Looking online for a copy of our resources manual so I don't have to handtype section about press-brewing. Using too fine of a grind will result in bitter coffee and particulate matter.
I can't find it, but for any future coffee question, the defining online resource is Coffee Geek
from Coffee Geek
http://www.coffeegeek.com/guides/presspotFactors that make a good pot of Press Pot CoffeeIf there's one thing that you need to take away from this how to, it's this. Don't skimp on your grinder.
I get really irked at comments I see online, in alt.coffee, even in our consumer reviews section that say things like "it's good enough for a french press"... these are people talking about a blade grinder, or even the cheaper burr grinders like the Pavoni PA or the Braun KM30. I say to that: bull shite.
Let's think about something here. What is it about press pot coffee that makes people think the grind should be more forgiving? The bigger size of the grounds? The steep time? No, none of that. There's nothing in press pot coffee brewing that will allow for a crappy grinder to produce the same results that a good grinder can produce.
Grounds SizeEnlarge this picture (click it) and look at the bottom of the pot. All the particles are even - no dust. This is a near-perfect press pot grind.
With a press pot, particle size of the grounds is as important as it is for espresso. The difference is, you want uniform large particles, instead of uniform tiny particles. Cheap grinders can't give you either - they will give you a mixed bag of big and small chunks. Dust and boulders. It's what leads to the thing people dislike most about press pot coffee - the sludge.