Why the Chemex Still Matters
The Chemex is one of the most recognizable brewers in specialty coffee, and for good reason. Designed in 1941 by chemist Peter Schlumbohm, its hourglass silhouette was inducted into the permanent collection of the Museum of Modern Art, but its real legacy lives in the cup. Where a Hario V60 or Origami chases clarity through geometry and flow, the Chemex achieves it through mass and material. The thick bonded paper filter is the centerpiece of the method, and understanding how it behaves is the shortcut to consistently clean, nuanced brews.
This post walks through the Chemex classic method: the filter, the ratio, the pour structure, and the small adjustments that separate a muddy Chemex from a bright, layered one.
A common rule of thumb among Chemex brewers: if the cup tastes dull, the filter is rarely the villain. The grind, water temperature, or pour rate usually is.
The Thick Bonded Filter: Not Just Paper
Chemex filters are roughly 20 to 30 percent thicker than a standard V60 or Kalita Wave filter, according to Chemex's own product descriptions. That thickness changes the brew mechanically in three ways:
- Slower flow rate. The bed spends more time submerged, which extends total contact time even at identical grind settings.
- Heavier oil and fine sediment retention. The cup ends up noticeably cleaner, with almost no body haze.
- Higher thermal loss. More paper absorbs more heat, which is why pre-rinsing matters more here than on thinner filters.
Bleached vs. Natural
Chemex sells both bleached (white) and natural (brown) filters. The domain consensus, echoed by baristas like Hoffmann, is that natural filters can leave a faint papery taste if under-rinsed, while bleached filters rinse cleaner and faster. For the classic method, bleached filters are the safer default.
Actionable tip #1: Rinse your Chemex filter with hot water until you have poured at least the full volume of your final brew through it. Discard that water before adding grounds. Under-rinsing is the single most common cause of a papery Chemex cup.
The Coffee-to-Water Ratio That Actually Works
Chemex itself suggests a ratio around 1:16 to 1:17, and that is a reasonable starting point. But ratios in isolation mislead. What matters is the interaction between dose, grind, and drawdown time.
For a standard 6-cup Chemex, a common approach looks like this:
- Dose: 40 to 45 g of coffee
- Water: 650 to 720 g, heated to around 94 to 96 C for most medium roasts
- Grind: medium-coarse, noticeably coarser than V60, closer to what you would use for a French press minus the mud
- Total brew time: in most cases between 4:00 and 5:00
If your drawdown is consistently over 5:30, the grind is likely too fine or the bed is clogging from excess fines. If it finishes under 3:30, grind finer or pour slower. Scott Rao has long advocated for using drawdown time as the primary diagnostic on flat and conical brewers alike, and the same logic applies to the Chemex despite its different geometry.
Ratio as a Lever, Not a Law
Think of the ratio as one slider among several:
- Lighter roasts often benefit from a slightly tighter ratio (1:15.5 to 1:16) and a finer grind to boost extraction.
- Darker roasts open up at 1:17 to 1:18 with a coarser grind, which prevents the cup from turning ashy.
- Aim for a target TDS range rather than a fixed ratio if you own a refractometer. For filter coffee, most roasters publish target TDS bands (often around 1.30 to 1.45 percent) and you can dial ratio to hit them.
The Classic Pour Structure
The Chemex rewards a calm, structured pour. Unlike **[Tetsu Kasuya](https://cup-timer.com/en/barista/tetsu-kasuya)**'s 4:6 method on V60, which leans heavily on pour-based flavor manipulation, the Chemex classic method is closer to a simple three-phase pour aimed at an even bed.
Phase 1: The Bloom
Pour two to three times the coffee weight in water (so 80 to 135 g for a 40 to 45 g dose) and let it sit for 30 to 45 seconds. The bloom releases trapped CO2 from fresh coffee. Skipping it, especially with beans roasted within the past two weeks, can lead to uneven extraction and sour notes.
Actionable tip #2: Give freshly roasted beans a longer bloom, up to 45 seconds, and gently swirl the Chemex instead of stirring. Swirling wets the bed evenly without disturbing the filter, which is what many April-inspired recipes also recommend for flat-bottom brewers like the Kalita Wave.
Phase 2: Main Pours
Pour in two to three slow, concentric spirals, each bringing the water level up to roughly the neck of the Chemex, then letting it drop about halfway before the next pour. Keep the pour stream gentle. Aggressive pouring agitates fines and slows drawdown in ways that are easy to overshoot.
Phase 3: Finish and Drawdown
Your final pour should bring total water to target. Avoid pouring on the filter walls near the end, since coffee stranded high on the paper will not extract and can dilute the cup as it slowly drips through. A flat bed at the end of drawdown is a good visual cue that the pour was even.
Troubleshooting the Classic Chemex
Use flavor as your first diagnostic, drawdown time as your second:
- Thin, tea-like, sour finish: likely under-extracted. Grind finer or extend contact time.
- Ashy, drying, bitter: over-extracted. Coarsen grind, lower temperature slightly, or shorten total time.
- Papery or cardboard taste: filter was under-rinsed, or filters are stored near strong odors. Rinse longer and store filters sealed.
- Muddy body, unusually long drawdown: too many fines. Check your burrs and try a fresh bag of filters.
Final Thoughts
The Chemex is sometimes dismissed as a slow or forgiving brewer, but in practice it is simply a different one. Its thick filter gives you an exceptionally clean cup that highlights acidity and aromatic clarity, which is why many roasters still showcase light-roast single origins on it. Nail the rinse, respect the ratio, and keep the pour calm, and the Chemex rewards you with one of the most elegant expressions of pour-over coffee you can make at home.