The Difference Between Coffee Filters Is Bigger Than You Think! Which is Better: Bleached or Unbleached Coffee Filters? What Are the Best Coffee Filter Brands?

Understanding the Impact of Filter Paper on Coffee Extraction

As we all know, filter paper is an essential filtering tool because it single-handedly shoulders the "important task" of separating coffee grounds. However, precisely because this responsibility is so significant, most people's focus on it remains solely on filtration.

But in reality, filter paper, just like filter cups, comes in different styles and materials. These differences directly affect brewing, which in turn influences coffee extraction and flavor. Today, FrontStreet Coffee will share how the differences between filter papers manifest, and how these differences impact brewing and coffee flavor.

1. Filter Paper Materials

Since wood pulp filter papers are the most common and frequently used on the market, many people believe that the only differences between filter papers lie in size, model, and whether they're bleached. However, besides the common wood pulp filter papers we're familiar with, there are also filter papers made from non-woven fabric, hemp, plastic, and other materials.

These material differences primarily affect filtration performance! Take wood pulp and non-woven filter papers as examples: wood pulp filter papers have extremely high filtration performance, making it difficult for substances other than liquids to pass through; while filter papers made from non-woven fabric (or should we call them filter cloths?) have relatively lower filtration performance, so besides coffee liquid, coffee oils or extremely fine particles can also pass through. (Left side shows non-woven filter paper)

Due to this difference, the final coffee expression will vary. Because wood pulp filter papers have high filtration performance and don't allow substances other than coffee liquid to pass through, the resulting coffee will have extremely high clarity; while non-woven filter papers allow oils and extremely fine particles to pass through, so although the resulting coffee may not be as clear, it will have a richer, fuller mouthfeel when consumed.

2. Filter Paper Manufacturing Process

Even filter papers made from the same material can have significant differences due to different manufacturing processes. These differences mainly manifest in the filter paper's construction, such as the use of textured creases or thickness levels. The two filter papers in the image below are both made from virgin wood pulp, but their manufacturing processes differ, so we can directly observe their differences from the surface.

Manufacturing process differences exist not only between different manufacturers but even within the same company using different processes to produce filter papers. The reason is simple: filter paper structure affects water flow speed, and water flow speed is an important factor in coffee extraction, so many manufacturers develop filter papers with different structures based on different brewing characteristics! Taking Japan's Sanyo Sangyo as an example, they designed three versions of filter papers specifically for different coffee bean roast levels: T-83, T-90, and T-92, corresponding to dark, medium, and light roast beans (the model numbers correspond to the appropriate water temperature). You can see the specific differences directly in the image~

As you can see, although the filter paper materials are the same, their water permeability speeds differ due to structural variations. And it's not just Sanyo Sangyo—other filter paper manufacturers have made similar approaches. FrontStreet Coffee is just using this as an example and won't go into further detail here~

3. Bleached vs. Unbleached

Finally, another difference in manufacturing process, but compared to the previous one, this topic receives more attention. Since wood pulp filter papers are the most widely used, and this type of filter paper is mainly divided into bleached and unbleached varieties, the difference between these two has always been a topic of intense discussion: which is better to use, bleached or unbleached filter paper!

The advantage of unbleached filter paper is that it hasn't undergone bleaching, so while it may have a distinct woody taste, at least it's healthier for the human body—this was previously a reason why unbleached filter paper was considered superior to bleached filter paper. However, with technological advancement, most brands today use enzyme bleaching processes, and this type of bleaching doesn't have significant impact on human health. Additionally, since unbleached filter paper has a more obvious woody taste that can affect coffee, most people choose to use bleached filter paper. However, nowadays some major brands' unbleached filter papers no longer have such strong woody tastes due to technological progress. Moreover, the slight woody taste of unbleached filter paper can, to some extent, add layers to the coffee's complexity—if you don't want it, simply rinse it with hot water and it will disappear. Therefore, neither is inherently better—the specific choice depends on our intended use. (That said, FrontStreet Coffee still prefers bleached filter papers~)

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