Chemex
Chemex Bonded Filters Pre-Folded Squares Natural (FSU-100) - For 6, 8, 10-Cup Brewers
Natural, Unbleached Filters for Eco-Conscious Coffee Lovers
The Chemex FSU-100 Natural Pre-Folded Square Filter is the eco-friendly choice for Chemex brewing. These natural brown, unbleached filters feature the same convenient pointed corners as white FS-100 filters, but with minimal processing that retains the natural wood color.
Specifically designed for all standard Chemex sizes—6-cup, 8-cup, and 10-cup brewers—FSU-100 filters deliver the exact same laboratory-grade filtration as white filters, but with less manufacturing intervention. They're 20-30% thicker than standard coffee filters, removing undesirable oils, fats, bitterness, and sediment for crystal-clear, full-bodied Chemex coffee.
Key Features:
- 100 Filters Per Box - Long-lasting economical packaging
- Natural Unbleached Brown - Minimal processing, eco-friendly
- Pre-Folded Squares - Pointed corners for easy removal
- Fits 6, 8, 10-Cup Chemex - All standard sizes (NOT 3-cup)
- 20-30% Thicker - Superior filtration vs. regular filters
- No Oxygen-Cleansing - Only hot water baths, no whitening process
- Laboratory-Grade Paper - Removes oils, fats, bitterness, sediment
- Made in USA - Sustainably harvested North American materials
- Compostable & Biodegradable - Eco-friendly disposal
- Won't Burst or Break - Guaranteed durability during brewing
- Perfect Infusion Time - Engineered filtration rate
- Corner "Handles" - Easy to grab when hot
- Identical Performance to White - Same filtration, just brown
Compatible Chemex Models
Fits All Standard Chemex Brewers (6, 8, 10-Cup)
✓ COMPATIBLE WITH:
Classic Series (Wood Collar):
- CM-6A (6-Cup Classic - 30oz) - Most Popular
- CM-8A (8-Cup Classic - 30oz)
- CM-10A (10-Cup Classic - 50oz)
Glass Handle Series:
- CM-6GH (6-Cup Glass Handle - 30oz)
- CM-8GH (8-Cup Glass Handle - 40oz)
- CM-10GH (10-Cup Glass Handle - 50oz)
Handblown Series:
- CM-2 (Handblown 6-Cup)
- CM-3 (Handblown 8-Cup)
- CM-4 (Handblown 10-Cup)
Also Works With:
- Most cone-shaped pour-over brewers
- Other pour-over coffee makers requiring cone filters
✗ NOT COMPATIBLE WITH:
- CM-1C (3-Cup Classic Series) - Use FC-100 filters for 3-cup
- CM-1 (3-Cup Handblown Series) - Use FC-100 filters for 3-cup
- CM-1GH (3-Cup Glass Handle Series) - Use FC-100 filters for 3-cup
- CM-FNX (Funnex) - Use FP-2 half-moon filters for Funnex
Natural vs. White Filters: Which to Choose?
FSU-100 Natural Brown (This Product)
Processing: Natural filters go through hot water baths only, skipping the oxygen-cleansing step. This retains the natural brown wood color of the paper.
Benefits:
- ✓ Minimal processing - most natural option
- ✓ No oxygen-cleansing step
- ✓ Natural aesthetic appeals to eco-conscious users
- ✓ Same thickness and filtration as white filters
- ✓ No chemical residue (never had any to begin with)
- ✓ Identical brewing performance to white
Best For:
- Eco-minded coffee lovers
- Users who prefer natural, unbleached products
- Those who appreciate minimal processing
- Natural aesthetic preference
- Environmentally conscious households
FS-100 White (Alternative)
Processing: White filters undergo an oxygen-cleansing bath followed by hot water baths. This is a bleach-free process that whitens the paper without harsh chemicals.
Benefits:
- ✓ Bright white appearance
- ✓ Traditional filter aesthetic
- ✓ Same thickness and filtration as natural
- ✓ No chemical residue or taste
- ✓ Bleach-free oxygen cleansing
Best For:
- Users who prefer white filters
- Traditional aesthetic preference
- Those who want the whitened look
The Truth: They're Identical in Performance
Same Filtration Quality:
- Same 20-30% extra thickness
- Same bonded construction
- Same laboratory-grade paper
- Same coffee oils removed
- Same sediment filtration
- Same brew time
- Same taste in your cup
The ONLY Difference is Color FSU-100 (brown) and FS-100 (white) perform identically. The choice is 100% personal preference based on:
- Aesthetic preference (brown vs. white)
- Processing preference (minimal vs. oxygen-cleansed)
- Environmental philosophy
No taste difference. No quality difference. Just color.
Why Choose Natural Unbleached Filters?
The Eco-Conscious Choice
Minimal Processing Philosophy Every manufacturing step uses energy and resources. By skipping the oxygen-cleansing bath, natural filters have one less processing step—reducing environmental impact while maintaining identical performance.
