The Chemex Legacy
The Chemex coffeemaker was designed and patented in 1941 by German-born chemist Dr. Peter Schlumbohm , a perfectionist inventor who held over 300 patents during his lifetime. As a scientist, Schlumbohm understood coffee extraction at a molecular level, identifying only two desirable components for the perfect cup: aromatic coffee oils and caffeine .
The Chemex received prestigious recognition when it appeared on the cover of the Museum of Modern Art’s “Useful Objects in Wartime” bulletin in 1942 . Today, the Chemex remains in MoMA’s permanent collection and was selected by the Illinois Institute of Technology as one of the 100 best designed products of modern times . Despite over 70 years of coffee innovation, the exact same design is still manufactured today, proving the staying power of great design .
Equipment and Materials
Brewing exceptional Chemex coffee requires specific equipment and proportions. Start with a 1:15 coffee-to-water ratio—for every 1 gram of coffee, use 15 grams of water, which converts to about 3 tablespoons of coffee per cup of water . Some prefer a slightly lighter 1:17 ratio—for every 1 gram of coffee, use 17 grams of water .
Grind your coffee to a medium-coarse consistency, similar to the texture of sea salt . Too fine a grind will clog the filter and cause over-extraction, while too coarse will lead to under-extraction and weak brew .
Essential equipment includes a Chemex brewer, specialized Chemex filters, a burr grinder, a gooseneck kettle for controlled pouring, and a digital scale for precise measurements. Use a digital scale accurate to 0.1g for both coffee and water—small variations of 1-2 grams can noticeably affect flavor .
Water Temperature and Preparation
Heat water to between 194-205°F, just below boiling . For most brewing, aim for 200-210°F—darker roasts perform best at the cooler end of this range, while lighter roasts benefit from hotter water . A practical approach is bringing water to a boil and letting it sit for one minute to reach approximately 200°F .
Unfold the Chemex filter so the three-layered side covers the pouring spout . Rinse the filter with hot water to remove any papery taste and preheat the brewer . Pour out the rinse water while keeping the filter in position .
The Brewing Process
Add your coffee grounds to the filter and gently shake until level, then zero your scale and start your timer . The brewing process involves multiple controlled pours for optimal extraction.
Begin with the “bloom” pour—starting from the center, pour in a spiral pattern at approximately 10g per second until you reach about 80g of water (or 3-4 times the weight of coffee) . Allow the coffee to bloom for 45 seconds . If using fresh coffee, you’ll notice the bed of grounds rise and bubble during blooming .
After blooming, continue pouring in slow, circular movements until water nears the top of the Chemex, then allow the water level to drop before adding remaining water . Many brewers use a pulsed approach: pour an additional 70g every 30 seconds until reaching total water weight, typically requiring 5 total pours over 2 minutes and 45 seconds .
Timing and Troubleshooting
Total brew time should be between 3.5-5.5 minutes, including the initial bloom . Denser coffees like Ethiopian varieties will take longer (closer to 5:30), while Central and South American coffees typically fall on the shorter end .
If brewing takes longer than 4-5 minutes, your grind is likely too fine—try coarsening it slightly . Weak coffee despite proper ratios typically indicates under-extraction: try a slightly finer grind, increase water temperature to 200-205°F, or adjust pouring technique for more even saturation .
Once brewing is complete, remove and discard the filter, then swirl the coffee gently before serving—this helps aerate the coffee and brings out its full flavor profile . Chemex filters are compostable and can be disposed of with the spent grounds .
The Science of Chemex Filtration
Chemex’s proprietary bonded filters are based on laboratory paper and are 20-30% thicker than standard coffee filters . These filters remove fats, bitterness, acidity, and sediments that other filter types leave behind, resulting in an incredibly flavorful and pure cup .
The filter thickness is crucial—it slows water movement through the grounds and removes a higher percentage of oils and insoluble components than standard filters . The filter’s formulation permits optimal infusion time by regulating filtration rate—neither too slow nor too fast .
The thick bonded construction eliminates oils and sediment that would otherwise create bitterness, resulting in a crisp, complex cup with remarkable clarity . This precise fractional extraction filters out undesirable bitter compounds while allowing only the desirable flavor elements to pass through, with the cone shape ensuring uniform extraction as water flows through all grounds toward the apex .