Key takeaways
- Paper filters dictate flow rate, which influences coffee extraction, flavour, and mouthfeel.
- Filters now vary in density, thickness, structure, and permeability level.
- Advanced filters enable targeted extraction and experimentation across roast profiles and processing methods.
- Choosing different filters can improve clarity, sweetness, and body.
Paper coffee filters have moved far beyond their basic function. Once a simple barrier between coffee grounds and water, they now have a huge impact on the brewing process.
“Advanced paper filters have become one of the most influential physical variables in manual brewing,” says Lakis Psomas, a Swedish Barista & Brewers Cup Champion and the Marketing and Innovation Manager at Beans in Cup.
“We now have access to papers with different densities, fibre structures, permeability levels, and even hydrophobic properties. This gives brewers a much wider creative palette to work with.”
Brands like Sibarist, Cafec, and Kinto now produce filters with specific properties, which give baristas unprecedented control over flow rate, influencing flavour and mouthfeel.
You may also likeour article on whether you should use different paper filters for different roast profiles.
How paper filters help control flow rate
There are myriad brewing variables to consider in specialty coffee. Flow rate – the speed at which water is introduced into or moves through coffee grounds – has become an increasingly important one in recent years.
For pour over, flow rate describes how quickly the barista pours water onto the coffee bed. Pour too slowly, and the coffee will overextract. Pouring too quickly, meanwhile, will result in sour, underextracted flavours with a thin mouthfeel.
Slowing down or speeding up your pour directly controls the flow rate to achieve optimal extraction. Tools like the Melodrip and Hario’s Drip Assist can help regulate flow rate, but more advanced paper filters play a key role as well.
“A filter influences how quickly water moves through the coffee and how oils, sugars, and acids pass into the final cup,” Lakis explains. “All of this directly affects mouthfeel and flavour balance.”
As baristas have become more knowledgeable about how paper filters affect flow rate, manufacturers have responded by offering a wider range of options. Cafec, for example, offers different filters based on roast profile that result in different flow rates, including:
- T-92/TH-1: high density, 0.15mm thickness, and one-sided crepe for a slower flow rate.
- T-90/TH-3: low density, 0.28mm thickness, and two-sided crepe for a medium-fast flow rate.
- T-83/TH-2: medium density, 0.22mm thickness, and two-sided lower crepe for a faster slow rate.
“The impact of paper filters can be significant,” says Joaquim Morató Pujol, the co-founder of Sibarist, which manufactures a range of paper filters. “A poorly chosen filter can flatten or dull the flavour of a 90+ point coffee, while the right filter can make a ‘regular’ coffee truly shine.”
Advanced filters are fuelling experimentation in coffee brewing
The choice between paper filters was once simply bleached vs. unbleached. But now, they have become a brewing variable in their own right. With advances in brewing equipment and greater diversity in coffee processing and roast profiles, the material and thickness of paper filters matter more than ever.
“Flavour compounds in coffee dissolve at different rates: some extract very quickly with hot water, while others require more contact time,” Joaquim explains. “Based on this principle, each Sibarist filter has a specific level of permeability that favours the extraction of a particular combination of soluble compounds.
“This directly shapes the final flavour profile and mouthfeel in the cup,” he adds. “The FAST filter speeds up flow rate to increase extraction in less time. It enhances early-extracting compounds, which accentuate acidity, complexity, and vibrancy.”
“The B3 filter is a medium-fast flow filter that allows for slightly more coffee development. It balances acidity while emphasising sweetness and structure, producing a more syrupy, rounded cup with heavier mouthfeel, longer aftertaste, and more depth.”
Paper and beyond
Hydrophobic properties are one of the latest innovations in coffee filters. Although not made of paper, but rather a blend of polypropylene (PP) and polyethylene (PE), Perme are designed to behave like traditional paper filters, but with a key difference.
“The Perme allows for two distinct brewing approaches. The first is a traditional method, where you add coffee first, and brewing begins as normal,” explains Julijan Markovic, the founder of Brew Methods and the creator of Perme filters. “This generally produces a richer cup with slightly higher extraction, largely due to increased agitation during the initial pour.
“The second approach is an inverse bloom, where water is added before the coffee,” he adds.
Lakis used another brand of hydrophobic filters at the 2025 World Brewers Cup and opted for the inverse bloom. “I used a very unique pouring structure,” he explains. “I started with water first and then added the coffee, and stirred the bloom. Working with a very high-quality coffee, this allowed me to push extraction much further without creating undesirable flavours.”
“The Perme’s PP and PE blend is non-polar, whereas water is polar. Polar and non-polar substances don’t mix,” says Julijan. “Oil, however, is non-polar, allowing it to penetrate the surface tension of the filter and activate its permeability. Once activated, the filter allows polar compounds, like water, to pass through.
“Because it takes a few seconds for the oils in coffee to penetrate the filter, flow is intentionally restricted in the early stages,” he adds. “As brewing progresses and more oils interact with the filter, flow rate increases toward the end of the brew.”
Practical tips for using different paper filters
The simplest way to choose between filter papers is to consider the flavour profile of the coffee you’re using.
“For delicate, floral, or high-acid coffees, I prefer faster-flow filters,” Lakis tells me. “They preserve clarity, aromatics, and a lighter mouthfeel, making the coffee feel more elegant and cleaner.
“For heavier, sweeter, or more processed coffees, a slightly denser filter can help build sweetness and texture through longer contact time.”
The type of brewing method is another key consideration. “With immersion or hybrid brewers, where water and coffee already have long contact, I often use faster filters to avoid over-extraction and keep the cup clean and lively,” Lakis adds.
Additionally, processing method can influence which type of filter to use. “Washed coffees typically contain less surface oil, as most of the oils remain locked within the bean’s cellular structure,” Julijan explains. “As a result, washed coffees take longer to permeate the filter.
“Natural processed coffees are dried with the cherry intact, which generally results in higher oil availability on the surface of the bean. As a result, they activate the filter’s permeability more quickly,” he adds. “Heavily processed coffees, such as natural anaerobics or thermal shock processed coffees, tend to activate the filter even faster due to their higher and more accessible oil content.”
More professional and home baristas are recognising the importance of filters in the brewing process. In turn, there’s room for further experimentation to unlock new flavours.
“Don’t treat filters as an afterthought,” Lakis concludes. “Try the same coffee with two different papers, and you will immediately feel how mouthfeel, clarity, and balance can change.”
Enjoyed this? Then readour article on choosing the best paper filter for your coffee.
Photo credits: Sibarist, Brew Methods
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