The filter is arguably the most important variable in Chemex brewing. Chemex Bonded filters are based on laboratory-grade paper, developed by the same chemist, Dr. Peter Schlumbohm, who designed the Chemex brewer itself back in 1941. That scientific heritage matters: these filters are 20-30% thicker than standard paper coffee filters, which gives them the density to trap unwanted oils, fats, bitterness, and fine sediment while still allowing the full, clean flavour of your coffee to come through at the right pace. The result is that distinctively bright, clear cup that has made the Chemex method a fixture in specialty coffee for over 80 years.
We stock two filter types to cover the Chemex range. The FS-100 is a pre-folded white square filter designed for 6, 8, and 10-cup Chemex brewers. The square shape creates four pointed corners that sit just above the rim of the carafe, making it easy to remove the spent filter after brewing without burning your fingers. The FP-2 is the halfmoon filter for the 3-cup Chemex and Funnex models; these are not pre-folded and require a simple fold before use. Both are made from the same oxygen-cleansed, bonded paper and perform identically in terms of filtration quality. As with any paper filter, a quick rinse with hot water before brewing is always worth doing to remove any residual paper taste and bring the glass up to temperature.
All Chemex filters are manufactured in the USA using only North American materials, and the paper is sourced in line with SFI, FSC, and PEFC sustainable forestry programmes. They're fully compostable too, so the used filter and your spent grounds can go straight on the compost heap together. These are the only filters we'd recommend for use with a Chemex coffee maker; the thickness and bonded construction are specific to the Chemex method, and thinner generic filters simply won't perform in the same way. For everything you need to know about grind size, water temperature, and pour technique, take a look at our Chemex brew guide.
- Brand: Chemex (USA)
- Filter type: Bonded paper filter
- Paper thickness: 20-30% thicker than standard coffee filters
- Paper type: Laboratory-grade bonded paper
- Bleaching: Oxygen-cleansed, bleach-free process (white filters only)
- Colour: White
- Country of manufacture: USA (North American materials only)
- Certifications: SFI, FSC, and PEFC certified sustainable forestry
- Compostable: Yes, fully compostable
- FS-100 (6 cup)
- Shape: Pre-folded square
- Compatible brewers: All 6, 8, and 10-cup Chemex models (CM-6A, CM-8A, CM-10A, CM-6GH, CM-8GH, CM-10GH, CM-2, CM-3, CM-4)
- Not compatible with: 3-cup Classic, 3-cup Handblown, 3-cup Glass Handle Series, and Funnex
- Pack size: 100 filters
- Product code: FS-100
- FP-2 (3 cup)
- Shape: Halfmoon (requires folding before use)
- Compatible brewers: 3-cup Chemex Classic Series (CM-1C), 3-cup Handblown (CM-1), 3-cup Glass Handle (CM-1GH), and Funnex (CM-FNX)
- Pack size: 100 filters
- Product code: FP-2
What is the difference between the FS-100 and FP-2 Chemex filters? They are designed for different Chemex brewers. The FS-100 is a pre-folded white square filter for 6, 8, and 10-cup Chemex models. The FP-2 is a halfmoon-shaped filter for the 3-cup Chemex and Funnex brewers. Both are made from the same laboratory-grade bonded paper and deliver the same filtration performance; the difference is purely in shape and size to match the respective brewers.
How do I fold the FP-2 halfmoon filter? The FP-2 is not pre-folded, so it requires a simple fold before use. Fold the halfmoon in half to create a cone shape, then open the cone so that three layers of paper are on one side. Place the three-layer side against the spout of the Chemex when inserting the filter. This ensures stability during brewing and prevents the filter from vacuum-sealing against the glass.
Do I need to rinse Chemex filter papers before use? Yes, it's a good habit. Rinsing the filter with hot water before adding your coffee grounds removes any residual paper flavour and pre-heats the glass carafe at the same time. Remember to discard the rinse water before you start brewing.
Why are Chemex filters thicker than regular coffee filters? Chemex Bonded filters are based on laboratory-grade paper and are 20-30% thicker than standard coffee filters. This extra density allows them to trap undesirable oils, fats, bitterness, and fine sediment that thinner filters leave behind, producing the clean, bright cup that Chemex brewing is known for.
Are Chemex filter papers compatible with other brewers? The FS-100 square filters are cone-shaped once opened and can technically fit other cone-style brewers. However, they are specifically designed and optimised for the Chemex. The FP-2 halfmoon filter is exclusively for the 3-cup Chemex and Funnex models.
Are Chemex filter papers compostable? Yes. Both the FS-100 and FP-2 filters are fully compostable. You can add the used filter along with your spent coffee grounds directly to a compost bin.
Are Chemex filters sustainably sourced? Yes. Chemex filter paper is manufactured in the USA using only North American materials, and production adheres to SFI (Sustainable Forestry Initiative), FSC (Forest Stewardship Council), and PEFC sustainable forestry programmes.
Can I use regular coffee filters in my Chemex? We wouldn't recommend it. Chemex brewers are designed to work specifically with Chemex Bonded filters. Standard filters are significantly thinner and won't provide the same level of filtration, flow rate control, or structural strength. Using a thinner filter risks it collapsing or bursting during brewing, and the cup quality will be noticeably different.
How do I open and insert the FS-100 square filter? Open the pre-folded filter into a cone shape using your finger, ensuring three layers of paper are on one side. Place the three-layer side against the spout of the Chemex before adding your coffee grounds. This adds stability and helps prevent the filter from being pulled against the glass by suction during brewing.
How many filters come in a pack? Both the FS-100 (6 cup) and FP-2 (3 cup) are sold in packs of 100 filters.
The Story Behind Chemex
The Chemex was invented in 1941 by Dr. Peter Schlumbohm, a German chemist with a passion for elegant design and scientific precision. Drawing on his laboratory background, Schlumbohm set out to create the perfect brewing vessel: one that was simple to use, beautiful to look at, and capable of producing an exceptionally clean cup of coffee. The result was the Chemex Coffeemaker, a single piece of non-porous borosilicate glass with an hourglass silhouette and a polished wood collar, virtually unchanged to this day.
Schlumbohm's masterstroke was the filter. Rather than adapting existing filter papers, he developed a bonded laboratory-grade paper specifically for the Chemex, 20-30% thicker than standard filters, designed to remove oils, bitterness, and sediment while letting the true character of the coffee shine through.
The Chemex went on to be recognised as one of the finest examples of modern design, earning a permanent place in the collection of the Museum of Modern Art in New York. More than 80 years on, it remains a staple of specialty coffee culture worldwide, beloved for producing a cup that is bright, clean, and deeply satisfying. At Ozone, it's one of our favourite ways to brew.