Don't bother with this. The seal created by the plunger is good enough to stop the flow of coffee. Insert the plunger at an angle so that you push out as much air as possible before straightening it out.
I’ve never understood the resistance to inverted brewing - with 200g of water, it’s trivial to make it work with minimal-to-no risk of an accident upon inversion.
Wait, what? The standard method is to put coffee into the Areopress right way up.
Having tried upside down and right side up immersion, I can’t say it makes much difference either way. In which case, I’d rather not have a top heavy vessel of hot water on the counter.
It also has the advantage of being able to inspect how the filter is seated before you proceed. I’ve had instances where the filter is not seated properly and excessive agitation manages to unseat the filter. If you reuse filters (and I taste no reason not to), I observe that the filters bunch up a little bit more with reuse.
Anyway, I don’t mean to say that you can’t invert things. But taste-wise, inverted brewing may have no clear advantages if you just want a nice coffee.
>5. Press gently
Does not compute?
A full grown adult standing with their full weight on their Aeropress can achieve about 4 bar of pressure; standing at the counter, pressing with one arm as hard as I can, I'm unlikely to achieve more than 1 bar. For context, an espresso traditionally requires 9 bar to properly extract. It's doubtful that that even 1 bar of pressure makes any difference to extraction at all.
But assuming that it does, and you think that pressure is a good thing - why on Earth would you instruct people to press "gently"? Now you're looking at more like 0.1 bar of pressure. That's definitely negligible, certainly not "high pressure" or even "relatively high".
I said the aeropress combined immersion and high pressure. What is 'high' is obviously relative, as I just qualified.
I did not say the higher the pressure the better, which is obvious enough from the fact I prefer using an aeropress to an espresso machine.
Aeropress FAQ:
"The AeroPress filter is 2.5 inches in diameter so the area of the filter is 4.9 square inches. If you press down firmly on a scale, it is relatively easy to get the scale up to 25 pounds and then if you press hard on the scale, you can certainly get it up to 50 pounds. Therefore if you press similarly hard on your AeroPress while brewing coffee, the firm pressing will be at 5.1 psi (25 lbs/4.9 sq in) and the harder pressing will be at 10.2 psi (50 lbs/4.9 sq in). Since a bar of pressure is 14.7 psi, the former is .35 bar and the latter is .70 bar."
https://www.aeropress.co.uk/pages/faqs
See also James Hoffman's experiment:
Aeropress allows you to combine immersion and high pressure with a £25 device that largely self-cleans, and is small enough to travel with. It makes a smooth, rich-tasting coffee.
With electric grinders you pay for the burr, which is what really matters, and then an electric motor. But if you buy a fairly decent hand grinder like the C2 chestnut, you get a far better burr for the same price, and because of that hand grinding is really easy-going and quick. I enjoy doing it every morning.
There are some coffee enthusiasts that create over-complicated aeropress recipes, but the truth is that it was designed for simplicity. What I've found matters is:
1. Small-to-medium grind size
2. Stand upside down to immerse for longer
3. Use 80-85c water
4. Stir
5. Press gently
Obviously the quality and freshness of the coffee beans matters too, and you can vary the immersion time for the strength of the coffee you want.