To start, making coffee weigh out a portion of beans for the grinder. Generally, about 18g per person should do it. Chemex coffee is enjoyed with a brew ration of 1:14 to 1:16. That means for 18g of coffee you should be adding around 250g of water.
What grind should I use?
Chemex uses a coarser grind setting when compared to aeropress or straight espresso. It takes a little longer to make. The time that the water and the coffee is brewing for is called “contact time”. The total contact time that the water should make with the coffee is between 3 and 5 minutes. Use shorter time for a more acidic taste and longer for a deeper more bitter taste.
A Chemex uses a paper filter like an espresso machine uses a perforated basket or a French press uses a fine mesh. The coffee filters come pre-folded in some cases, otherwise follow the directions to fold them into shape.
As you add hot water to the coffee a few things should start to happen. The coffee should start foaming up as the beans release gases and the aroma inside. Some people prefer to pour a little hot water in, wait about 30 seconds for the bloom to foam up, then continue pouring. Others like to pour a bit more water in an give the beans a stir.
Good things come to those who wait
The coffee should take a good 3-5 minutes to pour through the grinds. If the pour is happening too quickly you can use more finely ground coffee. Similarly if it is taking too long, you can grind more coarsely.
Add the water slowly
Water should be added to the Chemex slowly, rather than all at once. Using a goose-necked kettle is a great way to do this, but if you don’t have one you can just pour the hot water in a small milk jug and do it that way.
Ready to Enjoy
Once the Chemex has finished brewing you can discard the paper and coffee grinds. They are biodegradable and make excellent compost material. Pour the coffee into a glass or mug and enjoy. Chemex tastes a little different than other kinds of coffee. It is a smooth, sweet taste that is reminiscent of tea. It makes a great beverage to share.