S-04 oatmeal stout - high F.G. ?

[Jogurt]

Hi all !
I would very much appreciate your opinions on what to do in this situation.

Last week I brewed and oatmeal stout according to this grain bill:

66% 9 lbs. Pale Ale Malt
12% 1.5 lbs Chocolate Malt
15% 2 lbs Flaked Oats
7% 1 lbs Caramunich
(weights approximate)

I mashed at 70°C~158°F for 90 minutes.
O.G. 1.062 perfectly according to expectations.
Pitched a pack of dry Safale S-04

After 4 days at 17°C~63°F, gravity reading said 1.030
I raised the temperature of environment from to 23°C~73°F (do not ask why)
After 3 more days, gravity reading says STILL 1.030

Which means stable gravity of 1.030 for 3 days straight. But something is wrong here. During days 5 and 6 I had clear signs of fermentation. That means the gravity should be down by at least a few points. When I open the fermentor I see some bubbles coming up every now and then. The hydrometer is calibrated properly, maybe a 1-2 points off at room temperature.

I planned to bottle at cca 1.020 without priming sugar, but what now? My readings are either off for unknown reasons, or the beer is messing with me and pulling off a "still fermenting" act.

By taste I can clearly sense some sugars there, but are they fermentable or non-fermentable, who can say? The beer has wonderful balance now and really nice roasted, dark chocolate flavors with just right hop bitterness, so I do not want to screw something, like producing bottle bombs

 

[mbobhat]

If it were me, I would wait another week and then check, just to be sure. You could give it a swirl if you think the yeast has dropped out too early. I know people who like to ferment quickly, but I don't see the point if it gets better with age, why not let it get good for 3 wks and then bottle. Less cloudiness, less off-flavors (fermentation byproducts), less chance to rush into ruining your batch. It could be 1.030 FG, but why take the chance, when you can wait and eliminate that variable.

Sorry for the rant.

Hate to say it but RDWHAHB

 

[Jogurt]

Yeah that is what I will probably do. Even though my last homebrew went wrong, it is still drinkable and occupies some useful flip-top bottles

But I still do not understand how can I have ongoing fermentation and stable gravity at the same time :-/

 

[g-star]

You mashed very high, had 1/3 unfermentables, fermented cool, and used a low attenuating yeast. It's done.

The bubbling could be from off-gassing as you increased the temperature. If the gravity isn't moving, it's not fermenting anymore.

 

[Jogurt]

I used this recipe as a base http://beerrecipes.org/showrecipe.php?recipeid=1209
So I just guessed I could get similar numbers as that guy. I even deliberately lowered the recipe to O.G. 1062

Quick search told me that these yeasts (S-04 and Wyeast 1084) should get similar attenuation, or am I wrong?

 

[WoodlandBrew]

Agreed with g-star.

You will probably find this relevant and interesting:
http://woodlandbrew.blogspot.com/2013/01/mash-temperature-theory.html

And that information in practice
http://woodlandbrew.blogspot.com/2013/01/measured-mash-temperature-effects.html

 

[WoodlandBrew]

deleted duplicate post

 

[Jogurt]

It would seem that combining the two articles into calculation is scary effective

After 158°F 90min mash, I should end up with ~20% unfermentables
From 1.062 that is about 0.0124, which leaves 0.0496 fermentables

Using your rule of thumb the S-04 attenuation could be down from 70-75% to 63-68%
Which means F.G. could be 1.028 - 1.031
That seems to work...

Only I am not sure if that is not counting the same thing twice. In which case I would still be a bit high.

 

[WoodlandBrew]

Oh good. I'm glad it works for you.