Visual Transparency The natural brown color shows you exactly what you're getting—pure wood pulp with no additional processing. What you see is what you get.
Aesthetic Appeal Many coffee lovers prefer the natural, earthy appearance that aligns with the craft coffee movement and sustainable living philosophy.
Zero Compromise on Quality Natural doesn't mean lower quality. FSU-100 filters are the exact same thickness, use the same laboratory-grade bonded paper, and deliver the same pristine filtration as white filters.
Perfect Pairing Natural brown filters look stunning with the natural wood collar on Classic Chemex brewers—it's an aesthetic match made in heaven.
Why Square Filters Over Circles?
The Corner Advantage
Pointed Corners = Easy Removal The square shape creates four pointed corners that act as "handles" when removing the hot, wet filter after brewing. Simply grab a corner and lift—no fumbling, no burns.
Perfect Fit for All Standard Sizes FSU-100 square filters fit all 6, 8, and 10-cup Chemex models perfectly, with the points protruding slightly above the carafe rim for easy access.
Identical Performance to Circles Square and circle filters function identically—same thickness, same filtration, same quality. The choice is purely about removal preference.
Why Chemex Filters Are Superior
Laboratory-Grade Engineering Since 1941
Chemex filters aren't ordinary coffee filters—they're precision-engineered laboratory paper designed by chemist Dr. Peter Schlumbohm for one purpose: brewing perfect coffee.
The Science Behind the Filter:
20-30% Thicker Paper The extra thickness creates a denser filtration barrier that traps undesirable elements while allowing pure coffee flavor to pass through. This measurable difference is why Chemex coffee tastes so clean.
Bonded Construction Multiple layers are bonded together to create exceptional strength. The filter won't burst under the weight of water during brewing and won't break when you lift out the spent grounds—even by the corners.
Precise Filtration Rate The formulation regulates water flow—not too slow (over-extraction/bitterness), not too fast (under-extraction/weakness). The result is optimal infusion every time.
What Gets Filtered Out:
- ✓ Coffee oils (cafestol and kahweol) - reduces bitterness and acidity
- ✓ Fine sediment particles - creates clean, clear coffee
- ✓ Undesirable fats - eliminates oily mouthfeel
- ✓ Bitter compounds - allows stronger brewing without bitterness
What Passes Through:
- ✓ Desirable flavor compounds
- ✓ Natural sweetness
- ✓ Aromatic oils (in appropriate amounts)
- ✓ Full-bodied richness
Product Specifications
Package Details:
- Quantity: 100 filters per box
- Model Number: FSU-100
- Filter Type: Pre-folded squares, natural (unbleached)
- Shape: Cone (when opened) with square corners
- Color: Natural brown
Filter Specifications:
- Material: Bonded laboratory-grade filter paper
- Thickness: 20-30% thicker than standard coffee filters
- Color: Natural brown (unbleached wood pulp)
- Construction: Multi-layer bonded
- Corner Design: Pointed for easy removal
- Processing: Hot water baths only (no oxygen-cleansing)
Manufacturing:
- Made in: United States
- Materials: 100% North American materials
- Sustainability: SFI, FSC, and PEFC certified
- Processing: Hot water baths (no bleaching or oxygen-cleansing)
- Cut: Each filter individually cut at Chemex factory in Massachusetts
Environmental:
- Compostable: Yes
- Biodegradable: Yes
- Recyclable: Yes (as paper product)
- Chemical-free: No bleach, no oxygen-cleansing, no harsh chemicals
- Minimal Processing: Least processed Chemex filter option
How to Use Chemex FSU-100 Filters
Step-by-Step Brewing Instructions
Step 1: Prepare the Filter
- Remove one pre-folded natural square filter from the box
- The filter is already creased into quarters
- Gently open the filter with your fingers
- Separate the layers so 3 leaves are on one side, 1 leaf on the other
Step 2: Position in Chemex
- Place the filter in the top of your Chemex brewer
- Position the 3-layer side against the spout/groove
- The four square corners will protrude slightly above the rim
- The natural brown color pairs beautifully with wood collar Chemex
Step 3: Rinse the Filter (Recommended)
- Pour hot water through the empty filter
- This removes any paper taste and preheats the Chemex
- With natural filters, rinsing is especially recommended
- Discard rinse water through the spout
Step 4: Add Coffee
- Use 1 heaping tablespoon (about 7-8g) per cup
- For 6-cup Chemex (30oz): 42-48g coffee (6-7 tablespoons)
- For 8-cup Chemex (40oz): 56-64g coffee (8-9 tablespoons)
- For 10-cup Chemex (50oz): 70-80g coffee (10-11 tablespoons)
- Adjust to taste after first brew
Step 5: Brew Your Coffee
- Follow standard Chemex brewing method
- Bloom: Pour twice the weight of coffee in water, wait 30-45 seconds
- Pour in circular motion to ensure even saturation
- Total brew time: 3.5-4.5 minutes
Step 6: Remove & Discard
- Grab a corner of the natural square filter
- Lift out grounds and filter together
- Natural filter is just as strong as white
- Compost the filter and grounds together
Brewing Tips for Best Results
Getting the Most from Your FSU-100 Filters
Always Rinse Natural Filters While rinsing is recommended for all Chemex filters, it's especially important with natural brown filters. The hot water rinse removes any minimal wood taste and ensures the purest cup.
