Not Complete Fermentation

[Bradyj23]

I am having trouble with a stout recipe and I need some help. I have made a coffee milk stout 3 separate times and have failed to achieve complete fermentation each time. My recipe is below.

OG:1.070
FG: 1.020
ABV: 6.2%
IBU: 40
SRM: 47

Grain:
9 lbs US Pale Malt (2-Row)
1 lbs Flaked Barley
1 lbs Carmel/Crystal-40L
1 lbs UK Chocolate Malt
.5 lbs UK Roasted Barley
.5 lbs Carafa III
1 lbs Lactose

Mash:
60 min @ 156 degrees F
10 min @ 168 degrees F

Boil:
.85 oz US Magnum (14.0%AA) @ 60
.15 oz US Magnum (14.0%AA) @ 5

Fermentation: American Ale or SO-5
14 days @ 66 degrees F
7 days w/ Cold Steeped Coffee (4 oz total, steeped for 24 hours)

The 3 times I have tried it I have ended up with a 1.025, 1.031, and a 1.033. My OG has been close each time at 1.065-1.069. I put the lactose into my boil at 15 minutes remaining. Is that the correct time? Am I mashing too high at 156 and getting too many non fermentable sugars? Any help would be much appreciated. The beer tastes good but I know it can be better as it is a little sweet. I have not done a yeast starter either. But that is the next step. Any help would be appreciated. Thanks!

Here is a link to the recipe I have been copying.
http://michiganhomebrewer.blogspot.com/2014/11/cappucino-stout-coffee-milk-stout.html

 

[specharka]

30% adjunct and high mash temperatures will do that to you. If you are seriously interested in hitting that FG, consider dropping the lactose entirely...that's contributing 8+ points in itself. Also, make a 2L yeast starter or use two satchets of dry yeast and rehydrate the yeast prior to pitching.

 

[flars]

156°F is a high mash temperature. This could be the problem with the high FG. Does the beer taste more overly sweet than it should or just have a very good body? Do you use a hydrometer or refractometer for FG?

 

[Bradyj23]

Thanks for the input. I might try the starter next time. I use a hydrometer for OG and FG. I also use a fermentation chamber to keep the temp consistent. It has a very good body but tastes sweet. I havent added the coffee yet but that brings the sweetness down. Should I try mashing closer to 150? Anything else that I am doing wrong? Thanks for the input.

 

[flars]

Taking the mash temperature down to 150°F will probably take care of the sweet taste and still retain the body.