Do you think it has more to do with the type of malt or the mash temperature or something else?
So to report back:
I set 1084 at 59-60 ambient for about 4 days until fermentation started to slow. I then moved to 67 ambient for 4 days in hopes that it would finish up and clean up. I then put it back at 59-60 for 6 more days until I had a free Keg to rack it to. Racked today.
Taste was pure stout, dry with roast up front, showing more chocolate as the sample warmed. Though I'm no Cicerone, there was no diacetyl that I could detect.
I only got 63% attenuation. Hmmm. Maybe 59-60 ambient was too cold? Maybe it just wasn't a fermentable enough wort? My guess would be the wort, mainly. But probably a combination. Mash was 152.
Taste was very promising though, so I still believe this will be a good beer. Maybe just an Irish Stout instead of an Irish Extra Stout.
I would guess your temps were a bit on the cool side, with the ideal range for that yeast being 62F - 72F. But you stated ambient...what was the actual temp of the beer? It is our experience that the fermenting beer will be 5 to 8 degrees warmer than the ambient temps.
We just love our new conical fermenters with thermowells!
No idea what the actual fermenting beer temp was. For a 2.5 gal batch, I will assume a few degrees warmer than ambient which would put it in the useful, low estery range for 1084.
The reason I believe the low attenuation has more to do with the wort is that I find I get on average 10% less attenuation with my darker beers (porters and stouts) than I will get with lighter styles, regardless of yeast or temperature (a whole other topic!). Still, 63% was the lowest I ever got with any beer, dark or otherwise, so this time there might be more to it than just the wort.
I agree with you. I find attenuation is much more dependent on wort than yeast.
I have been having rather poor attenuation issues lately with all different styles of beer and all different yeasts, both dry and liquid.
Type of malt, yeah, if you're talking crystal capable malt or something similar. But that's part of the overall recipe design, which is what I really mean. Mash temp has a minor effect, but not as much as it used to.