Originally Posted by bo_
she, my apologies. i've had like 10 tabs open all day in various forums just reading, and was thinking the whole time that it was deathbrewers recipe for some reason.
i do understand that 75% = 3/4. i simply don't understand how to tell if it is 75% done. i have never lagered, this is our 5th batch overall.
Well, if you're expecting 1.016 for a FG, and it's at 1.020, and it started at 1.060 for example, it's a good time to raise the temperature for the diacetyl rest. You want to do it while the yeast is still active, but when the active fermentation is slowing.
I did NOT do the math on the above- I was using a guess as an example. You don't have to be exact, you just want to do it at the end of fermentation, but while the yeast is still active. If you miss it, and the beer is finished, it's fine to go ahead and do it then. It just works better if you "catch" the yeast still active.
After the diacetyl rest, I rack and then lower the temperature 5 degrees per day until I'm lagering at 34 degrees or so.