Recurring STUCK fermentation

[good_brew]

I brewed my second batch earlier this month and, for the second time, my fermentation has stalled.

First time around, I brewed a simple all-grain IPA that started out at 1.055 and finished at at a 1.033. I mashed at 153ºF. I tried to restart the fermentation with a 1L yeast starter at high krausen. It did nothing. I chalked it up to some variable I screwed up but I never did figure out what it was. It's too cloying and mostly undrinkable.

Now, I made a 5 gal. AG milk stout (OG 1.063) and it's stalled at 1.042 (checked with a refractometer, 1.026 when I double checked on my hydrometer). I infused mashed at 160ºF (for a maltier stout) and the boil was pretty weak (non-rolling), but the fermentation looked like it got pretty vigorous—beer and sediment in the airlock. I'm not sure what to do at this point.

With both beers, the boil was weak, I oxygenated pretty liberally, kept the beer at a stable 66ºF—everything but the boil looked like it was going well, so I can't figure out the issue.

Thoughts?

 

[SavoryChef]

Have you calibrated your thermometer?

 

[good_brew]

Have you calibrated your thermometer?

I have a bunch of thermometers, but I only rely on my lab thermometer for my readings.

 

[badlee]

What yeast? Did you pitch enough? Was it out of date?
Did you manage to maintain your mash temps?

 

[SteveHeff]

Just so I understand, are you using your refractometer AFTER fermentation? Due to the alcohol in the beer, you will not get an accurate reading. You have to rely on your hydrometer readings. If you're still getting higher than expected hydrometer readings, I would recommend calibrating the hydrometer in 60 or 70 degree F DI water.

 

[chickypad]

Now, I made a 5 gal. AG milk stout (OG 1.063) and it's stalled at 1.042 (checked with a refractometer, 1.026 when I double checked on my hydrometer). I infused mashed at 160ºF (for a maltier stout) and the boil was pretty weak (non-rolling), but the fermentation looked like it got pretty vigorous—beer and sediment in the airlock. I'm not sure what to do at this point.

You mashed a 1.063 stout at 160, and can I assume there is lactose in it given that it's a milk stout? I think it's probably just done at 1.026. As mentioned, a refractometer is no good without corrections in the presence of alcohol.