The Perfect Chemex: A Precision Brewing Guide
The Chemex produces a remarkably clean, tea-like cup with exceptional clarity. Its thick bonded filters and elegant design create a brewing experience that's both functional and beautiful. Here's how to consistently brew outstanding coffee.
What You'll Need
- Chemex brewer (6 or 8-cup)
- Chemex bonded filters
- 30g coffee beans
- 500g water at 94°C
- Burr grinder
- Scale with timer
- Gooseneck kettle
Grind Size: 900-1100 Microns
The Chemex's thick triple-bonded filter requires a coarser grind than most pour-overs—aim for 900-1100 microns. This coarser range compensates for the filter's resistance and slower flow rate, preventing over-extraction and stalling. Too fine (below 800 microns) causes extended brew times and bitter, papery flavors. Too coarse (above 1200 microns) produces weak, underdeveloped coffee.
Starting Point: Begin at 1000 microns for a clean, balanced cup.
Fine-Tuning: The Chemex benefits from thoughtful, incremental adjustments. If your brew time exceeds 5:00 or tastes bitter and astringent, move coarser by 40 microns (try 1040). If it finishes under 3:30 or tastes sour and thin, go finer by 40 microns (try 960). These measured steps help you navigate the narrow window between clarity and extraction.
Advanced Dialing: Once you're in the ballpark, 20-25 micron adjustments can refine your cup—balancing sweetness, enhancing body, or sharpening clarity. This precision is particularly valuable with the Chemex, where small grind changes significantly impact flow rate through the dense filter.
Bean Variables: Light roasts often need 950-1000 microns to achieve proper extraction without stalling. Medium roasts work beautifully at 1000-1050 microns, showcasing the Chemex's signature clarity. Dark roasts benefit from 1050-1100 microns to prevent bitterness. Document your exact settings—the Chemex is remarkably consistent when variables are controlled.
The Brewing Method
Prep: Unfold the Chemex filter with the three-layer side facing the spout. Rinse thoroughly with hot water—the thick filter requires more rinsing than standard filters. This eliminates paper taste and preheats the brewer. Discard rinse water, add your 30g of ground coffee, and gently shake to level the bed.
Bloom (0:00-0:45): Pour 60g of water in a gentle spiral, starting from the center and moving outward. Ensure all grounds are saturated. The thick filter slows water movement, so pour gently to avoid disturbing the bed. Wait until 0:45.
First Pour (0:45-1:30): Pour slowly in concentric circles to 250g total. The Chemex's wide opening allows for controlled pouring—maintain steady contact between water and grounds without creating turbulence. Keep the water level below the top of the filter.
Second Pour (1:30-2:30): Continue pouring to 400g total. Maintain the same gentle, circular motion. The thick filter creates natural resistance, so there's no need to pulse aggressively.
Final Pour (2:30-3:15): Pour to your final 500g. Allow complete drawdown.
Drawdown: Total brew time should be 4:00-4:45 minutes. The extended time is normal—the thick filter naturally slows extraction, producing the Chemex's characteristic clean profile.
Troubleshooting
Too bitter or astringent? Move up to 1040-1080 microns, or reduce water temperature to 92°C. Also ensure you're not over-agitating the bed during pouring.
Too sour or weak? Dial down to 950-980 microns, or increase water temperature to 96°C. The Chemex can handle hotter water due to its slower extraction.
Brew time too long (5:00+)? Your grind is too fine, or you've compacted the bed. Adjust coarser by 40-50 microns and pour more gently. Check that you rinsed the filter adequately—residual paper particles can clog.
Brew time too short (under 3:30)? Go finer by 30-40 microns to slow flow and increase extraction. You may also be pouring too aggressively, creating channels.
Papery taste? This isn't a grind issue—rinse your filter more thoroughly. The thick Chemex filter needs 200-300g of hot water to fully rinse.
Inconsistent extractions? Level your coffee bed before brewing and maintain consistent pour height and speed. With your grind dialed to a specific micron measurement, you can systematically adjust other variables—pour rate, water temperature, or coffee dose—knowing your particle size is constant.
Final Tips
Fresh beans matter. Coffee degases significantly after roasting—use beans within 2-4 weeks of roast date for best results. Store in an airtight container away from light and heat.
Water quality impacts flavor dramatically. Use filtered water with 50-150 ppm total dissolved solids for optimal extraction. The Chemex's clarity makes water quality particularly noticeable.
Keep a brewing journal. Note your micron setting, brew time, water temperature, and tasting notes for each coffee. The Chemex is sensitive to all variables, but recording exact micron measurements provides a reliable reference point when switching coffees or troubleshooting.
The Chemex rewards patience and precision. Its thick filter amplifies the impact of grind size adjustments—20-25 micron changes that might be subtle in other brewers become clearly noticeable here. Once you've mastered your grind size and gentle pouring technique, you'll consistently brew crystalline, exceptionally clean coffee that highlights the best qualities of your beans.
