Chemex Coffee Brewing - History and Tutorial

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In December 2002, I went to the Vital Forms art exhibit at the San Diego Musuem of Art. The gallery focused on American Art during the Atomic age of 1940 through 1960. One of the pieces that caught my eye was a glass carafe used for brewing coffee. The coffee brewer was the Chemex. After leaving the exhibition, I went home and ordered a Chemex coffee brewer. I may not know "good art", but I do know good coffee. And I wanted to find out if the Chemex could make good coffee.

How The Taste Differs

The Chemex brews coffee using the infusion method, which makes it most similar to drip coffee in terms of body and taste. It's unbleached filters are a little thicker than those used by auto-drip filters. The result is a slower brew and a richer cup of coffee. Although not as rich as the french press, the Chemex does produce a sediment free cup of coffee that will impress anyone used to the weaker taste of most auto-drip coffee machines.

Although they use a very similiar brewing style, the Chemex and the auto-drip have some distinct differences. The first is the Chemex carafe is a heat-resistant glass beaker, not an electrical applicance. This means you will need a kettle to heat the water prior to using the Chemex. One of the complaints with many auto-drip machines is a brewing temperature that is too low. Although it is more work to heat up water in a kettle and then gradually transfer it to the Chemex, having complete control over the brewing temperature can yield a superior cup of coffee. And because it isn't an electrical appliance, the Chemex doesn't keep the coffee warm. It is your responsibility to keep Chemex coffee warm should you brew a full pot. The upside of not being an electrical appliance is you can take it camping. Just be sure to bring a kettle or pot to boil water over the campfire.

Chemex 10 Cup Coffee Maker
Chemex 10 Cup Coffee Maker

Chemex coffee also takes a little longer to make. The filters used are thicker than standard drip coffee filters. This translates into a longer saturation period before passing through the filter. Those used to auto-drip coffee will be able to detect the richness difference immediately. The Drip Coffee Brewers page on the Sweet Maria's web site says this about the Chemex coffee filters:

They are 20-30% heavier than any other filter and are a special paper formulation to remove undesirable sediment but allow positive aromatic compounds to pass through. The fine paper grain holds back "mud," while permitting correct filtration speed: a Chemex brews at least 1-2 minutes slower than normal paper filters, more in line with the optimal time that hot water and grinds should contact each other: 4 minutes.

Chemex History

American chemist Peter Schlumbohm (1896-1962) invented the Chemex brewer. It was released by the Chemex Corporation in 1942. This was during a time when 64% of all household coffee was made using a percolator.(Uncommon Grounds , Mark Pendergrast page 272) Mark Pendergrast in the book Uncommon Grounds writes about the popularity of the Chemex saying, It never challenged the percolator, except amoung highbrows and purists. Today the Chemex brewer and it's accessories are manufactered by International Housewares of Pittsfield, MA.

Grinding and Dosage

For dosage Chemex advises 1 rounded tablespoon of regular-grind coffee per 5-oz cup. Like any other brewing method, your best coffee will come after you make your own adjustments to the dosage. By "regular" grind, they mean coffee ground for an auto-drip. If the coffee is too weak either increase the dosage or grind a little finer. If the coffee gets "clogged" then use a coarser grind.

Step-by-Step Brewing

  1. Start heating some water.
  2. Using a drip-grind, grind up the amount of coffee you wish to brew. Note: The Chemex is available in 8,10, and 13 cup models.
  3. Setup the square filter inside the Chemex. Note: There are other filters which can be substituted, they should be easy enough to figure out. The following instructions are for the standard square filters. You'll notice the filter is a square folded twice. When you look down at it you will see 4 pieces or paper or 3 sections. Bend 3 of the pieces to one side. Once you separate the filter it forms a cone. This is where the grounds will go. I've read that you should rest the side of the filter with 3 sections toward the lip of the beaker for better saturation, but my experience tells me this isn't important.
  4. The square Chemex filter

