Coffee Physics: When There’s Too Much Press in the French Press

When pressure comes up against an immovable force, something has to give. Barista and barista trainer, Erin Meister, met that immovable force while making coffee and recently shared her experience with readers. It’s all because of those fines, those dastardly bits of coffee grinds that are basically coffee dust, a result of the grinding process. As an example of how mishaps can happen to even the best of us, Erin was preparing to brew a French press coffee. As she pushed down the press, there was so much resistance, the plunger just wouldn’t plunge. Not listening to the little voice inside her, but hurrying a little too much, she pushed past the limits of the glass carafe, which shattered and left her with a room full of glass, coffee grounds and water.

Erin explains that in the grinding process, some of the coffee grounds are ground much finer than the bulk of the beans. Not surprisingly, these fine dust-like grounds are called “fines”. They are so small that they become stuck in the screen filter, making it hard for the water to pour through. This is what prevents the plunger from plunging. This is one of those times to remember what your dad always told you: “Do not force things.” Take a deep breath, step back, re-group and do this: Apply slight pressure to the plunger and then draw it back up about a quarter inch. This should dislodge the fines. Try plunging again and repeat the process if it still refuses to go down.

If you don’t like your pressed coffee to steep overlong in the pot, it might be a good idea to 1. Thoroughly clean your mesh filter, making sure to remove the fines as completely as possible, and 2. Draw back the plunger right after starting to push it down, just in case there are any fines to dislodge. That way there will be less chance of over-steeping the grounds. The French press is a simple and easy way to prepare great coffee. It just takes a little proactive understanding of coffee grind behavior to prevent such mishaps as Erin’s. Brew on - proactively!