Amongst the variety of machines and methods for making filtered coffee, there is also a vast range of models, sizes, and options of paper filters. Apart from specifications regarding formats (flat bottom or conical strainers, for Chemex or Aeropress, or more), there is also the criterion regarding color and chemical processing.
Why are there paper coffee filters that are white in color and others that are brown in color?
In the midst of so many variables to understand regarding the brew of a pour-over, this question may seem simple, yes…however, the color of paper filters influences much more than one can imagine, from porosity and percolation index to health-related issues.
Read on to learn more about the difference between bleached and unbleached coffee filters, the raw materials they are made of, and why different production processes can alter the quality of the coffee brewed.
In This Guide:
- Paper filters for coffee brewing: how they are made
- Why are paper coffee filters bleached white?
- Are brown paper coffee filters inferior to white paper filters?
- Coffee-Paper filters: the natural raw materials explained
- White-bleaching coffee filter methods and health hazards
- The sustainability and environmental impact of paper coffee filters
- Pairing bleached and unbleached coffee papers to grind and roast levels
Paper filters for coffee brewing: how they are made
In 1908, German housewife Melitta Bentz sought a way to brew coffee without the bitter taste and sediment that often came with cloth filters. She experimented with different materials, including blotting paper from her son’s school notebook. Melitta eventually punched holes in a brass pot. She lined it with paper to create the first coffee filter that allowed her to brew a smooth cup of coffee. Melitta then began selling the paper filters she had invented, thus making the Melitta company.
Filter papers for the coffee industry can be created entirely from plant-based materials or by blending various sources, such as natural, synthetic, or even glass fibers. The sources for raw materials can include mineral fiber pulps, fiber crops, softwoods, and hardwoods.
The length of the fibers used in any filter paper production process can determine the porosity of the paper, which, when it comes to coffee-paper filters, can significantly affect the level of extracted compounds and oils in the final beverage.
High quality, specialty coffee experts-approved paper coffee filters can be made from various types of natural-raw materials: wood pulp, hemp pulp (abaca), cotton pulp, and other natural fibers.
Some coffee filters may contain a small amount of plastic, such as polypropylene, which helps to hold the filter together and prevent it from tearing during use – the amount of plastic is typically minimal and considered safe for consumption. Plastic-free coffee paper filters contain packaging labels that say “made only from natural materials.”
Every single paper coffee filter is naturally brown in color – all of them. Paper that is not brown or in shades of brown has undergone a chemical bleaching process.
Why are paper coffee filters bleached white?
Bleached coffee filters are also made from chemically treated wood pulp or other natural fibers. Many confuse the term “bleached” with “not plant-based” sourced, which is equivocated. Paper coffee filters can be 100% naturally sourced but bleached, 100% naturally sourced and unbleached, or bleached and hybrid sourced (synthetic + natural).
There are a few motives on why paper coffee filters are bleached. One of the reasons is marketing: coffee paper filters became white to “smooth” the natural texture of vegetal-based papers, which are naturally grainy, as well as to create a white, uniform appearance.
But the main reason for the bleaching processing on paper coffee filters is to rid any unwanted impurities that may cause the filter to break down more quickly and affect the beverage’s taste and aroma by bringing in unwanted flavors or odors.
Those impurities include residual lignin, hemicellulose, extractives, ash, and other leftover chemicals. Bleaching coffee filters used to be the most trustworthy processing method to engender a cleaner, more consistent flavor in the coffee.
But nowadays, the offerings in the market have expanded to include 100% naturally sourced and unbleached options that achieve excellent results as well.
Are brown paper coffee filters inferior to white paper filters?
With time, the manufacturing methods of paper coffee filters evolved. Now there are also many top quality unbleached options (the natural, brown-ish paper coffee filters) on the market that do not compromise taste and flavor. On the contrary, there are professional brewers who believe that their texture enhances cup profiles.
The choice of raw material can depend on factors such as strength, porosity, filtration capabilities, and sustainability. Unbleached coffee filter papers may have some natural color variation, mainly in shades of brown, due to using raw materials and lacking bleaching agents.
Additionally, sustainability and eco-friendliness are becoming increasingly important holistically in the coffee industry, which includes certification for naturally sourced coffee-paper filters.
The best-reviewed brands of the specialty coffee segment produce biodegradable and FSC-certified papers (Forest Stewardship Council) made of 100% virgin material from FSC-certified forests, regardless of whether the filters are bleached.
