I, like millions of coffee lovers the world over, love the Aeropress. It has virtually replaced the clunky ol' "French" Press. I use my old FP to make tea now. The Aeropress is similar to the FP in some ways but the fine filter allows a much finer grind and, hence, a shorter "extraction" time for the water to steep the grounds. The pressure exerted on the brew by the plunger also helps accommodate a finer grind. Supposedly this press makes "espresso", but it doesn't even come close. In all fairness, it does make an excellent "sweet" rich cup of coffee because the recommended extraction time is around 30 seconds using a relatively fine grind. The problem with the French Press is that it needs around 4 minutes extraction time to extract enough of the flavor compounds (essential oils), including the ones that make brewed coffee bitter. The Aeropress's relatively short extraction time mimics that of a proper espresso machine. It doesn't even try to mimic the pressure of such a machine but that's another story. The short time that the grounds spend in contact with the water makes for a "sweeter" coffee basically. The bitter oils are kept to a minimum. One problem IMO, and in that of a growing number of Aeropress users, is that this also makes for a weaker brew. So I, like apparently many other people, simply increase the time to like a minute or so. To add to the short time problem, which results in a weaker brew, the filter is porous enough that it lets flow a considerable amount of "under-extracted" coffee into the cup so that, when the steep time is up, about half the coffee or more in the cup has spent less than the allotted time on the grounds.
To compensate for the above-mentioned problems, some people have taken to inverting the Aeropress's cylinder, with the cap removed and the plunger in place at the "bottom", and then letting the brew sit for a minute or more before tilting it, still upside down, at about a 45 degree angle, and awkwardly trying to push the plunger from underneath. I have tried this and found the whole procedure messy and awkward. At the 45 degree angle, the "puck", formed by the grounds, remains mostly in the original position while the water doesn't. This makes for a somewhat uneven extraction. It is a bit of a pain to move the plunger in this awkward position and you have to hold the sides of the, now hot, cylinder to steady it. There are videos showing how to do this. Some really fanatic people get into precise temperatures and how many grams of coffee at a particular grind, and so on. Frankly, IMO, this kind of precision is only warranted if you have a multi-thousand dollar commercial Italian machine. But OK, the fussing about temperatures, and grind, and grams aside, there is some merit to increasing the time and eliminating or greatly reducing the flow of under-extracted coffee. I'll be honest, the difference in taste is not really overwhelming. It is slightly fuller, richer. You get a tiny bit of the oily crema into the cup, and it looks impressive, seeing that creamy foam flowing into the cup. And it still lacks the bitterness of the FP method. One thing I observe in the videos, and have experienced myself, as I mentioned, is just how awkward and cumbersome the inversion method is. I abandoned it early on and came up with a much simpler, less awkward way to achieve the same result. I will warn the fanatics ahead of time, so they don't start flooding this post with critical comments, that this simpler method does let through a, IMO, negligible amount (we're talking milliliters) of under-extracted coffee. That, mixed with the 250 ml or so of properly extracted coffee, is undetectable, I suspect, by even the most discerning palates. That's the only difference really, but you've been warned.
This method uses the Aeropress as it was intended--right-side-up. The only thing I do differently is, after stirring the coffee/water mixture with the included paddle, I immediately cap off the cylinder with the plunger, drawing it upwards just a slight amount in order to create a slight vacuum. That's it. The vacuum radically reduces the flow, even stops it if you are careful. This step has to be done carefully. I have had the experience of the filter paper edges being sucked up into the chamber and dumping tons of grounds into the cup. Not a pretty sight. So do be careful when you try this. You will develop a feel for just how much to pull the plunger. Notice that I tweak it in several steps to prevent a disaster. I would recommend doing it the same way. Again, the amount that does leak through is truly negligible so most of the coffee has spent however much time you wanted in the cylinder before being expressed into the cup. I now set a one minute timer while I go and clean up the stirrer. The time in the video is a full two minutes but that's probably too much. You'll notice in the video that the final pressing of the finished coffee is quite slow. That is because I choose to grind the beans almost as fine as an espresso grind for a rich robust coffee.
This is a short but sweet Instructable. All you need to know is in the video so enjoy.