[Carson B]

Questions of this ilk have probably been asked over and over again, but I'm so beside myself at a batch that just went into the fermenter I thought I'd ask anyways. I made an imperial stout that was aiming for OG 1.140 for fun. This was using 15.5 pounds of grain for 2.5 gallon batch size, assuming 65% efficiency. I mashed in a 10-gallon SS Brewtech mash tun for the extra space. I hit 1.107 (50% efficiency).

RECIPE:

2-row              72%
Chocolate        10%
Caramel 120     5%
Flaked Barley    5%
Roasted Barley  3%
Caramel 60      2.5%
BlackPrinz        2.5%

I hit all the Beersmith-predicted volumes as normal for my equipment profile. The ONLY change I made in my process, which I'd not done before, was decrease mash thickness from 1.25 qt/lb to 2.00 qt/lb. I had the extra space, so I figured it'd help with efficiency. Nope. Because of the size of the grain bill, I ended up collecting enough volume pre-boil that no sparge was necessary.

I've never missed an OG by this much, as it's gotta be only possible in beers this big. I know efficiency can decrease drastically with bigger beers, but I was shocked to see it with that thin of a mash. Is this just a function of the size of the beer??

[allenhuerta]

So I'll just start with No Sparge. You can do well with that method, but some say it's typically going to hit a lower efficiency. I have not done one myself.

Second, 1.140 OG. Once you start going high, you'll also typically lose some efficiency as well. I wouldn't worry about the mash thickness change.

What you could do is plan for it and bump up the grain beforehand. Boil longer to get more evaporation - would have to think about your batch size and how much loss you actually have in this case. Or calculate huge beers at a lower efficiency. Not sure what you normally get on your system, but if I were doing that beer, I'd probably write the recipe at a lower efficiency.

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[Carson B]

So I'll just start with No Sparge. You can do well with that method, but some say it's typically going to hit a lower efficiency. I have not done one myself.

Second, 1.140 OG. Once you start going high, you'll also typically lose some efficiency as well. I wouldn't worry about the mash thickness change.

What you could do is plan for it and bump up the grain beforehand. Boil longer to get more evaporation - would have to think about your batch size and how much loss you actually have in this case. Or calculate huge beers at a lower efficiency. Not sure what you normally get on your system, but if I were doing that beer, I'd probably write the recipe at a lower efficiency.

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Thanks for the response.

I've never done no-sparge either, and this wasn't even on purpose. It just happened to match up because of the mash thickness and required pre-boil volume. At that thin of a mash, the volume run off as first-runnings was what I needed pre-boil (at least for batch volume, apparently not gravity). I can see getting slightly lower efficiency that way, but not this much, or so I thought.

I typically get 69%-ish with big beers around 1.100. I knocked it down to 65% for this one, and that clearly wasn't enough.

Considering I have no experience with no-sparge, I'm thinking the problem lies in there. Have to imagine I left a ton of sugar behind. I assume I could sparge more then boil much longer next time, but I'm not quite sure how to calculate that or how to get Beersmith to calculate it for me. I've read somewhere that typically you want to scale these to where you collect about 0.65 gallons pre-boil per pound of grain in the mash (according to the author, this is the ratio that achieves complete extraction), then boil down to the desired batch size and gravity.

[chinaski]

Any time I make big beers- I assume 50% efficiency or so and do no sparge.  So your results aren't abnormal or a problem.  Plus you've made very high gravity wort so don't sweat it.  It isn't "horrible" its imperial strength wort.

I also plan on using the second runnings for another beer to make use of that sugar that left in the mash.

[kramerog]

Check out http://braukaiser.com/wiki/index.php/Understanding_Efficiency.  The efficiency calculator in my signature line is adapted from Brau Kaiser's calculator (he did the heavy lifting).

[MattyAHA]

its still gonna be a imperial stout, so i would not worry

[joe_meadmaker]

Have you ever thought about trying the double mash technique?  I like the concept of it, but haven't ever done a beer big enough to justify the extra work.

[allenhuerta]

Have you ever thought about trying the double mash technique?  I like the concept of it, but haven't ever done a beer big enough to justify the extra work.

Reiterated mash? Or something else.

I was looking into that myself since I moved from keggles to the Foundry.

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[erockrph]

Have you ever thought about trying the double mash technique?  I like the concept of it, but haven't ever done a beer big enough to justify the extra work.

Reiterated mash? Or something else.

I was looking into that myself since I moved from keggles to the Foundry.

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It works great for huge beers. Hold mash #1 at alpha range to create dextrins, then start mash #2 at limit dextrinase temps to create a highly fermentable wort. Pitch a huge, active starter, and you should be in business.

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[joe_meadmaker]

Yep.  Mash part of the grain, first runnings back in to the pot, mash again.

Thanks for the additional info erockrph.  I hadn't seen the use of a temperature difference like that.  Or rather I don't recall seeing it before.

[Visor]

I tried it once instead of a normal double batch and never will again, mash efficiency went straight into the toilet. Did the same recipe again as a double batch and had a typical ME, don't remember the specific numbers but IIRC the iterated mash was about 20 percentage points lower than normal.

[erockrph]

I tried it once instead of a normal double batch and never will again, mash efficiency went straight into the toilet. Did the same recipe again as a double batch and had a typical ME, don't remember the specific numbers but IIRC the iterated mash was about 20 percentage points lower than normal.

How big was the beer you were brewing? I definitely see an efficiency hit compared to a normal batch, but the tradeoff is the better attenuation. For my system, its also the only way I can fit 14+ pounds of grain in a 3 gallon batch.

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[Visor]

   It had an O.G. of 1.105. After checking my notes the ME% was only about 10 points lower than the subsequently brewed batch. The real drop-off showed in the respective partigyles, the Iterated mash partigyle had an O.G. of 1.049, the one from the normal mash was 1.055. Additionally the iterated mash main brew hit 63% AA, the regular mash main brew did 79% AA.

[MerlinWerks]

This article will help explain what is going on:
https://beerandwinejournal.com/efficiency-gravity/#more-4006

Basically, as you've already noted, you need to start with more water, do a sparge and boil longer. I do BIAB and in Beersmith I just adjust my boil time to 2 - 3 hours depending on how big of a beer I'm brewing to get the total amount of mash liquor i need. Then I'll add salts and heat the total amount to the strike temperature then pull off a couple of gallons to sparge with after the initial drain. Has worked well so far, although I've never attempted any thing near 1.140