I agree with your confusion, are we all talking about the same thing?

Plunging pushes your coffee through the metal filter. Pushing harder pushes the coffee through the filter with a higher pressure. Higher pressure pushes particles past the filter more easily than lower pressure. Coffee particulate has a tendency to make coffee more bitter.

Anything that gets more small particles past your filter will add to your coffee's bitterness. This can happen when using a ground coffee that has a lot of fine particles, or if you agitate when you pour/plunge.

I don’t know anyone who’s jumping up and down on the plunger or doing anything more than pressing it slowly. Have to imagine the coarseness/evenness of your grind is a 10x bigger factor in that regard

> or doing anything more than pressing it slowly

I have a french press for camping, it's fine but when I want that first cup of coffee and it's cold and rainy outside you better believe I'm not pressing it slowly.

Three seconds faster? You must really like coffee

Hm maybe not that fast, whats considered fast?

>I don’t know anyone who’s jumping up and down on the plunger or doing anything more than pressing it slowly.

Also my reaction the first time someone tried to tell me to plunge slower.

>Have to imagine the coarseness/evenness of your grind is a 10x bigger factor in that regard

100%. Plunge speed makes a minor difference at most, and only then when you have a suitably coarse and even grind.

If you want to play with the concept I think the best way is to prep a press, but instead of plunging the filter into the coffee before pouring, press it only to the top of the liquid and pour, allowing gravity to pull coffee through the filter. Pour a small cup like this, then press the rest of the way and pour another cup.

Given the grind has already been specified as an espresso-level of fineness (we're talking about a cold brew recipe), most of the grinds are going to be able to get through the metal filter.

The original suggestion of plunging slowly and gently is entirely sensible, since it's the only variable available in the context.

I used to plunge down hard and fast because I liked to see the bubbles.

But I realized less disturbing is better, and I started barely using the plunge - just to catch grounds when pouring.

After a while I went back to pour-over. The flavor is so much better - French press is now used for loose leaf tea and I have a lot more fun plunging.