Timing of diacetyl rest

[Simonpyman]

So this is the second time i have used the omega labs kolsch II yeast and i find myself going past the expected final gravity once i do the diacetyl rest. The recipe i created has a final gravity of 1.013 (based on the recipe creator on here) and on day 3 i am at 1.016 fermenting around 65F. I am planning to do the rest now but I expect to pass 1.013. Worst case the abv will be higher but at what is the rule of thumb when initiating the rest to reach desired final gravity?

 

[Minbari]

D-rest isnt really for getting your SG down, it is to allow the yeast to absorb off-flavours. specifically sulphurous compounds. it may reduce the SG a bit, but a little off your target shouldnt matter much.

 

[GFHomebrew]

So this is the second time i have used the omega labs kolsch II yeast and i find myself going past the expected final gravity once i do the diacetyl rest. The recipe i created has a final gravity of 1.013 (based on the recipe creator on here) and on day 3 i am at 1.016 fermenting around 65F. I am planning to do the rest now but I expect to pass 1.013. Worst case the abv will be higher but at what is the rule of thumb when initiating the rest to reach desired final gravity?

as Minbari said Diacytle rest is to raise a lager fermentation up to help clean up off flavours.
Yes I also use this final temperature rise as tool to help drive the fermentation to a finish.

When fermenting I watch fermentation either I'm watching how much my glycol is turning on and off or the co2 overflow slowing down then I'll let the fermentation thermal activity free rise to achieve FG.

Usually 19-20c

 

[dmtaylor]

IF I detect diacetyl in aroma or in a flavor sample, THEN I try to initiate the diacetyl rest when gravity points are half of original. For example, for OG 1.056, I would initiate diacetyl rest when gravity reaches 56/2 = 28 or 1.028.

IF I do NOT detect diacetyl, then I feel the diacetyl rest is an optional step that may or may not be beneficial.

As the others stated, the goal of the diacetyl rest has nothing to do with attenuation or the FG.

 

[Megary]

+1 to all of the above.

And as far as the recipe creator is concerned, the FG predicted is just an educated guess based on the average attenuation for each yeast. It’s not specifically the FG you will hit or even should hit. Consider it Brewer’s Friend’s equivalent to Fanduel’s “over/under” line.

 

[Zefram]

I don't normally mess with a diacetyl rest with ales unless fermenting at the lower end of the temperature spectrum with lighter beers, which seems to be your case. As a precaution, I'll raise the temperature to about 68°F when about 5 points from the expected FG and hold for a couple of days or so. It might lower the FG slightly, but hitting the expected FG is kind of a crapshoot for me anyway.

In short, stick to your plan and don't worry about the FG

 

[Steve Ruch]

IF I do NOT detect diacetyl, then I feel the diacetyl rest is an optional step that may or may not be beneficial.

I've never needed to do one in over 22 years of brewing.

 

[Simonpyman]

Thanks everyone, i should have stated that i know what the rest is for and that what i meant was that by increasing temperature you are likely going to reach a gravity past your expected FG.

i have been doing the rest blindly with all my lagers without sampling so i will follow the advice of testing at half the original gravity and proceeding to rest if i detect the buttered popcorn aroma/flavor.