Imperial Stout Advice

Greetings fellow brewers.

I am looking for some feedback on an imperial stout recipe I intend to brew this week.

12 lbs                Pale Malt, Maris Otter (Thomas Fawcett)        Grain            80.0 %       
1 lbs 4.0 oz          Chocolate Malt (Simpsons) (430.0 SRM)      Grain            8.3 %       
1 lbs 4.0 oz          Roasted Barley (Crisp) (695.0 SRM)            Grain            8.3 %       
8.0 oz                Barley, Flaked (Thomas Fawcett) (2.0 SRM    Grain            3.3 %       
1.00 oz              Warrior [15.00 %] - Boil 60.0 min                Hop              48.6 IBUs   
0.50 oz              Magnum [12.30 %] - Boil 60.0 min              Hop              19.9 IBUs   
2.00 oz              Goldings, East Kent [5.00 %] - Boil 20.0      Hop              19.6 IBUs 
1.0 pkg              Scottish Ale (Wyeast Labs #1728) [124.21  Yeast

It will be a 4 gal batch to make sure I have enough room in the MLT.  I typically use Magnum as my bittering hop and have 0.5 oz from a previous recipe - that’s why I have two bittering hops.  I like Warrior too and appreciate the high AA for this big of a beer.

Some additional details are:
Estimated OG: 1.100 SG
Estimated Color: 78.1 SRM
Estimated IBU: 88.1 IBUs
Estimated FG: 1.025 SG

I will do a single infusion mash at 154F for 60 minutes with a water/grain ratio of 1.5.  I will boil for 60 minutes.  If the gravity is too low, I will add some DME to boost the wort.  Chill and ferment in the low 60Fs until the yeast slows down and then allow it to rise to upper 60s.

Any suggestions, comments or criticisms?  Thanks folks.

Biggest question is what about the yeast? Are you doing a starter? One package of liquid yeast will be severely under pitching.

Yes, I will definitely do a starter.  On a stir plate.  And pitch with plenty of O2.

big starter. you are going to want like a 2 or 3 liter starter. either step it up or consider a batch of ordinary bitter to grow your yeast up first.

Yes, great idea.  I will step it up.  Thanks.

Looks like a solid recipe.

Thanks Keith.

And true to my philosophy, I will have beer at the end of recipe.

Personally I would mash lower. 17% of the grain bill is highly modified malts. You’re already asking 75% attenuation of the yeast. You’re not going to have a problem with finishing too low on a beer like this. I typically mash at 149 for all my big imperial beers and I’m yet to have an over-attenuation issue.

+1. Same here. I mash RIS, Barleywines, Quad, etc. @ ~ 149. Never over attenuated. There’s still a ton of malt character left.

+2 - I’ve never tasted a really big beer and said “that’s too dry”. The opposite, sadly, happens far too often.

I would agree with the lower mash temperature. I also add 5-10% simple sugars to such big beers
I think you should be looking for a final gravity 1016-1018. The sugar will help with this.
I would also mash longer, 2 hrs minimum…again this will help you get a more fermentable wort.

Good you are doing a starter. I like the recipe - it is similar to one that I did and not too complicated. Actually the one I did was Drew’s ‘Saint’s Go Marching In’ RIS from Zymurgy (Sept/Oct 2010). It was mashed at 153 and I didn’t think it was underattenuated at all. If anything I wish it had a little more body.

The krausen also exploded all over the room during fermentation. I used 2 packs of S-04 per 5 gallons at 64F and the krausen overflowed 1.5 gallons of headspace and 3/4 of headspace in the bucket my blowoff tube was in and I wound up with ~1/2 gallon of RIS on the floor. Messy!

Not sure if you’ve made a beer this big before, but efficiency tends to drop with higher OG. You said you can add DME, which certainly works. You could also sparge with extra water to rinse extra sugars and increase your boil to 90 minutes to boil off the extra water.  Or you could do a second runoff and get a few gallons of smaller beer.

Great advice.  Thanks folks!

I will drop mash a bit to 151F and extend for 90 minutes.  I will also sparge with a little more water (maybe a 2nd sparge) to make sure I extract as much as possible.

Thanks again for the feedback.  This is exactly what I hoped for!