Another Stuck Fermentation Question!

[belmontbrew]

This might be my first stuck fermentation! Or, something else. Here's my situation.

Grain Bill: Partial Mash Oatmeal Stout, based on Jamil's all-grain recipe.
6 lb Light LME (Morebeer)
1 lb 2-row
1 lb Flaked Oats (totally unprocessed by me)
0.75 lb Chocolate Malt
0.75 lb Victory Malt
0.5 lb Crystal 80
0.5 lb Roasted Barley

I did a 60 minute mash, but had some temperature problems. My temp hit 168 at one point, likely with hotspots that went over 170.

Post-boil OG: 1.052 (measured by refractometer and consistent with readings taken during the mash)

5 gallons went into the fermenter. I've been using a chest freezer for the last few brews, on "manual control". This is the first time I've used my new eBay controller. Temp set at 62F, with a 1F tolerance.

Yeast: WLP 004, no starter

Took gravity readings every 24 hours, and tracked the gravity down to 1.025 (by refractometer) by the fourth day. Since then, no change. The wort is getting clearer, there's no visible krausen or bubbles, and it looks like the yeast decided to pack up their things and head for the bottom.

So, is this a stuck fermentation, or did I wind up just creating a super high bodied beer? When I taste a sample, it does not taste as sweet as the gravity would indicate. To me, it tastes like it's done.

I tried shaking up the bucket twice, a day apart. Still no change in gravity.

Oh, and I'm using BrewPal to do the refractomer to gravity conversions. My refractometer was calibrated at some point in the past, and is still in-cal today.

Any advice?

Thanks!

 

[Dunerunner]

Warm it up, or let it ferment a week longer. Optimum temp for that yeast is 66, and an expected attenuation of 74% on the high side, 69 on the low...so looks like the yeast did its job.

 

[belmontbrew]

I forgot to mention, I did let it start to rise a few days ago. It's now at 68-69, with no change.

Regarding the yeast efficiency, Brewpal and the original recipe said to expect an OG of 1.056 and an FG of 1.016 (71% efficiency). Even if I get 69% from 1.052, that should still be about 1.016, shouldn't it?

 

[Dunerunner]

Rouse the yeast, shake the fermenter. And yes, you're right about the efficiency, just sounds like the yeast may have quit early.

 

[MikeinCT]

While doing an all grain mash my temperatures once went too high. The result was an experience like yours. I ended with a high FG. When it did not move lower after a few days I bottled. The beer was surprisingly good. I think high mash temperature will yield extra unfermentables.

So good luck, Mike

 

[belmontbrew]

Followup: I bottled today after nearly three weeks in primary. Flat and warm-ish, this beer tastes amazing! It's got a fair bit of sweetness, but less than I was expecting given the gravity readings. It's a smooth, sweet stout with really nice body.

It's weird... I tried three batches of milds that all came out thin, and all the while I just had to screw up my mash to get a full-bodied, low alcohol beer!

 

[Germelli1]

My bet is the use of a refractometer after fermentation has started. Even with their "correction" conversions, they are notoriously in accurate once alcohol is present!