Help with Imperial Stout

[kevinb]

I brewed an Extract recipe for an Imperial stout. The target starting and final gravities were 1.115 and 1.028. I pitched two packs of US-05. The final gravity is stuck at about 1.035. I thought this way a bit high for an imperial stout so I pitched some Red star champagne yeast to try to get it to ferment further. It did not seem to do much. Fermentation temp is about 68°F. Any thoughts would be appreciated.

 

[fantomlord]

you're probably done. how long did it ferment before you added the champagne yeast?

what was your recipe, and how/when did you add your extract?

 

[kevinb]

About two weeks before the champagne

The fermentables I used are attached

 

[kevinb]

bump

 

[TastyAdventure]

67% attenuation. That's a shame. I guess I would raise to 70 F, rouse the yeast a bit... I've never had problems with stuck ferm

 

[Yooper]

If your gravities are correct, that means the beer is over 13%! I don't know of any yeast strain for beer besides S05 that would handle that. I'm surprised it went that low, actually, but S05 seems to have done it.

I doubt it will go any lower no matter what you do. That's a monster OG.

 

[TastyAdventure]

I get 10.5% ABV in my calc. 1.115 to 1.035...

 

[TNGabe]

I get 12% using the 'alternate' high grav formula on brewers friend. Three different calcs, three different abvs. Guess that's why it's estimated abv.

OP: Although widely held, the belief that champagne yeast will dry out a beer is largely incorrect. Wine yeast can only ferment simple sugars and if the beer hasn't stalled out at very close to the starting gravity, the beer yeast has fermented all the simple sugars and left only the longer chain sugars that wine yeast can't ferment.

1.115 to 1.035 with a partial mash is very impressive.

 

[Calder]

3 lbs of specialty grains gives a lot of unfermentable sugars. If you took them out of the equation, your yeast would probably be 75% or better attenuation. I think you are done.

My guess is the specialty grains contributed about .010 in unfermentable sugars. If you take that away from the OG and FG, you have 1.105 to 1.025, which is greater than 75% attenuation.

 

[clone63]

Can you get WLP099?
It could be worth a shot if the cost is negligible to you, but as others have said, I kinda suspect anything fermentable is gone.