BLOG // // 16.10.2020

Chemex - What is It and How to Use It?

Chemex is an elegant looking coffee brewing device. Chemex can be used in cafes, at home or where ever you want to brew several cups at a time and have the audience fascinated by the view. Let's see what is Chemex about and how to brew coffee with Chemex!

What is a Chemex? 

It was back in 1941 when a German chemist, Peter J. Schlumbohm, invented this brewing device. 

He combined a laboratory glass funnel and an Erlenmeyer flask still widely used in laboratories. 

In this combination, an air funnel was needed to make a space for the air escaping when water was poured in. This funnel is up in the front of the device. 

Also, to save hands from the heat, he added a wooden belt to the waist of Chemex.

barista brewing with Chemex coffeemaker

Did you know that Chemex is a part of many museum collections in such famous places as Museum of Modern Art in New York?!

Method when brewing coffee with a Chemex

This is one of the devices that use brewing method called ”infusion”, sometimes also called ”drip” or ”gravity brew”. 

Infusion is the method where water is running through the coffee bed in a filter and down into a vessel below. 

Other methods of brewing are immersion (for example in French Press) and pressure (for example espresso) and the combination of these two (for example Aeropress). 

How to brew coffee with a Chemex? 

A barista should remember the fundamentals of brewing coffee, what ever the method and the device is. Follow the list below and check also our TOP 5 tips for great coffee.   

1.    Grind size and brew time: 

These two walk hand in hand. Coarser the grind, faster the water flow. Aim to at least a couple of minutes when using a Chemex - depending on the dose. Use quite coarse grind. Not too coarse as the water will pass the coffee bed too quickly and you will end up with under-extracted coffee. On the other hand, too fine grind size can block the brew completely and nothing comes out from the filter. The key is finer the grind, more extraction and more flavour.

Chemex coffeemaker

2.    Filter: 

There are a couple of types of filters you can use for a Chemex. 

First, the bleached and unbleached paper filters. We recommend the bleached ones, read here why! Papers are available in square form, half-moon shaped as well as round ones and they all are pre-folded. Half-moon shaped are available also unfolded. 

No matter which of the paper filters you choose, it is important to place it correctly into the Chemex. 

Here is how the manufacturer guides you to do it: 

  • Place your finger between the 3rd and 4th layer and open into a funnel. 
  • Place the funnel in the top portion of the Chemex coffeemaker, with 3 layers on the groove side

The groove is an air vent (as well as the pouring spout) and allows air to escape from the lower portion of the coffeemaker, letting the coffee filter at the proper rate. Placing the filter as directed prevents vent clogging and facilitates filtration.

Here is a great guide from the Chemex Coffeemaker on how to fold and place the filter paper.

If you prefer cloth over paper, there are also Chemex coffee socks available. In addition, there are also metal filters, but usage of them takes the personality of Chemex brew a bit away - at least in my opinion! If you want to know more about the differences between filter medias, check my blog on their characteristics. 

Remember to always rinse the filter prior to adding the coffee grounds in. Usage of hot water also heats up the device.

chemex rinsing filter paper
Rinsing the filter paper removes any papery flavours from your coffee!

3.    Dosing: 

The Chemex brews are pretty light bodied coffee. Keep that in mind when creating your recipe - you might want to use a little higher coffee to water ratio than for some other pour over brews. 

chemex dosing

4.    Water temperature: 

Go ahead and experiment between the SCA standard of +90-96 Celsius. Higher temperature, more extraction, more flavour! 

5.    Pouring and agitation: 

First you need to bloom the coffee in order to get rid of the excess CO2 and to make the coffee bed wet thoroughly. This is important to avoid channeling. Check out what Jori has written about blooming and dripping!  

Pulsing your pour gives the coffee grounds the opportunity to take time for extraction as they are not immediately fully saturated with just one pour.

Chemex pouring

By creating turbulence to the coffee bed during and after pouring you will not only increase the extraction but also make it more even. Agitation can be done by using a spoon or by spinning the device.

Read more about agitation and how it effects your coffee here!

6.    Serving and aftermath 

Toss the filter, swirl the batch and serve! You might want to place a lid or cup on top of your Chemex after the first serve to keep the coffee warm longer and prevent the aromas escaping.

Chemex serving

The outcome will be a remarkably clean brew. Chemex paper filters are 20-30% heavier than other filters. Due to this they retain more of the suspended oils during the brewing process. Also, many of the coffee solids cannot pass through the filter.

Remember to keep your Chemex clean! Remove the wooden handle and continue to hand wash with warm soap and water.