Other types of seals to look for in coffee filters are those of the Sustainable Forestry Initiative (SFI) and the Programme for the Endorsement of Forest Certification (PEFC).
Coffee-Paper filters: the natural raw materials explained
Bamboo and abaca have the longest fibers among the raw materials used in coffee filter paper manufacturing. These two are the most porous vegetal materials used in coffee-paper filter production, which accounts for more oils and compounds from the coffee grounds that can enter the cup. While this can contribute to a richer, more flavorful brew, it results in more coffee grounds passing through to the beverage.
Another commonly used raw material is Eucalyptus pulp, which has shorter fibers than Bamboo and Abaca. Consequently, Eucalyptus-based paper filters have the smaller porous of all the pulps. Therefore, the coffee extracted tends to have a cleaner, smoother cup consistency since fewer oils and compounds are present in the brew.
For example, the American coffee machine and accessories company CHEMEX and the Japanese Hario produce both white and brown natural-sourced coffee-filter papers.
There is no difference in the manner in which brewers should prep their filters, bleached or not: “it is always recommended to pre-wet or rinse the papers prior to use to ensure that no paper taste is transferred during the brewing process”, says the Hario V60 filter papers FAC sheet.
White-bleaching coffee filter methods and health hazards
Bleached coffee paper filters: not all are the same.
There are different methods of bleaching paper filters; the most commonly used ones are chlorine or oxygen-based bleaching, the last being considered the “purest” one. Some people may be allergic or sensitive to certain materials used in white coffee filters, such as chlorine or other chemicals.
Chlorine-based bleaching involves using chlorine gas or bleach to remove impurities and whiten the paper. However, this method has been associated with releasing harmful chemicals into the environment. The chlorine-dioxide bleaching method is called ECF.
The tendency in this market is that manufacturers have switched to oxygen-based bleaching methods as a more environmentally friendly and health-conscious alternative.
Oxygen-based bleaching involves using hydrogen peroxide or ozone as the primary chemical agent to whiten the papers, which is a technique called TFC. This method is generally considered safer and more environmentally friendly than chlorine-based bleaching.
Oxygen-based bleaching may not achieve the same brightness level as chlorine-based bleaching.
The sustainability and environmental impact of paper coffee filters
Using 100% natural fiber filters can help reduce the environmental impact of coffee production. According to researchers, the bleached versus unbleached coffee-paper filter debate is also a matter of sustainability.
A study published in the Journal of Cleaner Production found that using unbleached coffee filters can significantly reduce the amount of waste generated by coffee consumption compared to using bleached filters. This is because unbleached filters can be composted or recycled more efficiently than bleached ones, which may contain harmful chemicals.
Even though both types of unbleached and bleached filter papers are passable for decomposing, unbleached coffee-filter papers must be torn into smaller pieces for faster disintegration.
For eco-friendly, recyclable bleached paper coffee filters, coffee brewers must look for entirely plant-based brands that employ chlorine-free, oxygen-bleaching techniques (the before-mentioned TFC pulps).
High-quality coffee filters manufacturers that produce 100% naturally sourced and bleached products are Hario, Melitta, Koar, Aeropress and Moccamaster.
Pairing bleached and unbleached coffee papers to grind and roast levels
Experienced baristas generally prefer unbleached paper filters due to their more tightly-knit fibers, which provide more clarity in the cup. However, as explained before, denser papers are harder to use and can lead to over-extraction or bitterness.
Loose-knit paper filters are easier to use but result in less clarity and vibrancy in the cup. On the other hand, abaca-based papers for advanced brewers may solve problems such as cellular-residual and poor resistance during extraction.
Thicker coffee filters should be used with coarse-grinded coffees and lighter roasts to slow down the water flow, aiming to achieve less body but more pleasant acidity in the brew.
Thinner filters are ideal for darker roasts and finely ground coffees, which are easier to extract and result in a faster brew time.
Ultimately, the best method is the one that produces the best result for each particular brewer. This, of course, requires testing the combination of variables such as bleached and unbleached with papers made from different raw materials and varied grinding and roasting levels.
Fundamentally, the choice between brown and white coffee filters comes down to personal preference, unique tastes or specific demands, and sustainability and health values.
And in terms of green living, durability, and environmental impact overall, using brown coffee filters made from natural fibers is proven to be a better choice for consumers looking to align with these values.
Isabelle Mani SanMax is a writer and digital content specialist with expertise in coffee-market-related topics. She has also contributed to PerfectDailyGrind. Loves coffee negronis and coffee festivals.