The Press Pot, or French Press, is one of the simplest forms of brewing coffee, and continues to enjoy a huge following. The irony is that many press pot devotees produce cup after cup of poorly executed coffee for a number of reasons. With a little knowledge and technique, the results can be improved.
Target Cup – The first point that needs to be understood is that the press pot is not the best brewing method for every roast and every coffee drinker. Press pots tend to excel with darker roasts that offer body and roast more than subtle coffee flavors. That does not mean that a delicate light to medium roasted coffee cannot be brewed well in a press pot, but darker roasts needs less finesse to achieve decent results.
Fresh Beans – Of course, freshly roasted, high quality beans are the most important key to success. A press pot cannot turn Yuban into a good cup of coffee without a significant level of divine intervention. As with other brewing methods, your beans should come from a local specialty roaster who can tell you when your coffee was roasted, or from your trusty home roasting stock. You can achieve good results from nitrogen flushed coffee that has been sitting on a supermarket or chain shop shelf, but you do give up many of the most delightful and transient flavors.
One of the advantages of the press pot is that it does allow you to brew coffee that is too fresh. Roasted coffee must be given time to off-gas for approximately three days, but if you have to shave a little time off of that wait period, the press pot behaves better than the pour over or AeroPress methods. Coffee that is still off-gassing will bloom so much that it can overflow a pour over filter, or at least make it very difficult to brew for less than 3 minutes. An AeroPress will overflow, or allow you to only add a fraction of the water you normally would. The press pot, on the other hand, has plenty of room for aggressively blooming coffee. The extra off-gassing during brewing will actually slow the brew, so 15-30 seconds should be added to the total brew time.
Water – The quality of your water is critical. In many parts of the world, tap water is a perfectly good choice, but if not, filtered water should be used. Water can be tested for total dissolved solids (TDS), and exact profiles of those solids can help understand how your coffee will interact with the water. If you are just shy of insanely obsessive about your brew, you can perform this simple test: Does the water taste good by itself at room temperature? If you have to chill or flavor your water to drink it, use a better source; your coffee will thank you.
Water Temperature – Once you have great, fresh coffee, and high quality water, water temperature has the next largest impact. There are plenty of studies showing that coffee hits its magic peak when brewed between 195-205 degrees Fahrenheit, give or take a few degrees. The same applies to press pots. The trouble is, however, that most press pots are glass cylinders with no insulation. By the end of the brew cycle, the pot has lost several degrees, and the extraction can be incomplete or even off target. To compensate for this, many make the mistake of using water that is at a rolling boil so that the resulting brew will be above 195 degrees Fahrenheit. The boiling water manages to extract some very unpleasant flavors which are often hidden under several tablespoons of sugar. The better option is to use an insulated press pot. There are also many aftermarket cozys for press pots, or you can simply wrap a few clean, dry dish towels around the press pot while brewing. That may not be as pretty as a bare press pot brewing away, but this is all about the coffee, and the results will be better.
Grind and Time – The grind size and brew time are directly related. The larger the grind size, the longer the brew time (at a steady temperature!). Press pots have fairly course screens, so the grind size should typically be the largest of any technique’s grind. Exactly how large is difficult to describe, but can be adjusted and nailed down with a few brews.
The most important part of the grind is consistency. Here, more than any other technique, blade grinders just will not do. Press Pots have the longest brew time of any hot brewed method, so while the larger chunks (boulders) may be under extracted, the smallest bits (fines) will be severely over extracted. The results can be a weak, yet bitter brew which is exactly the opposite of what we want. If a decent quality burr grinder is not an option, your local roaster will almost always grind your coffee when you purchase it, but you are giving up some freshness in exchange for grind consistency. Until a burr grinder is within your budget, this is probably an acceptable trade off.
Time is hotly debated, as is so common with coffee. The reality is that only you can determine how long to brew your coffee. I recommend three and a half minutes. Many sources suggest four minutes, but I find that my coffee tends to over-extract with that time, and I do not like to push the brew to the very edge. Start with three and a half minutes, and move that up or down by ten second intervals until you find your sweet spot.
Technique – Finally, technique can certainly impact the resulting brew, albeit less than the factors already reviewed. The biggest impact of technique, in my opinion, is to the ease of plunging and sediment layer at the bottom of your cup. I recommend that you:
Start with a clean, pre-warmed press pot. Before brewing, fill the pot with boiling water so the pot itself will steal as little heat from the brew water as possible. Dump the heating water and add the ground coffee and brew water until the pot is about three quarters full. Start your timer.
At this point, the coffee will bloom. There is no need to be delicate here, so using an appropriate spoon (metal tends to crack hot glass), give the mixture a good stir for 15-30 seconds. There are many who will scream “Blasphemy” at the idea of stirring, but I have yet to see the proof that stirring is not good for the brew. To the contrary, brewing ensures that all of the grinds are equally exposed to the brew water. This is especially important with fresh coffee, as the bloom can suspend coffee grinds in the foam, which is broken down by stirring.
After the stir, top-off the pot with brew water, place a saucer or other lid (not the press pot lid) on top of the pot, and ponder life’s mysteries for a few minutes. Again, we are shooting for about three and a half minutes, so we have about two minutes of down time.
Now, here comes the magic! One of the most common complaints about press pots is that it is hard to plunge, but fortunately there is a simple and effective solution. After the coffee has brewed by itself for the extra two minutes or so, a large portion of the coffee grinds will have floated to the top. Using two spoons, you can scoop most of the grinds out and into your composting container. Another advantage is that this reduces the volume in the pot, meaning there will be less chance of overflow when the coffee is plunged. This step does not need to collect all of the floating grinds, so just give it one sweep and move on.
Now, the plunger can be placed on the pot, and the plunger slowly pressed. Your coffee is done, but the remaining grinds continue to extract, so you must pour the brew into your cups or another container right away.
The second most common complaint about press pot coffee is the sludge at the bottom of the cup. The consistent grind size will do a lot to reduce fines, but some will remain. The best way to avoid sludge, barring a paper filter, is to let the press pot sit for a few seconds after plunging. Yes, a few seconds more of extraction will occur, but if we shoot for three and a half minutes instead of four, we can afford that time.
During those extra seconds, a lot of the fines will settle, just like they would in your cup. Now, slowly pour out the pressed coffee with the smoothest motion you can manage. This will help keep the fines at the bottom, and out of your cup. The last little bit of liquid in the pot should be sacrificed; they are mostly sludge anyhow.
If all of these steps have been followed properly, the coffee is still too hot to drink, unless you are adding milk, so let it sit another 30-60 seconds before taking your first sip. The fines will continue to settle in your cup, leaving you a reasonably clean, but very full bodied cup of joy.