Chemex

The Chemex was designed by chemist Peter Schlumbohm in 1941 and has barely changed since. Its hourglass shape, wooden collar, and leather tie are instantly recognisable — but the real story is in the filter. Chemex uses a proprietary bonded paper filter that is 20–30% thicker than standard filter papers. That filter is what defines the cup.

The Filter and What It Removes

Standard filter papers allow some fine particles and a small amount of oils through. The Chemex's thick bonded filter removes virtually all of them. The result is a cup with exceptional clarity — low sediment, minimal lipids, and a transparency of flavour that few methods can match. Individual aromatic compounds read with unusual precision because there's nothing in suspension muddying the picture.

The tradeoff is body. Chemex cups are notably light in texture — delicate rather than substantial. This makes it a polarising choice. Drinkers who prioritise mouthfeel and richness tend to reach for a French Press. Drinkers who want to taste exactly what a coffee is doing find the Chemex revelatory.

Ideal Parameters

• Temperature: 92–95°C. The thick filter retains heat slightly, so starting at the higher end compensates for minor temperature loss during a 4–5 minute brew.
• Ratio: 1:15 to 1:17. The Chemex's clean filtration means you often want slightly more coffee relative to a V60 to compensate for the reduced body. 1:15 gives a fuller cup; 1:17 is delicate and almost tea-like.
• Grind size: Medium-coarse. The thick filter creates more resistance to flow than a standard paper filter. A finer grind will cause the brew to stall or produce an unacceptably long drawdown. On a Comandante C40, 28–32 clicks is a useful starting range.
• Total brew time: 4:00–5:00 minutes. Longer than a V60 due to filter resistance.
• Dose: The 6-cup Chemex typically brews 40–50g of coffee to 600–800ml of water.

Brew Technique

Fold the Chemex filter so that three layers sit against the spout side — this prevents the filter from collapsing and blocking the spout vent. Rinse thoroughly with hot water to remove any papery taste and pre-heat the vessel. Discard the rinse water.

Bloom with 2–3x the coffee weight in water (80–120g for 40g of coffee) and allow 45 seconds. The bloom period is important in the Chemex because the thick filter means there's less opportunity for CO2 to escape mid-brew — a good bloom now means a less obstructed main pour.

Pour in slow, controlled concentric circles. Unlike the V60, the Chemex has enough volume that you can pour in 3–4 larger additions rather than continuous low-flow pours. Let the water level drop to just above the grounds between additions. Avoid pouring along the filter walls — this bypasses the coffee bed entirely.

What It Emphasises

The Chemex is at its best with washed, light-roasted coffees from high-altitude origins — Ethiopia, Kenya, Colombia, Guatemala. These coffees have complex acidity and aroma that the Chemex resolves into something unusually precise. A Yirgacheffe brewed in a Chemex will give you jasmine, bergamot, lemon in a way that feels almost like smelling the dry grounds, not a heavy liquid.

It is less suited to natural-process or darker-roasted coffees. The body those coffees bring to the cup is largely filtered away, leaving something thin and one-dimensional. A French Press or AeroPress will serve those coffees better.

Practical Notes

• The Chemex is made from borosilicate glass and can be placed directly on a gas flame or glass stovetop on low heat to keep coffee warm — one of its practical advantages.
• Filters are available in pre-folded squares or circles. The square filters fold to fit the cone; the circles are pre-folded for the Chemex-specific shape.
• Always use Chemex-branded or equivalent thick filters. Standard V60 or Melitta papers will under-filter and change the cup character significantly.