5 lbs of grain to come out with 1.105! Now the real test… see if my two step starter of WLP007 has what it takes!!!

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Maybe I’m too late, but with a brew that big, I like to retain some of the yeast and have another starter, if you will, about a week into it to help revive the original pitching… Sneezles61

Oh ok, yeah I dumped it all in, but maybe I’ll add some yeast nutrient(Fermaid K) to primary?

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