How to Use a Chemex: Ratio, Grind Size & Step-by-Step

Action: Gently pour 2.5× to 3× the coffee weight in hot water (94°C) across the entire dry bed. Ensure all grounds are saturated.

Action: Pour steadily in gentle concentric circles from the center outward, stopping about 1 cm short of the paper edge, bringing total water to ~60%.

Action: Wait for the water level to drop halfway, then pour the remaining water steadily in slow circles until reaching 100% target weight.

Action: Allow gravity percolation to draw the water through the flat coffee bed. When flow slows to a sparse drip, lift and discard the filter.

Q1:What is the golden coffee-to-water ratio for a Chemex?

The specialty coffee gold standard for Chemex is 1:16 (1 gram of coffee for every 16 grams of water). For example, a classic 2-mug brew uses 30g of coffee to 480g of water. If you prefer a bolder, richer cup with more body, use 1:15 (30g coffee to 450g water). For delicate, high-altitude floral coffees (like washed Ethiopian or Geisha), use 1:17 (30g coffee to 510g water) to highlight subtle aromatic acidity.

Q2:What exact grind size should I use for Chemex brewing?

Chemex requires a medium-coarse grind, measuring between 800 and 1050 microns (resembling coarse kosher salt or rough sea salt). Because Chemex bonded filters are 20% to 30% thicker than standard pour-over filters, using a finer V60-style grind (500–700 µm) will clog the dense paper fibers, causing the drawdown to stall past 6 minutes and resulting in a bitter, over-extracted cup.

Q3:Which side of the Chemex filter must face the spout and why?

The side of the filter with three layers (3-ply) MUST face the pouring spout. The Chemex spout is not merely for pouring coffee; it is a critical air exhaust vent. If the single-layer side is placed against the spout, the wet paper collapses under suction, creating an airtight vacuum lock that halts liquid drainage completely. The stiff 3-layer fold bridges across the channel, keeping the air vent open.

Q4:Why is my Chemex draining so slow or stalling completely?

A stalled Chemex drawdown is almost always caused by one of three issues: 1) Airlock suction—the filter has collapsed into the pouring spout, sealing the air vent (fix by lifting the filter slightly with a wooden chopstick or spoon handle); 2) Grind too fine—excess micro-fines are choking the thick paper pores (coarsen your grinder setting); or 3) Excessive agitation—stirring the slurry too aggressively causes fine particles to migrate to the bottom of the cone.

Q5:Why does Chemex coffee taste cleaner and sweeter than French Press or drip?

The secret lies in the proprietary bonded filter paper. At approximately 210 microns thick, it is woven with a dense capillary pore structure that captures almost 100% of coffee diterpenes (cafestol and kahweol oils) and insoluble micro-fines. Without suspended oils coating your taste buds, you experience pure, transparent sweetness and delicate organic acids with zero sediment.

Q6:Do I really need to rinse the thick Chemex paper filter before brewing?

Yes, pre-rinsing is mandatory. Because Chemex filters are made of heavy laboratory-grade cellulose, brewing through a dry filter imparts a strong papery, cardboard taste to your coffee. Pour approximately 200 ml of hot water through the filter to wash away wood pulp residues and thoroughly preheat the thick borosilicate glass carafe. Pour out the rinse water through the spout while holding the filter in place.

Q7:What is the glass button or bead on the front of the Chemex?

The embossed glass bead on the lower bowl of the Chemex (often called the 'belly button') is an exact volumetric marker indicating the 50% capacity level of that specific brewer. For example, on a 6-cup Chemex (30 oz total capacity), the liquid reaches the glass bead when exactly 15 oz (approx 450 ml / 3 cups) has been brewed into the carafe.

Q8:What is the difference between white (bleached) and natural (unbleached) Chemex filters?

White Chemex filters undergo an oxygen-cleansing bath (chlorine-free bleaching) that removes wood lignin, leaving them neutral in flavor with minimal rinse required. Brown (natural) filters are made of raw, unbleached wood pulp and contain natural wood resins that require 2 to 3 times more hot rinse water to avoid a woody, cardboard taste. Professional baristas almost universally prefer white bleached filters for sensory transparency.

Q9:How do you brew Iced Chemex (Japanese Flash Brew)?

To make authentic flash-chilled iced coffee, use a 1:16 ratio but split the water weight: put 40% of the total water weight as clean ice cubes directly into the Chemex glass carafe (e.g. 190g ice for a 30g coffee dose) and brew with the remaining 60% as hot water (290g hot water at 95°C). The hot coffee extracts rich solubles and immediately flash-chills over the ice, locking in volatile floral and fruity aromas that are lost in traditional cold brew.

Q10:Can you place a Chemex directly on an electric or gas stove?

Classic Chemex carafes are crafted from non-porous borosilicate glass (similar to Pyrex laboratory glassware), which is heat-resistant. You can place it on a gas flame or glass-ceramic electric burner on LOW heat, provided there is liquid inside. For exposed coil electric stoves, you must use a stainless steel wire grid (the Chemex Wire Grid accessory) to prevent direct contact with the heating element, which can shatter the glass.

Q11:How do you clean and remove stubborn coffee oils from a Chemex?

For daily cleaning, remove the wooden collar and rawhide tie, then wash the glass carafe with warm soapy water using a soft bottle brush. For stubborn brown coffee oil stains or hard water mineral scale, fill the carafe with warm water and 1 tablespoon of sodium percarbonate (like Cafiza or OxyClean Free) or a 50/50 mix of white vinegar and water. Let it soak for 30 minutes; the glass will restore to sparkling laboratory clarity.

Q12:Chemex vs. Hario V60: What are the main flavor differences?

While both are conical pour-over brewers, the Chemex produces a noticeably lighter, cleaner, and more tea-like cup with higher clarity and lower perceived bitterness due to its 30% thicker filter trapping all oils. The Hario V60 uses thinner paper and internal spiral ribs that promote faster flow, yielding a brighter, more acidic, medium-bodied cup with slightly more mouthfeel and texture.