Skip to main content

The Chemex by James Hoffmann

I. History and Iconic Design​

  • Origin: The Chemex was invented by German-born inventor Dr. Peter Schlumbohm and patented in 1941, ultimately being released in 1942. It was his most successful invention, among over 300 patents.
  • Design: It is an incredibly simple and beautiful single piece of glass with a distinctive wooden collar and tie. Its design has made it an icon, frequently appearing in pop culture (e.g., Friends, Mad Men, Interstellar).

II. Unique Design Challenges and Solutions​

The Chemex's one-piece design (brewer and server combined) presents two key challenges related to its filter papers:

1. The Airlock Problem​

  • The Challenge: Since the brewing cone is fused to the base, an airlock can occur if air cannot freely escape as coffee flows into the lower chamber. This causes the coffee flow to stall.
  • The Solution (Spout): The Chemex features a specific pouring spout/channel that runs down into the base, which is designed to act as an air vent to allow air out during the brew.
  • Hack (Chopstick): If the paper forms a perfect seal over the glass, some people insert a chopstick into the brewer to ensure a constant air gap and prevent stalling.

2. The Filter Paper​

  • Unique Paper Design: Chemex papers are very large and are folded so that one side of the cone has a triple-ply thickness. This thick side must be placed over the air spout to prevent the paper from collapsing and sealing the vent.
  • Taste Impact: A single Chemex paper weighs about three times more than a standard Hario filter. This triple layer results in:
    • Cleaner Taste: The thick paper removes far more suspended material, resulting in an exceptionally clean cup.
    • More Resistance: The high resistance can lead brewers to grind coarser, potentially resulting in a weaker, under-extracted cup.
  • Rinsing is Critical: You must thoroughly rinse the thick paper to avoid a papery taste in your coffee.

III. Brewing Technique for Chemex​

Hoffmann emphasizes that brewers should not compensate for the paper's resistance by grinding much coarser, which often leads to under-extraction.

  • Ratio: 60 grams of coffee per liter of water is recommended.
  • Grind Setting: Use a grind setting similar to what you would use for a V60.
  • Brew Time: Expect a naturally longer brew time of 4 to 5 minutes when brewing a half-liter (500ml) of coffee, which is normal for the Chemex.

Pouring Method​

Use a technique similar to the V60:

  1. Bloom: Pour a 2:1 to 3:1 ratio of water to coffee (e.g., 60g–90g of water for 30g of coffee).
  2. Wait: Let the coffee bloom for at least 45 seconds.
  3. Pouring Phases: Follow a phased pouring approach (similar to V60) to gradually add the rest of the water.
  4. Finish: At the end of the pour, give the slurry a little stir and a swirl to flatten the coffee bed and ensure a fast, even drawdown.

IV. Design Preference​

  • The Classic (Wooden Collar): Hoffmann loves the aesthetic of the classic wooden collar and leather tie, but admits it's terrible for practical use, making cleaning or dishwashing difficult.
  • The Handle Version: The glass-handled version is more practical and easier to clean but, in his opinion, "just doesn't look as good" as the original.
  • Aesthetics: Ultimately, a unique appeal of the Chemex is how beautiful the final product looks—the glass base catches the light in a way that makes the coffee look more vibrant, red, and beautiful.