Chemex Bonded Filters Pre-Folded Squares (FS-100) - For 6, 8, 10-Cup Brewers

The Most Popular Chemex Filter - Perfect for 6, 8, and 10-Cup Brewers

The Chemex FS-100 Pre-Folded Square Filter is the gold standard for Chemex brewing. These white, oxygen-cleansed filters feature convenient pointed corners for easy removal and are specifically designed to fit all standard Chemex sizes—6-cup, 8-cup, and 10-cup brewers.

Based on laboratory-grade filter paper engineered by chemists, FS-100 filters are 20-30% thicker than standard coffee filters, removing undesirable oils, fats, bitterness, and even the finest sediment particles. The result? Crystal-clear, full-bodied coffee with zero bitterness—the signature Chemex taste.

Key Features:

• 100 Filters Per Box - Long-lasting economical packaging
• 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
• Oxygen-Cleansed White - Bleach-free, no chemical taste
• 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
• Also Fits Other Brewers - Works with most cone-shaped pour-overs

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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 - 40oz)
• 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

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Why Choose 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 FS-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.

When to Choose Squares (FS-100):

• You prefer easy corner-grab removal
• You want convenient "handles" after brewing
• You like the pointed aesthetic
• You brew for multiple people regularly

When to Choose Circles (FC-100 for 3-cup):

• You have a 3-cup Chemex (squares don't fit 3-cup)
• You prefer flush top edge with no corners
• You like minimalist, streamlined appearance

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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

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White vs. Natural Filters

Oxygen-Cleansed White Filters (This Product: FS-100)

Oxygen-Cleansing Process: White Chemex filters undergo an oxygen-cleansing bath followed by hot water baths. This is a bleach-free process that whitens the paper without using chlorine or harsh chemicals.

Benefits:

• Absolutely no chemical residue or taste
• Bright white appearance
• Some users prefer traditional white aesthetic
• Identical performance to natural filters

Best For: Users who prefer white filters or want the cleanest visual appearance

Natural Brown Filters (Alternative: FSU-100)

Natural Processing: Natural filters skip the oxygen-cleansing step and go through only hot water baths, retaining the natural brown wood color.

Benefits:

• Minimal processing
• Natural, eco-aesthetic
• Less manufacturing intervention
• Identical performance to white filters

Best For: Users who prefer unbleached appearance or minimal processing

The Bottom Line: Both FS-100 (white) and FSU-100 (natural) square filters function identically. The choice is purely personal preference—there's no difference in taste, brewing performance, or quality.

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Product Specifications

Package Details:

• Quantity: 100 filters per box
• Model Number: FS-100
• Filter Type: Pre-folded squares, white (oxygen-cleansed)
• Shape: Cone (when opened) with square corners

Filter Specifications:

• Material: Bonded laboratory-grade filter paper
• Thickness: 20-30% thicker than standard coffee filters
• Color: White (oxygen-cleansed)
• Construction: Multi-layer bonded
• Corner Design: Pointed for easy removal

Manufacturing:

• Made in: United States
• Materials: 100% North American materials
• Sustainability: SFI, FSC, and PEFC certified
• Processing: Oxygen-cleansed (bleach-free)
• Cut: Each filter individually cut at Chemex factory in Massachusetts

Environmental:

• Compostable: Yes
• Biodegradable: Yes
• Recyclable: Yes (as paper product)
• Chemical-free: No bleach or harsh chemicals used

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How to Use Chemex FS-100 Filters

Step-by-Step Brewing Instructions

Step 1: Prepare the Filter

• Remove one pre-folded 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 groove is the air vent and pouring spout
• The thicker 3-layer side prevents vacuum-sealing and provides stability

Step 3: Rinse the Filter (Recommended)

• Pour hot water through the empty filter
• This removes any paper taste and preheats the Chemex
• 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 square filter (this is why squares are great!)
• Lift out grounds and filter together
• Filter won't break even when lifting by corner
• Compost the filter and grounds

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Brewing Tips for Best Results

Getting the Most from Your FS-100 Filters

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
• Corners should protrude for easy removal