I have been brewing quite a bit with my french press recently. Weighing coffee, weighing water, etc. in an attempt to be as precise as possible. I've also been employing the James Hoffman "scoop before press" method (I think someone predated James in this, but I learned about it on jimseven.com--apologies to the originator). The resulting extractions have been really nice.
However, I have noticed that after about 10 minutes the extraction seems to go south. Nuances break down, and the flavor generally becomes unpleasant (scientifically speaking). I began pouring the coffee off into another container to ensure no passive extraction post plunge. With traditional drip brews, I am usually good for 35 minutes before I start noticing significant decline.
Has anyone else noticed this? Is it owing to fines working through the screen and continuing to extract? Any other theories?