Water Temperature
- Ideal: 195-205°F (90-96°C)
- Boil water, then wait 30-60 seconds before pouring
Coffee-to-Water Ratio
- Standard: 1:15 to 1:17 (coffee to water)
6-cup (30oz): 42-48g coffee
8-cup (40oz): 56-64g coffee
10-cup (50oz): 70-80g coffee - Stronger: 1:13 to 1:14
- Lighter: 1:17 to 1:18
Grind Size
- Medium-coarse (similar to sea salt)
- Not too fine (causes over-extraction)
- Not too coarse (causes under-extraction)
Pour Technique
- Start in center, spiral outward
- Avoid pouring directly on filter walls
- Keep grounds evenly saturated
- Pour slowly and steadily
Brew Time
- Total: 3.5-4.5 minutes
- Faster = under-extracted (weak, sour)
- Slower = over-extracted (bitter, harsh)
- Adjust grind size to control brew time
Filter Positioning
- Always place 3 layers against spout
- This prevents vacuum lock
- Ensures proper airflow during brewing
- Provides structural support
- Natural brown corners should protrude for easy removal
Frequently asked question
Choose 3-cup if: You typically brew for yourself, have limited counter space, or want a travel/office brewer. Makes 1-2 standard mugs.
Choose 6-cup if: You brew for 2 people, want the most versatile option, or like having multiple cups throughout the morning. Makes 2-4 standard mugs. This is the most popular size.
Choose 8-cup if: You have a family of 3-4, entertain regularly, or want to brew larger batches. Makes 3-5 standard mugs.
Choose 10-cup if: You have a large family, brew for an office, host frequent gatherings, or want maximum capacity. Makes 4-6 standard mugs.
Remember: Chemex measures in 5 oz cups, while most coffee mugs hold 8-12 oz.
- 3-cup Chemex: Makes 1-2 standard mugs (15-17 oz total)
- 6-cup Chemex: Makes 2-4 standard mugs (30 oz total)
- 8-cup Chemex: Makes 3-5 standard mugs (40 oz total)
- 10-cup Chemex: Makes 4-6 standard mugs (50 oz total)
3-cup Chemex: Requires square Chemex bonded filters (available in natural or bleached)
6, 8, and 10-cup Chemex: All use the same circle Chemex bonded filters (available in natural or bleached)
You cannot use regular coffee filters—only genuine Chemex bonded filters will work properly.
Bleached (White) Filters:
- Oxygen-bleached (not chlorine), environmentally safe
- No paper taste
- Preferred by most coffee professionals
- Slightly easier to use
Natural (Unbleached) Filters:
- Less processing
- May impart slight paper taste if not rinsed well
- Preferred by eco-conscious users
- Require thorough rinsing
Both produce excellent coffee. It's a matter of personal preference.
No, Chemex filters are sold separately. We recommend ordering filters at the same time as your Chemex so you can start brewing immediately. Subscribe & Save for automatic filter delivery and discount pricing.
No. Regular coffee filters are too thin and will not properly filter the coffee or maintain the structural integrity needed for the Chemex brewing process. Only genuine Chemex Bonded Filters are designed to work with Chemex brewers.
Yes! The polished wood collar is designed to be removable. Take it off before putting your Chemex in the dishwasher or for thorough hand washing. This extends the life of both the glass and the wood.
Yes, the glass carafe is dishwasher safe. However, always remove the wood collar and leather tie before washing. We recommend hand washing to preserve the beauty of your Chemex for generations.
Chemex produces cleaner, brighter coffee because the thick bonded filters remove more oils and fine particles than standard drip machine filters. The pour over method also gives you complete control over water temperature, saturation, and brew time—variables that automatic drip machines can't match. The result is a more nuanced, complex cup that highlights your coffee's unique characteristics.
With proper care, your Chemex can last a lifetime. The borosilicate glass is extremely durable and heat-resistant. Many Chemex owners have used the same brewer for 20, 30, or even 40+ years. The wood collar and leather tie can be replaced if needed, but the glass carafe is built to last generations.
The Classic Series features the iconic polished wood collar and leather tie—this is the original design from 1941.
Other Chemex models include:
- Glass Handle Chemex: All-glass design without wood collar
- Chemex Ottomatic: Automatic pour over brewer
The Classic Series is the most recognized design and what most people picture when they think of Chemex.
Use a medium-coarse grind, similar to the texture of sea salt.
- Too fine = over-extracted, bitter coffee and slow brew time
- Too coarse = under-extracted, weak coffee and fast brew time
- Just right = balanced extraction in 3.5-4.5 minutes
A quality burr grinder is highly recommended for consistent results.