What is a Chemex?

The Chemex is an hourglass-shaped borosilicate glass coffeemaker invented in 1941 by German-born chemist Peter Schlumbohm in the United States. It uses a proprietary paper filter 20 to 30 % thicker than a standard filter, producing an exceptionally clean filter cup — oils, fines and sediment removed — with a delicate body and an aromatic clarity.

The Chemex was designed by Peter Schlumbohm, a German chemistry Ph.D. who emigrated to New York and filed the patent in 1941. Its hourglass silhouette with a wooden collar cinched by a leather lace has become an icon of industrial design: the vessel is in the permanent collections of the Museum of Modern Art in New York, the Philadelphia Museum of Art and the Smithsonian, and appears on the Illinois Institute of Technology's list of the 100 best-designed products of modern times.

The technical signature is the proprietary paper filter, 20 to 30 % thicker than a V60 or Kalita standard. That thickness traps more oils (the diterpenes cafestol and kahweol), fines and sediment, producing a very clean, almost tea-like cup. The filter comes in two shapes: pre-folded square, or circular. Correct folding — three layers against the spout, one on the opposite side — is key: it leaves an air channel between filter and wall for free drainage.

The Chemex is more forgiving than a V60 thanks to its restrictive filter: the slower flow produces a more even extraction even with a less precise grind, and the filter tends to buffer uneven pours. The trade-off is less expert control — you cannot dramatically reshape the cup just by modulating pour cadence. The reference recipe lands around 1:15 to 1:17, with a medium-coarse grind (coarser than V60, finer than French press) and a total brew time of 4 to 5 minutes.

It is sold in three sizes: 3-cup (15 oz), 6-cup (30 oz), 8-cup (40 oz) — plus a 10-cup. The 6-cup is the most common home size. Mind the variants: the Classic (without spout) requires removing the filter to pour, while the Handblown (with spout) lets you serve straight from the carafe. In Belgium, the Chemex is less common than the V60 in cafés, but popular in home brewing: its aesthetic is a recognised brunch centrepiece in open-plan Brabant kitchens.

Chemex — sizes and filters

Science and Design in One Glass Object

The Chemex is the rare coffee device that holds a permanent place in the collection of the Museum of Modern Art in New York, and for good reason: Peter Schlumbohm's 1941 design is a genuinely elegant engineering solution that integrates functionality and aesthetics without compromise in either direction. The hourglass shape of the borosilicate glass vessel is not decorative — the narrowed waist creates a natural air gap that allows CO2 and steam to escape during brewing without creating vacuum resistance that would slow the drain rate. The wooden collar and leather tie that have been a design constant since 1941 are practical: they provide an insulated grip point on an otherwise all-glass vessel that would otherwise be impossible to handle safely when filled with near-boiling liquid.

What most users do not realise is that the Chemex's proprietary filter is as much a part of the design as the vessel itself. Schlumbohm developed the thick, bonded filter specifically to produce the exceptional clarity of the Chemex cup — a filtration standard that standard pour-over papers do not match. This filter removes virtually all coffee oils and fine particles, producing a cup that is often described as crystal clear or glass-like in its transparency. The consequence is that the Chemex is maximally unforgiving of poor-quality green coffee or imprecise roasting: every flavour in the cup is presented without the oil-assisted buffer that gives body and texture to French press or metal-filtered coffee. A Chemex brewed from a defective green coffee will taste worse than the same coffee in a French press, and better from exceptional green coffee.

Practical Recommendations

When purchasing a Chemex, choose the size that matches your typical brewing volume: the 3-cup model (400ml) for a single large cup or two small ones, the 6-cup (750ml) for two to three servings, and the 8-cup (1.2 litres) for larger groups. The glass-handled models are easier to pour from than the classic wooden collar version but are harder to clean; both produce identical cup quality. Chemex paper filters are sold separately and are not interchangeable with standard pour-over papers — the size and bonding are different. Pre-fold and pre-rinse the filter before every brew: the thickness of the Chemex paper means rinsing is particularly important for removing paper-derived off-notes. Store the brewed coffee in the carafe for up to 45 minutes at room temperature — the glass retains heat reasonably well and the Chemex doubles as an attractive serving carafe without any additional vessel needed.