How long for a D-rest?

[fozzybeer]

Hi there. I'm brewing my first pilsner and have had it fermenting at about 8c for 4 weeks. It's dropped to about 1.014 from about 1.050. I'm planning on doing a diacetyl rest for a couple of days at about 18c (although it tastes quite good so may not need one).
My question is how long should I perform the rest before racking to secondary and lagering?
Should fermentation be complete before lagering or will it continue to ferment at lagering temp (was planning on about 4c)?

 

[SwampWater]

I do my d-rests for about 2-4 days depending on the ambient temps.

 

[fozzybeer]

And do you wait for fermentation to stop during the rest?

 

[Hogarthe]

yes, you need to have the fermentation done with before dropping to lager temps. I think if you drop the temp slowly, 1 or 2 degrees a day you can ferment at lager temps, but most people chill too fast and the yeast won't be doing anything once it's cold. so it is easier just to finish fermenting then drop to lager temp.

 

[fozzybeer]

Cheers guys.
I've rested it for about 4 days now and it looks like its pretty much done fermenting but there is still a bit of a butterscotch taste to it. Will this diminush in the lagering stage or should I continue to rest for a few more days at about 18C?

 

[Tore]

No use resting anymore now IMO. The yeast starts eating diacetyl before FG is reached, doing a diacetyl rest for longer than 2 days is useless if i have understood the literature correctly.

 

[Hogarthe]

if it still tastes butterscotchy I'd leave it in d rest. maybe even warm it a degree or 2.

 

[Ozarks Mountain Brewery]

the issues with the changes in temperature are purely for the individuals set up, the lagering is done in my opinion around 50ish and the drest is slowly raised up to 68 or so just to let all the yeast get out its junk so to speak, but the d-rest is also to get the remaining yeast that wasn't eating to eat so the time needed is purely for each yeast strain, not all are the same

 

[fozzybeer]

Thanks guys,
So I decided to rack to secondary and pop it back in the fridge at about 48F (My only temperature control is a fridge that I can regulate between about 48F and 38F, I could not increase the D-Rest temp)
Funny thing is it seems to be more active in the fridge than it was during the D-Rest!
So I think I'll just leave it for 3 or 4 weeks, but will do another gravity test in a week or so.
Is it possible there is still fermentation going on or at least junk clean up? Reading was 1.010 when I put it back in the fridge.
If I leave it at 48F will the yeast continue to do whatever clean up is required?
I could then drop the temp a bit after a couple of weeks...?

 

[Hogarthe]

the renewed activity could be gas that was trapped in suspension being released after transfer. lager yeast will still be working at 48 F, so it could be still fermenting, but 1.010 sounds like it should be done or very close to it. you can leave it for a few days to make sure. If 38 and 48 are your only temp options, I'd lager it at 38.