I've been lagering my Baltic Porter for about 2.5 months so far. I plan to bottle my 5 gal. batch in 12 oz. bottles in a day or two. How much sugar do I use? I know there are calculators on the web for calculating the amount of sugar to use depending on how high the fermentation temperature got, but do these also work for beers that have been lagered?
Should I let the beer warm to room temperature for a day or two before bottling, or just bottle it cold?
The beer temp parameter on those bottling calculators are trying to determine how much residual disolved CO2 is still present in the beer from the initial fermentation. As the yeast metabolize the sugars they produce co2 which disolves in the fermenting beer to an extent determined by the temperature of the beer (colder = more CO2 in solution, warmer = less) and the pressure the beer is under in the fermenter (just a tiny bit above ambient for most homebrewers). However once CO2 escapes solution it won't go back in unless pressure is increased. The yeast continue to produce more CO2 as the work so CO2 lost will to some extent be replaced. However once they have mostly gone dormant and ceased metabolizing sugars into CO2 and alchahol the amount of disolved CO2 will only decrease with decrease in temperature and/or pressure as no new CO2 is being produced. so what you want to determine is the highest temp the beer reached after the yeast were done producing CO2.
Whew... that was long winded. so If you crashed or stepped the temp down after the beer had acheived FG you would want to use the temp BEFORE you lowered it (around 40-50 I would guess).
And as Weithman5 says, you will need to warm the beer up to room temp or so to get the yeast back to work on the priming sugar.