Can anyone give me the formula for bittering effect when adding hops after the boil? All the formulas seem to require OG, Alpha content & boil duration, but adding a mountain of hops after flame-out (during the swirl) would seem to me to be adding IBU's as well. At least that's what I suspect. But without good data and a formula, how do we measure this? In the absence of hard data I'm not persuaded that with a steep time of, say, 30 minutes (during cool down from 205 to 180F) we would not be adding significant IBUs. And if it does, we ought to be able to calculate this.