  5. Place the ground coffee inside the filter.
  6. Coffee grounds inside filter

  7. Once the water boils, remove it from it's heat source. It's always good to wait a few seconds before pouring to bring the temperature down from 212° F to the 200-205° F range.
  8. The initial pour is very important. Instead of pouring all the water onto the grounds as you would with a press pot, you should only pour enough water to saturate the beans. Chemex states that wetting the grounds allows them to "bloom". After you wet the grounds wait 20-40 seconds. During this time trapped carbon dioxide (CO2) escapes from the grounds. The result is the grounds become heavier and they cling to the bottom of the filter. Some theorize that because most auto-drip machines don't do this step, the grounds inside those filters float and thereby do not get maximum flavor extraction.
  9. Chemex Initial pre-wet

  10. 20-40 seconds after the wetting, gradually start pouring more water. Don't fill it to the very top. Always allow at least an inch of room at the top. Stop pouring the water when you've reached your desired amount of coffee.
  11. Chemex brewing in action

  12. Once the water has passed through the filter, remove the filter and pour!

Post Brew

Like a press pot and most vac pots, it is your responsibility to keep any extra coffee warm. Besides chugging the remaining coffee quickly, two ideas come to mind. The first is transferring any extra coffee to a thermal carafe. Many people already do this with their auto-drip to prevent the coffee from cooking on the burner. The second idea is to place the Chemex on the burner where you heated your kettle water. If you used an electric kettle, then of course this idea won't work. The burner will be cooled from the initial water boil, but it will still be somewhat warmer than the counter-top. An electrical burner will be much hotter than the grate of a gas stove, so Chemex sells a wire grid that fits on top of the electric burner to prevent your glass brewer from cracking. If you decide to go this route, be sure to find a cover for the top to prevent heat loss in that direction.

Troubleshooting

ProblemSolution
Coffee Tastes Weak If the water passed through the filter as fast as a typical drip brewer then your grind is probably too coarse. Otherwise your dosage could be too low. A combination of using a finer grind and more coffee should produce a more robust cup of coffee.
Coffee Taste Too Strong Reduce your dosage and try again.
Coffee Gets Clogged Although a small amount of water at the end of a brew cycle may not pass through the filter, the majority should. Consider a slightly coarser grind.
Pre-Wet Taking Too Long Are you a home roaster? Super fresh coffee will have more CO2 in it than something roasted at the store a few days ago. I've found that super fresh coffee takes longer to settle after the initial pour. As long as the majority of the grounds have settled this is not an issue. I've even experimented with have a 2nd round of pre-wetting with beans just out of the roaster with good results.
Water Takes Too Long to BoilAs I stated in the press pot article - I feel your pain. Buy an electric kettle. You will thank me.

Cleaning

In the book Uncommon Grounds, author Mark Pendergrast stated the Chemex was difficult to clean. I disagree. It's a piece of glass. Rinse it out with hot soapy water. If it needs something more then it is dish washer safe. Just be sure to remove the handle. Untie the leather knot and the handle will fall right off.

Remove handle before cleaning Chemex in dishwasher

Overview

So does the Chemex make good coffee? Yes, but like many brewing systems it takes a little patience to find your sweet spot. The first few pots I made I found the body too thin for my liking. After tweaking the dosage and grind, I was able to make coffee that approached the richness of the press pot. However, the Chemex brewer is not for everyone. If you aren't a hands on coffee person then you won't enjoy the Chemex. If you don't mind the hands on approach and want a superior drip brewing system, then you should consider the Chemex.

Scott Estes of Lexington, KY writes: I've been using Chemexs since the 70s. A couple of points: Given that one is boiling water anyway, I always boil a full kettle. The 'extra' hot water can be used to: 1. Heat the carafe--and the cups for the coffee, for that matter. 2. Clean the chemex. I only resort to soapy water occasionally, merely rinsing the coffee maker after I've transferred the brew to a thermos bottle.

UPDATE (October 2010): When this article was first written in 2003, I didn't add a step for rinsing the paper filter. Doing a rinse will reduce the paper residue taste in the coffee.

UPDATE (March 2013): If you don't want to mess with paper filters, there are now two metal filter options on the market. The links are below in the Resources section.

Resources

Chemex 10 Cup Coffee Maker - Amazon USA product page.

Chemex Pre Folded Circle Coffee Filter - Amazon USA product page.

Coava Kone Pourover Filter - Amazon USA product page.

ABLE KONE COFFEE FILTER 3RD GENERATION - Amazon USA product page.

Published: January 2003, Last Modified: March 2013, Author Google+